Diseases of the Horse's Foot
by
Harry Caulton Reeks
Part 3 out of 8
At the same time, its structure becomes more compact, the cribriform
appearance of its anterior and lateral faces more or less destroyed, and
the few remaining openings apparently increased in size. This atrophy of
the os pedis is best noted at the wings.
In the plantar cushion the effects of the atrophy are noted in the
smallness of the organ, in its becoming whiter in colour than normal, and
more resistant to pressure.
The coronary cushion is also affected in the same way, where the changes
are noted most in its posterior portions.
A further effect of the narrowing of the heels, and their consequent
tendency to drop downwards, is the exertion of a continual pressure on the
sensitive sole. In course of time, and especially in flat feet, this leads
to the appearance of corns.
The navicular bone and bursa and the tendon of the perforans also suffer
from the effects of compression. The movement of the tendon is restricted,
and arterial supply to the adjacent structures rendered deficient. The
tissues of the bone and bursa are insufficiently nourished, and the
secretion of synovia lessened. In this way it is conceivable that navicular
disease may follow the condition of simple contracted heels.
In common with the other structures, the lateral cartilages also suffer
from the continual pressure. Their blood-supply is lessened, their
functions interfered with, and side-bones result.
_Causes_.--Upon the causation of contraction a very great deal has been
written, both by early veterinarians and by those of the present day. Many
and widely differing opinions have been advanced, but a careful resume of
only a few will lead one to certain fixed conclusions.
We may consider the causes of contraction under two headings--predisposing
and exciting.
_Predisposing Causes of Contraction_.--Among these we will first mention
heredity, although it is possible it should not be deemed of so great
account as it is by some. That the shape of certain feet, especially those
with low heels and abnormally sloping walls, predisposes to contraction no
one will deny. So long, however, as the animal goes unshod, so long does
the foot maintain a normal condition of the heels. In other words, it
is not until the tendency to contraction already there is aggravated by
careless shoeing and the effects of work that it operates to any noticeable
extent.
The degree of contraction will also be very largely governed by the amount
of the development of the frog. With a frog of good size, low down, and
taking part in the pressure of the foot on the ground, contraction will
be prevented. On the other hand, an ill-developed frog, one wasted by
long-continued and spreading thrush, or one robbed of its normal function
by excessive paring in the forge, is a common starting-point of the
condition we are considering. We have already referred to this in Chapter
III., when considering the experiments of Lungwitz in this connection. What
we have to bear in mind in these experiments is that the application of
a pad to the frog, in such a manner that effective ground-pressure is
obtained, results always in a marked expansion of the heels, and that, with
counter-pressure with the ground absent, expansion occurs to little or
no extent. This is proof positive of the enormous part the frog plays in
maintaining an open and elastic condition of the heels--a fact so insisted
on by Coleman.
It is worthy of mention, however, that loss of the frog's function does not
operate to nearly so serious an extent in horses with high, upright heels
as in those with the heels low and excessively sloping.
In illustrating this, Mr. Dollar, in his work on shoeing, mentions the case
of a pair of trotting horses of similar age, size, and weight, each having
weak fore-heels. In one case the hoofs were flat, in the other upright. The
horse with the flat hoofs suffered from contraction, while the other did
not.
The reason appears to be that in the animal with upright hoofs the
proportion of body-weight borne by the heels is considerably less than in
those with the hoofs flat and sloping.
Certain conditions of the horn-producing membranes also predispose to
contraction. For example, in horses reared on marshy soils, and afterwards
transferred to standing in town stables, we find that a dry and brittle
condition of the horn supervenes. This we may regard as a low form of
laminitis, brought about by the heat of the material upon which the animal
is standing, and the congestion of the feet engendered by his enforced
standing for long periods in one position, as opposed to the more or less
continuous exercise when at pasture. With the hoof in this condition it
loses by evaporation the moisture that normally it should contain, and, as
we might expect, a certain degree of contraction of its structure is the
inevitable result.
We thus see that contraction brought about in this way is not so much
caused by the heat of the stable, as it is by the decreased ability of the
horn to retain its own moisture.
On the other hand, it cannot be denied that excessive warmth and dryness
combined tend also to an undue abstraction of moisture, even from the horn
of the healthy foot; and this explains in great measure how it is that
lameness, as a rule, and especially that proceeding from contracted heels,
is far more frequent and of greater intensity in the hot, dry months of
summer, than in the cooler and more humid atmosphere of winter. It is
interesting to note, too, that an alternation of humidity and dryness
is far more liable to injure the quality of the horn and tend to its
contraction than the long-continued effects of dryness alone. A common
illustration of this is to be found in the effects of the ordinary
poultice. Everyone knows that when, after a few days' application, they are
discontinued, we get as a result an abnormally dry and brittle state of
the horn. This is doubtless due to the poultice removing the thin,
varnish-like, and protective pellicle known as the periople, and thereby
allowing the process of evaporation to act on the water normally contained
in the hoof.
_Exciting Causes of Contraction_.--Among these, first place must
undoubtedly be given to shoeing. This does not necessarily imply shoeing
more than ordinarily faulty, nor a faulty preparation of the foot, but
shoeing as it is generally practised. No ordinary shoe, except a few
devised for the purpose, such as the Charlier or the tip, allows the frog
to come in contact with the ground. This we take to be the main factor in
the causation of contracted heels, especially with a predisposition already
present in the foot itself. In the words of Lungwitz: 'Regarded from this
point of view, there is no greater evil than shoeing. It abolishes the
necessary counter-pressure, and thus interferes with expansion. Bars, sole,
and frog cannot perform the functions that naturally belong to them as they
would do without the shoe.'
In addition to the evil of the shoe itself, errors of practice in the forge
contribute to the causation of contraction. Taking first the preparation of
the foot, we find that often the heels are lowered far too much, and the
toe allowed to remain too long. This can have but one effect--that of
throwing a greater proportion of the animal's weight upon the heels than
properly they should bear, with, what we now know to be the consequence of
that, a corresponding pushing inwards and downwards of the horn; in other
words, contraction.
Excessive paring of the bars, to which we have already partly alluded, is
also an active agent in bringing about an inward growth of the horn of the
heels and quarters. The bar, or inflexion of the wall at the heel, by means
of its close contact with the frog, communicates the outward movements
of that organ to the wall of the hoof. With the bar removed, the outward
movements of the frog under pressure are naturally rendered of no account,
and a proper and intermittent expansion of the wall denied it. The same
evil follows, though to a less extent, excessive paring of the sole.
The shape of the bearing surface of the shoe is often to be blamed. Where
this is concave--'seated'--and the 'seating' is carried back to the
heels, it is easy to see that, when weight is on the foot, there is an
ever-present tendency for the bearing edge of the wall to slide down
towards the inner edge of the shoe. This tendency, operating on both the
inner and outer wall simultaneously, must strongly favour contraction.
A further wrong practice is that of continuing the nailing too far towards
the heels. In our opinion this is not now often met with. When it occurs
its effect is, of course, to prevent those movements of expansion of the
wall which we now know to be normal and most marked at the heels.
It may be remarked of the build of the shoe, or of errors in the
preparation of the foot, that neither are of much moment. Neither are
they. But when one stays to consider that errors of this description are
practised not only once, but each time the horse goes to the forge, and
that with some of them--those relating to the build of the shoe--the injury
thereby brought about is inflicted not only once, but every day that
particular shoe is worn, then it is not to be wondered at that, sooner or
later, ill consequences more or less grave result.
_Prognosis_.--This will depend to a very large extent upon the conformation
of the limb, and upon the previous duration of the contraction. Contraction
of long standing, where atrophy of the sub-lying, soft structures and the
pedal bone may be expected, will prove obstinate to treatment. Especially
will this be so if the lateral cartilages have become ossified. Neither may
we look for much benefit from treatment if the contraction has occurred in
animals with an oblique foot axis and flat hoofs.
On the other hand, if the case is comparatively recent, if the limb
is straight and the form of the hoof is upright, and if matters are
uncomplicated by side-bones, or other serious alteration in the internal
structures, then treatment may be rewarded with some measure of success.
[Illustration: FIG. 63.--TIP SHOE. The dotted portions represent the length
of the branches removed.]
_Treatment_.--The greater part of the treatment of contracted foot will
almost suggest itself as a corollary of the causes we have enumerated. The
normal width of the heels may be renewed, and development of the wasted
frog brought about by one of three methods:
1. By restoring the pressure from below to the frog.
2. By the use of an expansion shoe.
3. By operative measures upon the horn of the wall.
1. _By Restoring the Pressure from Below to the Frog_.
This may be accomplished as follows:
_(a) By Shoeing with Tips_.--This method is advocated by Percival, by A.A.
Holcombe, D.V.S., Inspector. Bureau of Animal Industry, U.S.A., by Dollar
in his work on horseshoeing, and by many others.
Though requiring more care than in fitting the ordinary shoe, the
application of a tip is simple. In reality, the tip is just an ordinary
shoe shortened by truncating the heels.
Before applying the tip, the horn of the wall at the toe should be
shortened sufficiently to prevent any undue obliquity of the hoof, and the
foot should be so prepared as to allow the heels of the tip to sink flush
with the bearing edge of the wall behind it.
When the foot does not allow of the removal of much horn at the toe, what
is termed a 'thinned' tip is to be preferred. Its shape is sufficiently
shown by the accompanying figure (Fig. 65).
With the tip the posterior half of the foot is allowed to come into contact
with the ground, and the object we are striving for--namely, frog pressure,
and greater facilities for alternate expansion and contraction of the
heels--is thus brought about.
[Illustration: FIG. 64.--THE TIP SHOE 'LET IN THE FOOT.]
[Illustration: FIG. 65.--THE THINNED TIP.]
_(b) By Shoeing with the Charlier_.--The results brought about by the use
of a tip may be arrived at by the application of a Charlier or preplantar
shoe, or by a modified Charlier or Charlier tip.
Briefly described, a Charlier is a shoe that allows the sole and the frog
to come to the ground exactly as in the unshod foot. This is accomplished
by running a groove round the inferior edge of the hoof by removing
a portion of the bearing edge of the wall with a specially devised
drawing-knife. Into this groove is fitted a narrow and somewhat deep shoe,
made, preferably, of a mixture of iron and steel, and forged in such a
manner that its front or outer surface follows the outer slope of the wall.
The Charlier should have the inner edge of its upper surface very slightly
bevelled, in order to prevent any pressure on the sensitive sole, and
should be provided with from four to six nail-holes. These latter should be
small in size and conical in shape. The nails themselves should be small,
and have a conical head and neck, to fit into the nail-hole of the shoe.
[Illustration: FIG. 66.--THE SPECIAL DRAWING-KNIFE (FLEMING'S) FOR
PREPARING THE FOOT FOR THE CHARLIER SHOE.]
The modified Charlier, or Charlier tip, perhaps the better of the two for
the purpose we are describing, is really a shortened Charlier, and bears
the same relation to the Charlier proper as the tip does to the ordinary
shoe. It is let into the solar surface of the foot in exactly the same
manner as its larger fellow, but it does not extend backwards beyond the
commencement of the quarters. By its use greater opportunity for expansion
is given to the heels than is done by the Charlier with heels of full
length.
[Illustration: FIG. 67.--FOOT PREPARED FOR THE CHARLIER SHOE.]
We do not here intend to deal at any length with the arguments for and
against the Charlier as regards its adoption for general use. These will be
found fully set out in any good work on shoeing.
The point that it is correct in theory it would be idle to attempt to
evade; but that it is generally practicable, or that it offers any very
pronounced advantages, as compared with the disadvantages urged against it,
over the shoes in ordinary use, the limited favour it has drawn to itself,
since its introduction in 1865, seems sufficiently to deny.
_(c) By the Use of a Bar Shoe_.--Where the frog is not excessively wasted
benefit will be derived from the use of a bar shoe.
[Illustration: FIG. 68.--BAR SHOE.]
The transverse portion at the back, termed the 'bar,' and which gives
the shoe its name, is instrumental in bringing about from below that
counter-pressure on the frog that we now know to be so necessary a factor
in remedying contraction. When the frog, by wasting or disease, is
so deficient as to be unable to reach the 'bar,' this shoe must be
supplemented by a leather or rubber sole.
In the event of corn or sand-crack existing with the contraction, the shoe
known as a 'three-quarter bar' is preferable (see Fig. 103). The break here
made in the contour of the shoe allows of dressing the corn, and, in the
case of sand-crack, removes the bearing from that portion of the wall.
_(d) By the Use of a Bar Pad and a Heelless or 'Half' Shoe_.--The bar
pad consists of a shape of rubber composition firmly fixed to a leather
foundation, which shape of rubber takes the place of the 'bar' of the bar
shoe.
[Illustration: FIG. 69.--RUBBER BAR PAD ON LEATHER.]
[Illustration: FIG. 70.--THE BAR, PAD APPLIED WITH A HALF-SHOE.]
For habitual use in such cases as prove obstinate to treatment, or where
a complete cure was never from the commencement expected, the bar pad is
undoubtedly one of the most useful inventions to our hand. The animal's
'going' is improved, the tender frog is protected from injury by loose
stones, and greater comfort given to both the horse and the driver.
[Illustration: FIG. 71.--FROG PAD.]
[Illustration: FIG. 72.--FROG PAD APPLIED.]
_(e) By the Use of a Frog Pad and a Shoe of Ordinary Shape_.--The shape of
rubber on this pad is designed to cover the frog only. Its shape and mode
of application is sufficiently shown in the accompanying illustrations.
_(f) By turning out to Grass_.--Where the expense of keep is no object, a
return of contracted feet to the normal may be brought about by removing
the shoes and turning the animal out to pasture, thus giving the feet the
advantages to be derived from a more or less continuous operation of the
normal movements of expansion and contraction. In this case the treatment
must extend from three to four, or possibly six months.
2. _By the Use of Some Form of Expansion Shoe_.
[Illustration: FIG. 73.--SMITH'S EXPANSION SHOE SEEN FROM ITS GROUND
SURFACE AND FROM THE SIDE. _a_, The screw, with a fine-cut thread; _b_, nut
which travels along it; _c_, a hollow thimble into which the screw passes
at one end, the other being cut out V-shaped to catch into a slot (_d_) on
the shoe; _e, e_, the grip[A] for the bars, the length and direction of
which depend upon the shape of the foot; _f, f_, the counter-sunk rivets
forming the hinge (_f_'); _g_, the counter-sunk rivet of the expanding
piece.]
[Footnote A: The inventor of this shoe uses the word 'grip' to denote what,
in describing other expansion shoes, we term the 'clip' (H.C.R.).]
_(a) Smith's_.--For many years past continental writers have been
practising this method. So far as we know, however, Lieutenant-Colonel Fred
Smith was the first English veterinarian to use a shoe of his own devising,
and to report on its effects. This shoe we will, therefore, give first
mention.
The above figure, with its accompanying letterpress, sufficiently explains
the nature of the shoe. In fitting the shoe, care must be taken to have the
hinges (_f, f_) far enough back, or the shoe will have a tendency to spring
at the heels, and the grips _(e, e)_, which catch on the bars, will have
a difficulty in biting. This trouble will be avoided by having the hinges
about 1-1/2 to 2 inches from the heels.
After the shoe has been firmly nailed to the foot, the travelling nut _b_
is driven forward on the screw _a_ so as to cause the grips to just catch
on the inside of the bars of the foot. According to the inventor, the
amount of pressure to be exerted must be learned by experience, and he
says:
'I screw up very gradually until I see the cleft of the frog just beginning
to open. I now trot the horse up, and if he goes sound it is certain that
the pressure I have exercised will not give rise to trouble. The animal is
sent to work to assist in the expansion of the foot. On examining the shoe
next day, the grip is found to be quite loose, the foot has enlarged, and
the nut is turned once more until the grip on the bars is tightened, the
horse being again trotted to ascertain that no injurious pressure is
exerted.
'Every day or two I repeat this process, making measurements in all cases
before widening the heels. The increase in width of the foot which results
is astonishing, 1/4 to 3/8 inch during the first week may be safely
predicted, and in a month to six weeks it is impossible to recognise in the
large healthy frog and wide heels, the shrivelled-up organ of a short time
before.'[A]
[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. v.,
p. 98.]
It is pointed out by the writer of the above (and his observations,
doubtless, apply to the use of all other expansion shoes in which the bars
are gripped and forcibly expanded) that the whole secret of success lies
in avoiding injurious pressure by exerting too great an expansion at one
operation. After each manipulation of the expanding apparatus the horse
should trot sound and the frog remain cool. Should the foot become hot, and
lameness supervene, then tension should at once be relaxed.
_Recorded Cases of the Use of the Shoe_.--The inventor of the shoe relates
two cases of contracted foot treated by these means in which the heels
of one, after thirty-nine days' treatment, had increased in width to the
extent of 1 inch, and the heels of the other, after twenty-four days', had
enlarged 5/8 inch. Of the first case he gives the drawings in Fig. 74.
A represents the foot before treatment; B the same foot after nine days'
treatment, when the heels had widened 3/4 inch; and C the same foot at
the end of the thirty-nine days' treatment, at which date the frog was an
excellent-looking one, and the foot had increased an inch in width.[A]
[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. v.,
p. 100]
[Illustration: FIG. 74.--THE CHANGES IN FORM OF A CONTRACTED FOOT TREATED
WITH SMITH'S EXPANSION SHOE]
In 1893, at a meeting of the Midland Counties Veterinary Medical
Association, the late Mr. Olver said he had applied this shoe to a valuable
hunter that had gone so lame that he could scarcely put his foot to the
ground. After a fortnight's application, and by the assistance of the
double screw in the shoe, the heel was forced out. Then the horse was put
to work with the shoe on, and he had hunted the whole of the last season in
a perfectly sound condition.[A]
[Footnote A: _Veterinary Record_, vol. vi., p. 143]
F.D. McLaren, M.R.C.V.S., writes:[A] 'I resolved to try one of Captain
Smith's shoes in a case where the hoof was badly contracted, and where the
frog had entirely disappeared, there being also slight lameness. The roof
rapidly expanded, and every other day the nut was moved on a bit to keep
the cross-piece tight. I then had the cross-piece bent downwards a little
_to prevent the nut pressing on the rapidly-growing frog_.[B] After another
fortnight or so, I had a shoe made with clips resting against the inside of
the bars,[C] and the next time he was shod these were also dispensed with.
It is now a year ago since the animal recovered his frog, and he still has
the largest frog in the stable, and the hoof shows no sign of contraction.'
[Footnote A: _Ibid_., vol. vi., p. 183]
[Footnote B: The italics are mine (H.C.R.).]
[Footnote C: The expanding shoe itself was here evidently dispensed with,
and an ordinary shoe with bar-clips used in its stead (H.C.R.).]
_(b) De Fay's_.--Among other shoes of the expansion class may be mentioned
that of De Fay. Like the preceding, it is a shoe with a flat bearing
surface, and provided with bar-clips. It is, however, _un_ hinged. The
requisite degree of periodic expansion is in this case arrived at by a
forcible widening of the heels of the shoe, accomplished by bending
the substance of which it is made, and for this purpose the instrument
illustrated in Fig. 75 is employed.
The foot is first properly trimmed by levelling the heels and thinning
the sole on each side of the frog. The shoe is then fixed by nails in the
ordinary manner, taking care that the last nails come not too far back, and
that the clips rest evenly and firmly on the inside of the bars.
The dilator, hoof-spreader, or vice, as it is variously called, is then
applied, its two jaws (_a_ and _b_) fitting against the inner edge of
the shoe at the heels. Careful note is taken of the width of the hoof as
measured on the graduated scale (_e_, _e_), and the double screw (_g_, _h_)
revolved by means of the wrench (k), until the opening of the jaws thus
obtained registers an expansion of 1/12 to 1/8 inch.
The dilatation is repeated at intervals of from eight to ten days, until,
at the expiration of a month or six weeks, the amount of total expansion of
the heels registers nearly an inch. That the method requires the greatest
care may be gathered from the reports of continental writers. They state
that frequently the pain and consequent lameness keep the patient confined
to the stable for several days.
Numerous and but slightly differing forms of the dilator are on the market.
As in principle they are all essentially the same, and are to be found
illustrated in any reliable instrument catalogue, they need no description
here.
[Illustration: FIG. 75.--DE FAY'S VICE.]
_(c) Hartmann's_.--A further useful expansion shoe is that of Hartmann's
(Fig. 76), in that it may be adapted for either unilateral or bilateral
contraction. This shoe is also provided with bar-clips, and forcibly
expanded at the heels by means of a dilator. The expansion is governed by
saw-cuts through the inner margin of the shoe directed towards its outer
margin, and running only partially through the inner half of the web (see
Fig. 76).
According as the contraction is confined to the inner or outer heel, the
saw-cuts, one or two in number, are placed to the inner or outer side of
the toe-clip. When the contraction is bilateral, the saw-cuts, one or more
in number, are placed on each side of the toe-clip.
_(d) Broue's_.--This is one of the forms of so-called 'slipper' shoes (see
Fig. 77). We have already indicated that the shape of the bearing surface
of the ordinary shoe--by its 'seating' or sloping from outside to
inside--is sometimes a cause of contraction. In the 'slipper' of Broue
this bearing is reversed, and the slope is from inside to outside. In
the original form of this shoe the slope to the outside was continued
completely round the shoe. Experience taught that the strain this enforced
upon the junction of the wall with the sole was injurious, and that the
'reversed seating,' if we may so term it, was best confined to the hinder
portions of the shoe's branches.
[Illustration: FIG. 76. This figure illustrates the principle of the
Hartmann expanding shoe. _a, a_, The clips to catch the inside of the bars;
_b, c_, saw-cuts.]
The amount of slope should not be excessive. If it is, too rapid and too
forcible an expansion takes place, and pain and severe lameness results.
Dollar gives the requisite degree of incline by saying that the outer
margin of the bearing surface of the shoe should be from 1/12 to 1/8 inch
lower than the inner.
In the case of the Broue slipper, it is the animal's own weight that brings
about the widening of the heels, the slope or outward incline of the
slipper simply causing the inferior edge of the wall at the heels to spread
itself outwards instead of sliding inwards on the bearing surface of the
shoe.
[Illustration: FIG. 77.--THE SLIPPER SHOE OF BROUE.]
_(e) Einsiedel's_.--Like the 'slipper' of Broue, the Einsiedel shoe depends
for its effects upon the slope of the bearing surface.
It differs from the Broue in being provided with a 'bar-clip.' This, in
addition to gripping the bars like the bar-clips of other expanding
shoes, also assists, under the body-weight, in expanding the heels by the
pronounced slope given to its upper surface. The expanding force exerted
by the body-weight falls thus, through the medium of the bar-clip, clip,
_partly_ upon the bars, instead of, as in the Broue, solely upon the wall.
We say _partly_ advisedly, for, in addition to the slope upon the outer
side of the bar-clips, the bearing surface of the heels of the shoe is
_slightly_ sloped outwards also. The good office served by the bar-clip is
the lessening of any tendency to strain upon the white line.
[Illustration: FIG. 78.--THE SLIPPER AND BAR-CLIP SHOE OF EINSIEDEL.]
Those we have described by no means exhaust the number of expansion shoes
that have been devised. There are numerous others, many of which are
composed of three-hinged portions, the two hindermost of which are
gradually separated by a toothed arrangement of their inner margins and
a travelling bar, the disadvantage of which is that it is liable to work
loose. In the majority of this class of shoe the hinges are placed far
forward, one on each side of the toe. They there become exposed to
excessive wear. In fact, against the bulk of this form of shoe it may
be urged that they cannot be worn by the animal at work, that they are
expensive, difficult to make, and easily put out of order.
3. _By Operations on the Horn of the Wall_.
_(a) Thinning the Wall in the Region of the Quarters_.--This is best
done by means of an ordinary farrier's rasp. The thinning should lessen
gradually from the heel for 2-1/2 to 3 inches in a forward direction. That
portion of the wall next to the coronary border, about 1/2 inch in breadth,
should not be touched. At this point the thinning should commence, should
be at its greatest, and lessen gradually downwards until at the inferior
margin of the wall the normal thickness of horn is left. The animal is then
shod with a bar shoe and the hoof bound with a bandage soaked in a mixture
of tar and grease, in order to keep the thinned portion of the wall from
cracking. In this condition the animal may remain at light labour.
When possible, however, it is better to combine the thinning process thus
described with turning out to grass. In this case the ordinary shoe is
first removed, and the foot poulticed for twenty-four hours to render
the horn soft. The foot is then prepared by slightly lowering the
heels--leaving the frog untouched--and thinning the quarters in exactly the
manner described above.
After this is done, the animal is shod with an ordinary tip, a sharp
cantharides blister applied to the coronet, and then turned out in a damp
pasture. In this case the object of the tip is to throw the weight on
to the heels and quarters. The thinned horn yields to the pressure thus
applied, and a hoof with heels of a wider pattern commences to grow down
from the coronet. Two to three months' rest is necessary before the animal
can again he put to work.[A]
[Footnote A: This is the treatment strongly advocated by A.A. Holcombe,
D.V.S., Inspector, Bureau of Animal Industry, U.S.A.]
_(b) Thinning the Wall in the Region of the Toe_.--This is done with
the idea that the tendency of the heels to expand under pressure of the
body-weight is helped by the thinned portion at the toe allowing the heels
to more readily open behind. Seeing that in the case of toe sand-crack the
converse is argued--that contraction of the heels readily takes place and
forces the sand-crack wider open--it is doubtful whether this method is of
any utility in treating contracted heels.
_(c) Grooving the Wall Vertically or Horizontally, and Shoeing with a Bar
Shoe_.--Marking the wall with a series of grooves, each running in a more
or less vertical direction, was suggested to English veterinarians by
Smith's operation for side-bones.
The manner of making the grooves, and the instruments necessary, will be
found fully described in Section C of Chapter X.
That the method is followed by satisfactory results the undermentioned case
will show:
'A mare, which I have had in my possession since she was a foal, has always
had contracted feet, which were also unnaturally small.... Lately the mare
has been going very "short," and at length her action was quite crippled.
At times she was decidedly lame on the off fore-foot. At no time have I
been able to detect any sign of structural disease. I thereupon concluded
that the lameness was due to mechanical pressure on the sensitive
structures, and I determined to try the effects of the above treatment. As
this was my first experience of the process, I was careful to carry it out
in all its details, as described by Professor Smith. After the bar shoes
had been put on, the mare was very lame. I allowed her two days' rest, then
commenced regular walking exercise, and she daily improved. After fourteen
days there was no lameness, but still short action. I thereupon gave the
mare another week's walking exercise, at the expiration of which I drove
her a short turn of five miles, which she did quite well, and free from
lameness. For three months I kept the saw-cuts open to the coronet, and
continued the bar shoes, keeping the mare at exercise, and giving her
occasionally a drive. She never liked the bar shoes, and I was glad when I
could discontinue them, which I did in the fourth month. When shod with the
usual shoes the complete success of the treatment was shown. I have now had
her going with the ordinary shoes for the past two or three months, and the
improvement in the shape of the feet is very marked; there is no lameness;
the mare is free in movement, fast, and spirited, whereas previously she
was quite the reverse, and almost unfit to drive.'[A]
[Footnote A: W.S. Adams, M.R.C.V.S., _Veterinary Journal_, vol. xxx., p.
19.]
This method, though but recently introduced to the English veterinary
surgeon, is by no means new. According to Zundel, it was recently made
known on the Continent by Weber, but was previously known and mentioned by
Lagueriniere, Brognier, and Hurtrel d'Arboval.
When the grooving is in a horizontal direction, a single incision is
sufficient. This is made 3/4 inch below the coronary margin of the wall,
and parallel with it, extending from the point of the heel for 2 or 3
inches in a forward direction. As in the previous method, a bar shoe is
applied, and the animal daily exercised. Thus separated from the fixed
and contracted portion of the wall below, the more elastic coronet under
pressure of the body-weight commences to bulge. The bulging is of such
an extent as to cause the new growing hoof from the top to considerably
overhang the contracted portion below, and cure of the condition results
from the newly-expanded wall above growing down in a normal direction.
This consideration of contracted heels may be concluded by drawing
attention to the advisability of always maintaining the horn of the wall in
as soft and supple a condition as is natural by the application of suitable
hoof dressings.
A useful one for the purpose is that made with lard, to which has been
added a small quantity of wax or turpentine.
Especially should a dressing like this be used when the hoof is inclined
to be hard and brittle, and where tendency to contraction has already been
noticed.
The application of a hoof ointment is also particularly indicated where the
foot is much exposed to dampness, where the animal is compelled to stand
for long periods upon a dry bedding, or where the bedding is of a substance
calculated to have a deleterious effect upon the horn.
This, in conjunction with correct shoeing, will probably serve to avoid the
necessity for more drastic measures at a later time.
_(b)_ LOCAL OR CORONARY CONTRACTION.
_Definition_.--Contraction at the heels, confined to the horn immediately
succeeding that occupied by the coronary cushion. Really, the condition is
but a somewhat arbitrary subdivision of contracted hoof, as we have just
described it in general. For that reason we shall give it but very brief
mention.
_Symptoms_.--In this case the horn of the heels, instead of running down
in a straight line from the coronary margin to the bearing surface of the
wall, presents a more or less distinct concavity (See Fig. 79, _a_, _a_).
As is the case with contraction considered as a whole, this deformity may
affect one or both heels; and during its first appearance, which is after
the first few shoeings, the animal may go distinctly lame.
_Causes_.--Coronary contraction may occur in hoofs of normal shape
immediately shoeing is commenced, and frog pressure with the ground
removed. It is far more likely to ensue, however, if the hoof is flat,
with the heels low, and the wall sloping. And with those predisposing
circumstances it is that the horse goes lame, and not with the hoof of
normal shape.
Seeing, then, that this condition is largely dependent upon the shape of
the foot, we may, to some extent, regard it as hereditary. Seeing further,
however, that it only appears when shoeing is commenced, we may in a
greater degree also regard it as acquired. The lesson, therefore, that this
and other forms of contraction should teach us is the carefulness with
which the shoeing should be superintended in a large stud, or in any case
where the animal is of more than ordinary value.
[Illustration: FIG. 79.--HOOF WITH LOCAL OR CORONARY CONTRACTION (AS
INDICATED AT THE POINTS _a, a_).]
The explanation of the restricted nature of this form of contraction
is simple enough. We have only to refer to the lessons taught by the
experiments of Lungwitz, described in Chapter III., and the condition
almost explains itself. We remember that, briefly, the coronary margin of
the wall resembles a closed elastic ring, which yields and expands to
local pressure, no matter how slight. We remember also that removal of the
counter-pressure of the frog with the ground tended to contraction of the
wall's solar edge when weight was applied. Connect these two facts with
the experience that this form of contraction more often than not occurs in
hoofs with sloping heels, and we arrive at the following:
1. The excessive slope of the heels tends to throw a more than usual part
of the body-weight upon the posterior portion of the coronary margin of
the wall, with a consequent expansion of that part of the coronary margin
implicated.
2. That the shoeing, in removing the counter-pressure of the frog with the
ground, is at the same time tending to bring about contraction of the lower
portions of the wall at the heels and quarters.
3. That this tendency to contraction will at first appear in the thinner
portion of the area of wall named--namely, in that immediately below the
bulging coronary margin.
We thus get the appearance depicted in Fig. 79--a contraction _(a, a)_ of
the heels in the horn below the coronary margin, with the coronary margin
itself bulging above, and a hoof of apparently normal width below.
We say 'apparently' with a purpose, for, as actual measurements will show,
the wall near the solar edge is really contracting, for reasons which we
have just described connected with shoeing. Its 'appearance' of normal
width is accounted for thus: The contraction at _a, a_ is caused by the
dragging inwards of the coronary cushion brought about by the sinking
downwards of the plantar cushion, with which body it will be remembered the
coronary cushion is continuous. With the constant dragging in and down
of the coronary cushion there is given, to the horn-secreting papillae,
studding both the lower third of its outer face and its lowermost surface,
a distinct 'cant' outwards. Below the lowermost limit of the coronary
cushion, then, by reason of the cant outwards of the coronary papillae
in the situations mentioned, the horn of the wall takes a more outward
direction than normal, a fact which lessens in effect the contraction as a
whole really going on. It is interesting, too, to note that by this outward
cant of the wall below, and the bulging of the coronary margin above it,
the contraction (_a, a_) is heightened in effect, and caused to appear
greater than really it is.
From what we have said it follows that contraction of the heels, excepting
the extreme coronary margin, is existent generally, and not confined solely
to _a, a_.
We have, then, in this condition, as we indicated at the commencement,
but a phase in the evolution of ordinary contracted heels, for, with the
progress of the contraction already existing at _a, a_, and below those
points, it is only fair to assume that with it falling in of the at present
bulging coronary margin must sooner or later occur, that, though expanded
when compared with the wall below it, it will be really contracted as
compared with what it was once in that same foot.
We may therefore conclude this section by remarking that factors tending to
contraction of the heels in general are equally potent in the causation of
contracted coronet alone.
_Treatment_.--Exactly that described for contracted heels. Bearing in mind
that contracted coronary margin is but the onset of contracted heels, and
that its first exciting cause is that of removal of the ground-pressure
upon the frog, the most careful attention must be paid to the shoeing. The
use of bar shoes, ordinary frog pads, or heelless shoes and bar pads, are
especially indicated, together with abundant exercise. By these means the
normal movements of expansion will be brought into play, and the condition
quickly remedied.
C. FLAT-FOOT.
_Definition_.--By this term is indicated a condition of the foot where the
natural concavity of the sole is absent.
_Symptoms_.--In the flat-foot the inferior edge of the wall, the sole,
and the frog, all lie more or less in the same plane. It is a condition
observed far more frequently in fore than in hind limbs, and is seen in
connection with low heels, more or less obliquity of the wall, and a
tendency to contraction. The action of the animal with flat feet is heavy,
a result partly of the build of the foot, and partly of the tenderness that
soon comes on through the liability of the sole to constant bruising.
[Illustration: FIG. 80. This figure represents the lower surface of a
typical flat-foot. It illustrates, too, the commencement of a condition we
referred to in Section B of this chapter--namely, the compression of the
frog by the ingrowing heels (b) and bars (a).]
_Causes_.--Flat-foot is undoubtedly a congenital defect, and is seen
commonly in horses of a heavy, lymphatic type, and especially in those
bred and reared on low, marshy lands. It is thus a common condition of the
fore-feet of the Lincolnshire shire.
As might be expected, a foot of this description is far more prone to
suffer from the effects of shoeing than is the foot of normal shape, and
regarded in this light shoeing may be looked upon as, if not an actual
cause, certainly a means of aggravating the condition. Directly the
shoe--or at any rate the ordinary shoe--is applied, mischief commences. The
frog is raised from the ground, and the whole of the weight thrown on to
the wall. The heels, already weak and inclined to turn in, are unable to
bear the strain. They _turn in_, and contraction commences. This 'turning
in' of the heels is favoured by the undue obliquity of the wall. At the
same time, the sole being archless, a certain amount of elasticity is
lost. The weight is thrown more on to the heels, and the os pedis slightly
descends, rendering the flatness of the sole even more marked than before.
With the loss of elasticity of the sole concussion makes itself more felt.
The animal is easily lamed, bruised sole becomes frequent, and corns sooner
or later make their appearance.
_Treatment_.--Flat-foot is incurable. All that can be done is to pay
careful attention to the shoeing, and so prevent the condition from being
aggravated. In trimming the foot the sole should not be touched; the frog,
too, should be left alone, and the wall pared only so far as regards broken
and jagged pieces.
The most suitable shoe is one _moderately_ seated. If the seating is
excessive, and bearing allowed only on the wall, there is a tendency for
the wall to be pushed outwards, and for the sole to drop still further. On
the other hand, if the seating is insufficient, or the web of the shoe too
wide, and too great a bearing thus given to the sole, then we get, first,
an undue pressure upon the last-named portion of the foot a bruise, and,
finally, lameness. The correct bearing should take in the whole of the wall
and the whole of the white line, and should _just impinge_ upon the sole.
Above all, the heels of the shoe should be of full length, otherwise, if
the shoe is worn just a little too long, its heels are carried under the
sole of the foot, and by pressure there produce a corn.
If, with these precautions in shoeing flat-foot, tenderness still persists,
a sole of leather or gutta-percha must be used with the shoe.
D. PUMICED-FOOT, DROPPED SOLE, OR CONVEX SOLE.
_Definition_.--This term is applied to the foot when the shape of the sole
is comparable to the bottom of a saucer. When least marked it is really an
aggravated form of flat-foot.
_Symptoms_.--In pumiced-foot the sole projects beyond the level of the
wall. The obliquity of the latter is more marked than in the previous
condition, and progression, to a large extent, takes place upon the heels.
In addition to its deformity, the horn is greatly altered in quality, and,
as the name 'pumice' indicates, is more or less porous in appearance,
bulging, and brittle.
_Causes_.--As a general rule, it may be taken that pumiced-foot is a sequel
of previous disease, although in its least pronounced form it may occur as
the result of accidental or other causes, such as those described in the
causation of flat-foot.
Occurring in its most marked form, there is no gainsaying the fact that
pumiced-foot is a sequel of either acute or subacute laminitis. As we shall
see when we come to study that disease, the dropping of the sole is brought
about by distinct and easily-understood morbid processes affecting the
sensitive structures. Briefly, these morbid processes in laminitis may be
described thus: The accumulated inflammatory exudate, and in some cases
pus, weakens and destroys the union between the sensitive and insensitive
laminae. This separation, for reasons afterwards to be explained, is
greatest in the region of the toe. The os pedis, loosened from its intimate
attachment with the horny box, is dropped upon the sole, and the sole,
unable to bear the weight, commences to bulge below.
The altered character of the horn is accounted for by the inflammatory
changes in the sensitive laminae and the papillae of the keratogenous
membrane generally, for it follows as a matter of course that these
tissues, themselves in a diseased condition, must naturally produce a horn
of a greatly altered and inferior quality.
When following the _subacute_ form of laminitis, the changes characterizing
pumiced-foot are slow in making their appearance. The animal at first goes
short, and the lameness thus indicated gradually becomes more severe, until
the animal is no longer able to work. The feet become hot and dry, the
hoof loses its circular form, and the growth of horn at the heels becomes
excessive. At this stage the appearance of bulging at the sole begins to
make itself seen. Later, the outer surface of the wall becomes 'ringed' or
'ribbed,' the rings being somewhat closely approximated in the region of
the toe, and the distance between them gradually widening towards the
heels. The wall too, especially in the region of the toe, instead of
running in a straight line from the coronary margin to the shoe, becomes
concave. It is this change, together with the appearance of the rings, that
indicates the loosening of the attachment of the os pedis to the wall, and
its afterwards backward and downward direction (see Fig. 124).
[Illustration: FIG. 81.--HOOF WITH THE RIBS OR RINGS CAUSED BY CHRONIC
LAMINITIS.]
As a sequel of _acute_ laminitis, these changes make their appearance with
more or less suddenness, and are generally complicated in that they owe
their occurrence to the formation of pus within the horny box.
_Treatment_.--Pumiced-foot is always a serious condition. The animal is
useless for work upon hard roads or town pavings, and is of only limited
utility for slow work upon soft lands. The more serious form, that
following acute laminitis, and complicated by the presence of pus, we may
regard as beyond hope of treatment.
With the more simple form of the condition, we may do much to render
greater the animal's usefulness. The same principles as were applied to the
shoeing of flat feet will have to be observed here. Trimming or paring
of any kind, save 'straightening up' of the wall, must be severely
discountenanced. A broad-webbed shoe, one that will give a certain amount
of cover to the sole, is indicated. As in the treatment of flat-foot,
however, direct pressure upon the sole must be avoided, and the shoe
'seated.' The 'seating,' however, should not commence from the absolute
outer margin of the shoe's upper surface. A _flat_ bearing should be given
to the wall and the white line, and the seating commenced at the sole.
We have already remarked on the increased growth of horn at the heels. It
is in this position, then, that will be found the greatest bearing surface
for the shoe, and it is wise, in this case, to have the heels of the shoe
kept flat. In other words, the 'seating' is not to be continued to the
hindermost portion of the branches of the shoe. By this means there may be
obtained at each heel a good solid bearing of from 2 to 3 inches, which
would otherwise be lost.
Where the accompanying condition of the horn is bad enough to indicate it,
a leather sole should be used, beneath which has been packed a compress of
tow and grease, rendered more or less antiseptic by being mixed with tar.
Where the sole is exceedingly thin, and inclined to be easily wounded, and
where the hoof, by its brittleness, has become chipped and ragged at the
lower margin of the wall, it may perhaps be more advantageous to use, in
place of the compress of tow, the _huflederkitt_ of Rotten. This is a
leather-like, dark brown paste. When warmed in hot water, or by itself, it
becomes soft and plastic, and may readily be pressed to the lower surface
of the foot, so as to fill in all little cracks and irregularities, and
furnish a complete covering to the sole and frog, and to the bearing
surface of the wall. When cold it hardens, without losing the shape given
to it, into a hard, leather-like substance.
Treated in this way, the animal with pumiced feet may yet be capable of
earning his living at light labour or upon a farm.
E. 'RINGED' OR 'RIBBED' HOOF.
_Definition_.--A condition of the hoof in which the wall is marked by a
series of well-defined ridges in the horn, each ridge running parallel with
the coronary margin. They are known commonly as 'grass rings,' and may be
easily distinguished from the more grave condition we have alluded to as
following laminitis, by the mere fact that they do not, as do the laminitic
rings, approximate each other in the region of the toe, but that they run
round the foot, as we have already said, _parallel with each other_.
[Illustration: FIG. 82.--HOOF SHOWING THE RINGS IN THE HORN BROUGHT ABOUT
BY PHYSIOLOGICAL CAUSES.]
_Causes_.--This condition is purely a physiological, and not a pathological
one, and the words of its more common name, 'grass rings,' sufficiently
indicate one of the most common causes. Anything tending to an alternate
increase and decrease in the secretion of horn from the coronet will bring
it about. Thus, in an animal at grass, with, according to the weather
conditions, an alternate moistness and dryness of the pasture, with its
consequent influence on the horn secretion, these rings nearly always
appear. The effects of repeated blisters to the coronet make themselves
apparent in the same way, and testify to the efficacy of blisters in this
region in any case where an increased growth of horn is deemed necessary.
From this it is clear that the condition depends primarily upon the
amount and condition of the blood supplied to the coronary cushion. Thus,
fluctuations in temperature during a long-continued fever, or the effects
of alternate heat and cold, or of healthy exercise alternated with
comparative idleness, will each rib the foot in much the same manner.
_Treatment_.--The condition is so simple that we may almost regard it
as normal. Consequently, treatment of any kind is superfluous. Where
constitutional disturbance is exerting an influence upon either the quality
or quantity of the blood directed to the part, then, of course, attention
must be paid to the disease from which it is arising.
F. THE HOOF WITH BAD HORN.
(_a_) THE BRITTLE HOOF.
_Definition_.--As the name indicates, we have in this condition an
abnormally dry state of the horn.
_Symptoms_.--These are obvious. The horn is hard, and when cut by the
farrier's tools gives the impression of being baked hard and stony, the
natural polish of the external layer is wanting, and there is present,
usually, a tendency to contracted heels. With the dryness is a liability to
fracture, especially at points where the shoe is attached by the nails.
As a consequence, the shoes are easily cast, leading to splits in the
direction of the horn fibres. These run dangerously near the sensitive
structures, giving rise in many cases to lameness. Even where pronounced
lameness is absent the action becomes short and 'groggy,' and the utmost
care is required in the shoeing to keep the animal at work.
_Causes_.--To a very great extent the condition is hereditary, and is
observed frequently in animals of the short, 'cobby' type. In ponies
bred in the Welsh and New Forest droves the condition is not uncommon,
especially in the smaller animals. Animals who have had their feet much
in water--as, for instance, those bred and reared on marshy soils--and
afterwards transferred to the constant dryness of stable bedding, are also
particularly liable to this condition. It is noticed, too, following the
excessive use of unsuitable hoof-dressings, more especially in cases where
coat after coat of the dressing is applied without occasionally removing
the previous applications.
_Treatment_.--As a prophylactic, a good hoof-dressing is indicated. It
should not consist solely of grease, but should have mixed with it either
wax, turpentine, or tar.
Above all, careful shoeing should be insisted on, and the owner of an
animal with feet such as these will be well advised if he is recommended to
have the shoeing superintended by one well competent to direct it rightly.
The foot should be trimmed but lightly, always remembering that in a foot
of this description the horn, in addition to being brittle, is generally
abnormally thin. Jagged or partly broken pieces should be removed, and the
bearing surface rendered as level as possible. The foot should be carefully
examined before punching the nail-holes in the shoe, and the nail-holes
afterwards placed so as to come opposite the soundest portions of horn. The
nails themselves should be as thin as is consistent with durability, and
should be driven as high up as possible.
On the least sign of undue wear the shoes should be removed, never, as is
too often done, allowing them to remain on so long that a portion breaks
away. If, with the laudable idea of not interfering with the horn more than
is possible, this is practised, the portion of the shoe breaking off is
bound to tear away with it more or less of the brittle horn to which it is
attached.
Where the breaks in the horn are so large as to prevent a level bearing for
the shoe being obtained, the interstices should be filled up with one or
other of the preparations made for this purpose. One of the most suitable
is that discovered by M. Defay. By its means sand-cracks or other fractures
of the horn may be durably cemented up.
'Even pieces of iron may be securely joined together by its means. The only
precaution for its successful application is the careful removal of all
grease by spirits of sal-ammoniac, sulphide of carbon, or ether. M. Defay
makes no secret of its composition, which is as follows: Take 1 part of
coarsely-powdered gum-ammoniac, and 2 parts of gutta-percha, in pieces the
size of a hazel-nut. Put them in a tin-lined vessel over a slow fire, and
stir constantly until thoroughly mixed. Before the thick, resinous mass
gets cold mould it into sticks like sealing-wax. The cement will keep
for years, and when required for use it is only necessary to cut off a
sufficient quantity, and remelt it immediately before application. We have
frequently used this cement for the repair of seriously broken hoofs. It is
so tenacious that it will retain the nails by which the shoe is attached
without tearing away from the hoof.'[A]
[Footnote A: _Veterinary Journal_, vol. iii., p.71.]
Failing this, the bearing surface may be made level, and fractures repaired
by using the _huflederkitt_ described in the treatment of pumiced sole.
(_b_) THE SPONGY HOOF.
_Definition_.--This is the opposite condition to the one we have just
described, and is characterized by the soft and non-resistant qualities of
the horn.
_Symptoms_.--Spongy hoof is quite common in animals that have large, flat,
and spreading feet--in fact, the two appear to run very much together. It
is a common defect in animals reared in marshy districts, and of a heavy,
lymphatic type. The Lincolnshire Shire, for instance, has often feet
of this description, and, the causative factors being in this case
long-continued, render the feet extremely predisposed to canker. The horn
is distinctly soft to the knife, and has an appearance more or less greasy.
Animals with spongy feet are unfit for long journeys on hard roads. When
compelled to travel thus, the feet become hot and tender, and lameness
results. A mild form of laminitis, extending over a period of three or
four days, often follows on this enforced travelling on a hard road, more
especially in cases where the animal is 'heavy topped,' and the usual
food of a highly stimulating nature. In fact, it has been the author's
experience to meet with this condition several times in the case of shire
stallions doing a long walk daily upon hard roads, with the weather hot and
dry.
_Treatment_.--When a horse with spongy feet is shod for the first time,
care must be taken to avoid excessive paring of the sole, for already the
natural wear of the foot has been sufficient to keep the soft horn in a
state of thinness. For the same reason hot fitting of the shoe must not
be indulged in for too long a time. That common malpractice of the forge,
'opening up the heels,' must, in this case, be especially guarded against,
or the excessive paring of the frog and partial removal of the bars that
this operation consists in will lay the foot open to risk of contraction.
To begin with, the heels are naturally weak, and, once the bars are
removed, there is nothing to prevent them rapidly caving in towards the
frog. Even when carefully shod, a foot of this class is readily prone to
contract directly the animal is brought into the stable, and the horn
commences to dry to excess. An ordinary light shoe should be used, and the
nails should be light and thin. They should be driven carefully home, and
the 'clinching' made as tight and secure as possible.
G. CLUB-FOOT.
_Definition_.--Under this name we indicate all cases in which the horn
of the wall become straightened from above to below. It will, therefore,
include all conformations varying from the so-called 'upright hoof,' in
which the toe forms an angle of more than 60 degrees with the ground, to
the badly 'clubbed' foot, in which the horn at the toe forms a right angle
with the ground, or is even directed obliquely backwards and downwards, so
that the coronary margin overhangs the solar edge of the wall.
[Illustration: FIG. 83.--THE CLUB-FOOT.]
_Symptoms_.--Even in its least pronounced form the condition is apparent at
a glance, the alteration in the angle formed by the hoof with the ground
striking the eye at once, and the heels, as compared with the toe,
appearing much too high. When the condition is slight, the wall of the toe
is about twice as high as that of the heels, while in the most marked form
the toe and the heels may in height be nearly equal (see Fig. 83). When
congenital, but little interference with the action is noticed. Such
animals, by reason of their 'stiltiness,' are unfit for the saddle, but at
ordinary work will perform their duties equally well with the animal of
normal-shaped feet. When acquired as the result of overwork, of contracted
tendons, or other causes, however, the gait becomes stumbling and
uncertain. The body-weight is transferred from the heels to the anterior
parts of the foot, and the shoe shows undue signs of wear at the toe.
_Causes_.--Upright hoof is undoubtedly hereditary, and is even seen as a
natural conformation in the feet of asses and mules. When hereditary in the
horse, however, it is certainly a defect, and is associated commonly with
an upright limb, and a short, upright pastern (see Fig. 83).
Among other causes, we may enumerate sprains or wounds of the flexor
tendons, or any disease of the limbs for a long time preventing extension
of the fetlock-joint, such as sprains or injuries of the posterior
ligaments of the limb, splints or ringbones so placed as to interfere with
the movements of the flexor tendons, or, in the hind-limb, spavin, keeping
for some months the fetlock in a state of flexion. In the very young animal
the condition may be induced by an improper paring of the foot--cutting
away too much at the toe, and allowing the heels to remain.
_Treatment_.--When the condition is congenital, no treatment at all is
indicated. It might, in fact, be said that interference would tend rather
to minimize than enhance the animal's usefulness; for, in this case, the
club-shaped feet are in all probability due to faulty conformation above.
In other words, the upright hoof is in this instance but a natural result
of the animal's build, with which useful interference is impossible.
Where the upright hoof is a consequence of excessive paring of the toe,
or insufficient removal of the heels, the condition may be remedied by
directing attention to those particulars, and preventing their continuance.
At the same time, a greater obliquity of the limb axis may be given by the
use of a suitable shoe. The shoe indicated is a short one, with thin heels
and a thick toe. In some cases the abnormality may be remedied by the use
of a tip. Whatever method is adopted, care must be taken not to attempt
too positive a change in the direction of the limb at one operation. The
process must be gradual.
In cases where the abnormality has been brought about by wounds to the
flexor tendons, the alteration in the direction of the limb is often so
great as to produce 'knuckling over' of the fetlock. This, to a very great
extent, may be remedied by the use of a shoe with calkins and an extended
toe-piece (see Fig. 84).
[Illustration: FIG. 84.--THE SHOE WITH EXTENDED TOE-PIECE AND HIGH
CALKINS.]
With this shoe a certain amount of forced exercise is advisable, and at
intervals of about two weeks the calkins should be somewhat lowered, until
the heels are brought as close to the ground as is possible. In giving
directions for this shoe to be made the veterinary surgeon must, when
referring to the length of the toe-piece, be guided entirely by the
condition of the case. Ordinarily, a suitable length is from 3 to 4 inches.
It is necessary also to warn the owner that, by reason of the length
projecting, the shoe is liable to be torn off.
Should the 'knuckling over' have become complicated by bony deposits round
the seat of the original injury, then a favourable modification of the
condition is not so likely to result.
The benefit to be derived from the shoe with an extended toe-piece in a
case of excessive knuckling is admirably shown in a brief report of a case,
under the title of 'Hooked Foot,' in vol. xiv. of the _Veterinary Record_,
p. 716:
'An eighteen months' old filly showed a deformity of the third phalanx,
resulting in her walking with the front face of the hoof on the ground. The
flexors were apparently all right, and the bending back seemed to be due to
contraction of the ligaments of the joint and the sheath of the perforans.
'On the ground of absence of contraction of the flexors, or atrophy and
paralysis of the extensors, the surgeon considered the lesion curable by
simple orthopaedic measures. By means of an elongated toe-piece to the
shoe and calkins, which were shortened every fifteen days, the filly was
completely cured in seventy days.'
H. THE CROOKED FOOT.
(_a_) THE FOOT WITH UNEQUAL SIDES.
_Definition_.--The foot thus affected has one side of the wall higher than
the other.
_Symptoms_.--This deformity is the better recognised when the foot on the
floor is viewed from behind. In addition to the difference between the
height of the inner and outer heel is seen at once a deviation in the
normal direction of the horn. That of the higher side is distinctly more
upright than that of the lower, and runs from above downwards and inwards
towards the axis of the foot, while the horn of the lower side maintains
its normal direction of downwards and outwards.
From what we have said before on contracted foot, this bending in of
the wall of the upright side will at once be recognised as a form of
contraction. It is, in fact, contraction confined to one-half of the foot
only, and, as a result, the upright side of the crooked foot is prone to
the troubles arising from that condition. Corns are frequent, and atrophy
of that half of the frog on the affected side supervenes. With the
inflammatory changes accompanying these conditions we find the horn of the
affected side deteriorating in quality. It becomes dry and brittle, and
extremely liable to sand-crack. At the same time, thrush of the contracted
frog begins to make its appearance.
_Causes_.--More often than not this condition is a result of the
conformation of the limb. According as the build above inclines the animal
to 'turned in' or 'turned out' toes, so shall we have feet with a wall
crooked inwards or crooked outwards; and it may be mentioned here that the
evil results inflicted on the foot by ill-shaped limbs above will make
themselves the more readily noticed when the animal comes to be shod for
any length of time. So long as a natural wear of the foot is allowed,
so long does it accommodate itself to the form of limb above. So soon,
however, as the shoe is applied, and a more or less equal (and in this case
harmful) wear by that means insisted on, so soon does this abnormal change
in the height and direction of the horn fibres begin to make itself seen.
While arising in the majority of instances from faulty conformation of the
limb, crooked feet may also be brought about by bad shoeing, or by unequal
paring of the foot, and, in a few cases, from unequal wear of the foot in a
state of nature.
_Treatment_.--Although it may be taken as a rule that lowering of the
higher wall, even if persisted in at every shoeing, will do nothing towards
remedying the primary cause (viz., the evil conformation of the limb), yet
it will serve to keep the condition within reasonable limits. In this case,
while removing so much of the wall as is deemed necessary, care must be
taken to leave uncut the sole and the bar. Leaving these intact gives us
two natural and very potent protections against the contraction already
mentioned as impending.
Where, by reason of the thinness of the horn or other causes, sufficient
paring to equalize the tread cannot be practised, then the same end may be
arrived at by the use of special shoes. That branch of the shoe applied to
the half of the foot with the lower wall should be thickened from above
downwards. Or, on the same branch, may be turned up a calkin of sufficient
height for the purpose. Of the two methods the first is preferable.
In any case, whether depending upon paring, or upon the use of a special
shoe, the animal should be sent to the forge quite often, for it is only by
a well-directed, and therefore constant, application of the principles here
laid down that improvement may be brought about.
When marked contraction of one-half of the foot is present, it will be
best treated with the expanding shoe of Hartmann, already described in the
section of this chapter dealing with contracted heels (see Fig. 76).
(_b_) THE CURVED HOOF.
_Definition_.--The hoof with the wall of one side convex, and that of the
opposite side concave. Fig. 85, showing the foot in section from side to
side, gives an exact idea of this malformation.
_Causes_.--As was the case with the condition previously described, this
abnormality finds its primary cause in an unequal distribution of weight
due to vice of conformation in the limb above, causing one side of the
hoof to be higher than the other. As a result of this, the wall that is
inordinately increasing in height commences to bulge outwardly (Fig. 85,
_a_), while the opposite (Fig. 85, _b_) becomes concave.
The same state of affairs may be occasioned in the forge by leaving one
side of the foot too high, and subjecting the other to excessive paring for
several consecutive shoeings.
_Treatment_.--In the main this condition may be regarded as a long-standing
and aggravated form of the foot with unequal sides. We may say at once,
therefore, that it is not so easily remedied as that simpler defect; that,
although identical principles will be followed in its treatment, cure must
be a matter of some considerable time.
[Illustration: FIG. 85.--SECTION THROUGH A CROOKED FOOT. _a_, The higher
and convex side of the wall; _b_, the lower and concave side of the wall]
Again, we must look to successive parings of the wall of the higher side to
bring about a gradual return to the normal. At the same time, the tendency
to contraction of that side is counteracted by shoeing wide, and, if
necessary, giving to the upper surface of that branch of the shoe what we
have termed elsewhere a 'reversed seating'--viz., an incline of its upper
surface from within outwards.
CHAPTER VII
DISEASES ARISING FROM FAULTY CONFORMATION
A. SAND-CRACK.
_Definition_.--A solution of continuity of the horn of the foot, occurring
usually in the wall, and following the direction of the horn fibres.
_Classification_.--It is usual to classify sand-cracks according to--
_(a) Their Position_.--_Toe-crack_ when occurring in the middle line of the
horn of the toe, and _quarter-crack_ when occurring in the horn of the
quarters.
Sand-crack of the frog and sand-crack of the sole may also each be met
with. They are, however, of rare occurrence, and are seldom serious enough
to merit special attention.
The toe-crack is met with more often in the hind-foot than in the fore,
while the quarter-crack more often than not makes its appearance in the
fore-foot, and is there, as a rule, confined to the inner side. The reasons
for these positions being so affected we shall deal with when treating of
the causes of sand-crack in general. It is interesting to note that the
portions of wall known as inside and outside toe are seldom affected.
_(b) Their Length_.--_Complete_ when they extend from the coronary margin
of the wall to its wearing edge; _Incomplete_ when not so extensive.
_(c) Their Severity_.--_Simple_ when they occur in the horn only, and do
not implicate the sensitive structures beneath; _Complicated_ when
deep enough to allow of laceration and subsequent inflammation of
the keratogenous membrane. Such complications may vary from a simple
inflammation set up by laceration and irritation of the sensitive
structures by particles of dirt and grit that have gained entrance through
the crack, to other and more serious changes in the shape of the formation
of pus, haemorrhage from the laminal vessels, caries of the os pedis, or the
development of a tumour-like growth of horn on the inner surface of the
wall known as a keraphyllocele.
_(d) Their Duration_.--_Recent_ when newly formed; _old_ when of long
standing.
_(e) Their Starting-point_.--This last distinction we make ourselves,
and, referring to cracks of the wall, term them _high_ when commencing from
the coronary margin, _low_ when starting from the bearing surface.
_Causes_.--We have already classified sand-crack as a disease arising from
faulty conformation. Thus, in just so far as a predisposing build of body
may be handed down from parent to offspring, we may regard sand-crack as
hereditary. If we do so, however, we must afterwards make up our minds
to sharply distinguish between the sand-crack plainly brought about by
accidental cause, and that occurring as a result of hereditary evil
conformation.
With regard to the latter, we need hardly say that feet with abnormally
brittle horn are extremely liable. But with this, as with many other
affections of the feet, we shall find it necessary to consider several
causes acting in cooperation. In this case, for instance, given the brittle
horn, it becomes necessary to further look for exciting causes of its
fracture.
We will take conformation first. In the animal with turned-out toes a more
than fair share of the body-weight is imposed on the horn of the inner
quarter. Here, then, three causes exert their influence together: The horn
is brittle; the wall of the inner quarter is thinner than that of the
outer; additional weight is imposed upon it. Fracture results.
Take, again, the vice of contracted heels. Here, in the first place, we
have a variety of causes tending to bring about the contraction. With the
contraction, and its consequent pressure upon the sensitive structures
in the region of the quarters and the frog, has arisen a low type of
inflammation. The horn of the part has become dry and brittle. The exciting
cause of its fracture is found in an excessive day's work upon a hard, dry
road, with, perhaps, a suddenly-imposed improper distribution of weight,
due to treading upon a loose stone, or a succession of such evil transfers
of weight due to travelling upon a road that is rough in its whole extent.
In their turn, too, such defects of the feet as we have mentioned in the
last chapter--as, for example, the foot with the pumiced horn, the foot
with abnormally upright heels, or that which is upright on one side only,
or crooked--each offers a condition which is predisposing to the formation
of a sand-crack. In each case it wants but the uneven distribution of
the body-weight, which, as a matter of fact, some of these conditions
themselves give, to bring about a fracture.
Apart from the predisposition conferred by conformation, must be remembered
the simpler predisposing causes leading to brittleness of the hoof. We
refer to the after-effects of poulticing, the moving from pasture to
stable, the emigration from a damp to a dry climate, or the alternate
changes from damp to dry in a temperate region. Each may have a
deteriorating influence upon the horn, rendering it liable to the condition
we are describing. Excessive dampness alone, especially when the animal is
called upon to labour at the drawing of heavy loads upon a rough road, is
not infrequently a cause. In this case the wet, together with the constant
friction of the sharp materials of which the road is made, serves to
destroy the varnish-like periople. The wet gains access to the inner
structures of the wall, the agglutination of the horn fibres is weakened,
and fissures begin to appear.
Other causes of sand-crack are purely accidental. An animal at fast work
over-reaches. The secretion of horn at the injured coronet is interfered
with, a diminished supply at an isolated spot being the result. From this
point grows down a fissure in the wall.
An injury of the same character may also be sustained in various other
ways--treads from other animals when working in pairs, accidental wounding
with the stable-fork, blows of any kind, or a self-inflicted tread with the
calkin of an opposite foot--each with the same result.
So far as causation is concerned, toe-crack stands in a class almost by
itself. It is met with nearly always in a heavy animal in the hind-foot,
and is directly attributable to the force exerted in starting a heavy load.
Unskilful shoeing also plays a part in the causation of sand-crack. Removal
of the periople by excessive rasping of the wall is most certainly a
predisposing cause. Cracks, or their starting-points, may also be caused by
using too wide a shoe, or by the use of nails too large in the shank. Also,
they may arise from unskilful fitting of the toe-clip, especially in the
hind-foot of a heavy animal. It must be admitted, however, that the part
shoeing plays in the causation of sand-crack is not a large one; far more
depends upon the state of the horn and the animal's conformation than upon
the exciting cause.
So far, our observations on the causes of sand-crack have referred to that
form occurring in the wall. Sand-crack of the sole or frog we have already
said is but seldom met with, and then it is always in connection with some
exceptionally deteriorated quality of the horn, as in the case of badly
pumiced feet, or occurs as a result of direct injury. Extensive slit-like
cuts in this region, when deep enough to lacerate the keratogenous
membrane, are sometimes followed by the growth of a fissure in the horn,
and what might almost be termed a permanent sand-crack results. Such cuts
may be occasioned by sharp flints, broken glass, or other sharp objects
picked up on the road, or may result from the animal treading on the
toe-clip of a partially cast shoe.
_Symptoms_.--In every case the fissure, or evidence of its commencement,
is a diagnostic symptom. It is well to remember, however, that this may
be easily overlooked, especially when the crack is one commencing at the
coronary margin. The reason is this: Sand-cracks in this position often
commence in the wall proper, and not in the periople. They may, in fact, be
first observed as a fine separation of the horn fibres immediately
beneath the perioplic covering. A crack of this description may even show
haemorrhage, and have been in existence for some time, without the periople
itself showing any lesion whatever. Thus, unless lameness is present, or a
more than specially keen search is directed to the parts in question, the
sand-crack goes undiscovered, until of greater dimensions.
Further, the fissure may be hidden, either accidentally or of set purpose.
It may be covered by the hair, filled in and covered over with mud, or
intentionally concealed by being 'stopped' with an artificial horn, with
wax, or with gutta-percha, or, as is more common, be hidden by the lavish
application of a greasy hoof-dressing.
In this latter connection it is well to warn the veterinary surgeon,
especially the beginner, when examining for soundness, to be keenly
critical before passing an animal who is presented with feet smothered with
tar and grease or any other dressing. More especially should this warning
be heeded when examining any of the heavier breeds of animal with an
abundance of hair about the coronet.
Referring again to the search for the crack, it is well to know that with
toe-crack the fissure is the more readily seen when the foot is lifted from
the ground. With quarter-crack, on the other hand, the fissure is wider,
and consequently the easier detected with the foot bearing weight.
Although commencing in the insidious manner we have described, the lesion
is not thus often seen by the veterinary surgeon. Usually, the animal with
sand-crack is brought for his inspection when lameness has arisen from it.
In this case the cause for the lameness will reveal itself in the crack,
which is now too large to escape observation. The coronet is hot and tender
to the touch, and a sensation of warmth is sometimes conveyed to the hand
by the horn of the surrounding parts of the wall. It is hardly necessary to
say that, with accompanying conditions such as these, the sand-crack is a
_deep_ one.
Where the lameness is but slight, we may attribute it almost solely to the
pain occasioned by the mere wounding of the keratogenous membrane, and to
no very extensive inflammatory changes therein. By some authorities this
is said to be due to the pinching of the sensitive structures between
the edges of the fissure in the horny covering. In our opinion, however,
pinching does not occur unless inflammatory exudation into the sensitive
structures adjoining the crack has led to sufficient swelling to cause them
to protrude. In other words, the movements of the horny box, communicating
themselves to the structures beneath, and so occasioning movement in the
wounded keratogenous membrane, are quite sufficient to give rise to the
lameness without actual pinching of the structures implicated.
The severity of the lameness will vary with the rapidity of the gait, and
with the character of the road upon which the animal is made to travel. For
instance, many animals in which the lameness is imperceptible at a walk
become 'dead' lame at a fast trot. It is sufficiently explained when
one remembers the greater movements of expansion and contraction of the
posterior parts of the wall brought about by the increase in the rate of
progression. The same animal, too, will go distinctly more lame upon a hard
than upon a soft surface.
In like manner the lameness from toe-crack also varies in degree with the
rate of progression and the character of the travelling, though not to
such a noticeable extent as in the lameness from quarter-crack. A greater
variation may in this case be brought about by moving the animal on
ascending and descending ground. Descending an incline, with a more than
ordinary share of the body-weight thus thrown upon the heels, the lameness
is most marked. The reason would appear to be that the greater expansion
of the wall of the heels thus brought about leads to a proportionate
contraction of the wall at the toe, especially at the edges of the crack,
thus causing undue pressure upon the exact spot of the wound in the
sensitive structures. Ascending--the weight in this case transferred from
the posterior to the anterior portion of the foot--the expansion of
the heels becomes a contraction, with a corresponding lessening of the
contraction at the toe and a distinct decrease in the lameness.
In the case of a deep but recent crack there is always more or less
haemorrhage. This favours risk of infection of the lesion with pus-forming
organisms, and so leads to a more or less pronounced lameness, a degree of
swelling, heat and tenderness in the coronet above, and a certain amount of
surgical fever.
The acute symptoms subdued, but the fissure still remaining, gives us the
crack we have classified as 'old.' This may in every case be distinguished
from a more recent lesion by the amount of thickening of the overhanging
coronet, and the presence of an increased quantity of sub-coronary horn in
the region immediately about the crack. The previous inflammatory changes
in the adjoining sensitive structures have here led to an increased
secretion of horn, and a greater or less deposition of inflammatory
connective tissue in the wounded coronary cushion.
Sand-crack of the toe always follows the direction of the horn fibres. That
of the quarter, however, may on occasion run a course that is somewhat
zigzag, first following the direction of the horn fibres for a short
distance, then travelling in a horizontal direction, and finally continuing
its course again in a line with the horn fibres, commonly at a point
posterior to that at which it commenced.
In a quarter-crack that is old, and when contraction of the heels exists
(which in this case it usually does), then will often be found overlapping
of the edges of the crack. The expansion of the wall brought about when the
body-weight is on the heels, cannot, by reason of the break in it, continue
itself anterior to the crack. As a consequence, repeated expansion of the
wall posterior to the crack, with the portions anterior to it in a state
of enforced quiescence, leads in time to the posterior edge of the crack
coming to lie over that of the anterior.
_Complications_.--The first complication likely to arise in a case of
sand-crack is that attending simple laceration of the sensitive structures
in a _deep_ lesion. With the laceration all the phenomena of a repairing
inflammation make their appearance. As a result, there is more or less heat
according to the degree of inflammatory hyperaemia, swelling according to
the amount of inflammatory exudate, and pain according to the amount of
pressure the two foregoing bring to bear on the nerves in the inflamed
area.
A second and more serious complication is the greater inflammation set up
by the introduction into the crack of foreign substances. Small portions of
gravel and flint, both by the irritation set up by their friction and by
the infection they carry in with the dirt surrounding them, are responsible
for the mischief.
When, from direct communication with the blood-stream, due to extensive
haemorrhage, bacteria from the outside gain entrance, this simple
inflammation is further complicated by the formation of pus, or a limited
gangrene of the keratogenous membrane.
In cases of great severity the gangrene of the keratogenous membrane
spreads until the deeper structures are involved. We then get a necrosis
(in the case of toe-crack) of the extensor pedis, and sometimes caries of
the os pedis.
In like manner the necrotic changes occurring under these circumstances may
invade the deeper structures in the region of quarter-crack. As a result of
this, we may have the starting-point of suppurating corn, or necrosis of
the lateral cartilage--in other words, cartilaginous quittor.
Commonly accompanying quarter-crack is the condition of contracted heels
and atrophied frog. Sometimes described as a complication of sand-crack, it
appears to us more rational to rather regard the sand-crack as a result or
complication of the vice of contraction.
The overlapping of the edges of the crack before referred to occasionally
gives rise to the condition known as false quittor. A probe or a director
passed beneath the overhanging ledge of horn reveals sometimes a fissure of
1 inch or considerably more in depth, and quittor is diagnosed. A careful
paring away of the overhanging horn, however, reveals the true state of
affairs, and exposes to view the original cause of the mischief--a simple
fissure in the wall.
A serious complication--one fortunately met with but rarely--is that of
keraphyllocele. This is a tumour-like growth of horn, varying in size from
the thickness of an ordinary quill pen to that of one's middle finger,
growing down from the coronary cushion, and attached to the inner side of
the wall of the hoof. With this lameness is always present, and more or
less deformity of the hoof results. This condition will be found described
at greater length in Chapter IX.
_Prognosis_.--In the case of sand-crack this should always be guarded. It
may be taken as a general rule that cracks commencing from the coronary
margin are more troublesome to deal with than those originating below. The
reason is not far to seek. They here affect the wall just where the bevel
in it for the accommodation of the coronary cushion has rendered it
weakest. Not only is it weakest, but being more resilient than the portions
below it, it suffers more from the alternate movements of expansion and
contraction of the foot than does the horn below.
Although in many cases a cure of the existing crack may be easily
accomplished, regard should be paid to the possibility of its recurrence,
either in the same position or elsewhere. Really, in offering an opinion
as to the future usefulness of an animal so affected, a greater attention
should be directed to the animal's conformation than to the crack itself.
Where the vice of conformation giving rise to it (as, for example,
contracted heels or upright hoof) gives hope of being remedied, then
naturally it may be safely said that the liability to sand-crack goes with
it.
A like favourable prognosis may be given in the case of cracks occasioned
by purely accidental causes.
Ordinarily, however, cracks once commenced tend rather to increase than
decrease in size and severity. From being superficial and incomplete, they
become complete and deep, with every unfavourable circumstance that an
increase in size and depth brings with it.
This much, however, may be promised to the owner. A simple crack, even
though originating from the coronary margin, is, in the vast majority of
cases, curable. Under a rational treatment its increase in size may be
prevented, and a sound wall caused to grow down from the coronet.
_Treatment_.--The principles governing the treatment of sand-crack are
simple enough in themselves, if not always followed by success.
1. _Preventive_.
This, as a rule, does not suggest itself until a crack of greater or less
extent has made its appearance. Then, simultaneously with the treatment
proper of the lesion, preventive measures should be adopted, to aid both in
the healing of the fissure already present, and to ward off the occurrence
of others that might be likely to form. The hoof, if abnormally brittle,
should be regularly dressed with a suitable ointment (one containing
glycerine for preference), and its horn kept as nearly as possible in
a normal condition. When the condition of the horn predisposing to its
fracture is brought about by excessive wet, then the appropriate preventive
measures to be adopted suggest themselves.
With regard to the lesion itself, we may term 'preventive treatment' all
those measures having for their object the prevention of increase in the
size of the crack. They are as follows:
_(a) Blistering the Coronet_.--In a simple case, where the crack is
superficial and close under the coronary margin of the wall, a sharp
cantharides blister to the coronet immediately above it will have the
desired effect. An increased secretion of horn is brought about, and by
this simple means the crack prevented from becoming longer. Very often this
is all that is necessary. In fact, we may say here that, no matter what
other treatment is adopted, the simultaneous application of a blister to
the coronet is always beneficial. To derive full advantages therefrom,
the blistering should be repeated several times at intervals of about a
fortnight.
_(b) Clamping the Crack_.--When the services of a skilled smith are at
hand, one of the readiest methods of performing this is to draw the edges
of the crack together with an ordinary horse-nail.
On each side of the crack a small horizontal furrow is burned or cut into
the wall, leaving the horn for about 1/4 inch on each side of the crack
intact. This provides a groove for the ends of the clamping-nail to rest
in, and brings them flush with the outer surface of the wall. The nail is
then driven carefully home through the crack, and the pointed end grasped
by the farrier's pincers. The edges of the crack are then drawn tightly
together, and the nail firmly clenched.
[Illustration: FIG. 86.--THE SAND-CRACK FIRING-IRON.]
'The horse-nails are prepared in the ordinary way as for driving, with the
exception that each is pointed on the reverse side, to prevent puncturing
the sensitive structures. Before being used the nails are put in a vice,
and the head hammered to form a shoulder, to prevent their being driven too
far into the wall, and breaking out the hold.'[A]
[Footnote A: _Veterinarian_, vol. xlviii., p. 100.]
Before driving the nail some operators burn or bore a hole for it. Opinion
seems to differ as to whether this is at all necessary.
A method of clamping which, on account of its simplicity, has become
greatly popular, is that of Vachette. For this operation is needed the
outfit depicted in Figs. 86 and 87.
[Illustration: FIG. 87.--THE SAND-CRACK FORCEPS AND CLAMP.]
With the special firing-iron (Fig. 86) an indentation, sufficiently large
to admit the points of the clamp (Fig. 87), is made on each side of the
crack. The clamp is then adjusted, and pressed home tight by means of the
sand-crack forceps (Fig. 87). According to the length of the crack, one,
two, or three clamps may be necessary. Another useful clamp, though far
more complicated in its structure, is that of Professor McGill (Fig. 88).
[Illustration: FIG. 88.--MCGILL's SAND-CRACK CLAMP.]
'The object of this invention is to arrange on a spindle, which is
screw-threaded at one end with a right-hand thread and at the other with a
left-hand thread, two clips or clamps, free to travel on the thread, there
being a nut between the two which can be turned by a spanner. The clips
are placed on the hoof, one on each side of the sand-crack, the hoof being
prepared to receive the instrument by filing a groove or notch for the
clamps to fit into, and by turning the nut on the screw the clamps
are brought towards each other, and the crack thus prevented from
spreading.'[A]
[Footnote A: _Veterinarian_, vol. lxi., p. 141.]
Still a further useful clamp is that of Koster. This is considerably
broader than the clamp of Vachette, and its gripping edges are provided
with teeth (see Fig. 89).
As with the clamp of Vachette so with this, a groove is burned into the
wall on each side of the crack for the accommodation of the jaws of the
instrument, and the clamp itself pressed home by means of a special pair of
forceps. This form of clamp holds well, and has the advantage of securing a
wider area of horn than that of Vachette or McGill.
[Illustration: FIG. 89.--KOSTER'S SAND-CRACK CLAMP.]
Clamping by any method should be advised or undertaken only under certain
conditions. The horn should be moderately strong, and the wall should be
thick. This practically restricts the use of the clamp to cracks of the
toe, and it is there, as a fact, they are found of most benefit. While
burning the grooves for the clamp, and while tightening the clamp itself,
the animal's foot should be on the ground and bearing weight at the heels,
thus insuring the greatest possible approximation of the edges of the
crack.
With all methods of clamping an untoward result is sometimes the formation
of a fresh crack at the point of insertion of the clamps.
(c) _By the Use of Thin Metal Plates_.--These are of use when the horn of
the wall is too thin to allow of clamping, and are therefore of especial
use in cracks of the quarters. The plates are made so as to cover the
greater part of the length of the lesion, and are fastened to the wall
by two or more screws on either side of the crack. It is an advantage to
slightly let the plate into the wall by means of fitting it hot. In a
complicated crack the plate serves the further useful purpose of holding in
position antiseptic pledgets, and so keeping the lesion free from dirt and
grit.
_(d) By Various Methods of bandaging the whole Circumference of the
Wall_.--In our opinion this method of attempting to secure immobility of
the crack, and so prevent its extension, is not often followed by success.
The main objection to the method is that it subjects the whole of the wall
to the same pressure, and does not restrict the operation to the point at
which it is required. As in the case of the metal plate, however, this
method has the advantage that antiseptic dressings may be kept in position
in the case of a complicated crack.
[Illustration: FIG. 90.--SAND-CRACK BELT.]
The binding of the wall may be accomplished in two ways. The simpler of the
two is to merely apply the sand-crack belt depicted in Fig. 90. Beneath
this should be applied a compress of tar and tow or other material, and the
whole tightened up and kept in position by means of the buckle and strap.
This method of binding admits of after-tightening should it unfortunately
work loose.
The older method of binding the wall, and one now often practised by the
smith, is to use a quantity of so-called 'tar-band' or other stout cord.
With this the foot is neatly bound after the manner of a cricket-bat
handle, and all movement of the crack apparently restricted. There is
always a tendency, however, for such a dressing to work loose, and in the
case of a complicated crack it has the disadvantage of permanently hiding
from view the changes taking place in the discharge from the fissure.
_(e) By wedging the Crack_.--This is the exact opposite of clamping.
Whereas in clamping we obtain immobility of the crack by keeping it fixed
in the position of greatest approximation of its edges, in wedging, the
crack is rendered free from movement by maintaining it in that position
where its edges are most widely separated. In this case the edges of the
crack are pared smooth, the cavity thoroughly cleansed, and a wedge of hard
wood firmly driven in so as to fit exactly the fissure.
On the face of it it appears that this procedure would really tend to force
open and so lengthen the crack, especially at its coronary extremity. What
one should really remember, however, is that the crack _is not made wider_
than before, but that it is simply maintained in a position occurring with
every contraction of the heels of the foot, when it is normally at
its widest. Movement of the edges is thereby stopped, the immediately
surrounding structures are rested, and a new growth of horn, free from
crack, induced to grow down from the coronet.
This method of treatment only serves to emphasize the fact that, with a
sand-crack once formed, it is the constant movement of the parts that tends
most to keep it in existence, and not any particularly marked exertion of
force.
Some practitioners, with the wedge, apply also a clamp, thus assuring
additional firmness and solidity to that portion of the wall under
treatment.
The method of wedging is undoubtedly successful, if neatly performed.
_(f) By Surgical Shoeing_.--A partial rest is given to the affected parts
by easing the bearing of the shoe at the point required. This may be done
either by removal of part of the wall at the spot indicated, or by thinning
the web of the shoe in the same position. The former is the method usually
practised. Cessation of movement given in this way is, as we have already
said, only partial; for, while the effects of pressure and concussion from
below are minimized, the crack is still able to suffer from the movements
of expansion and contraction of the foot. Still, as an auxiliary to other
treatments, 'easing' of the wall under the affected part should always be
practised.
[Illustration: FIG. 91.---THE BEARING 'EASED' BY REMOVAL OF THE WALL.]
[Illustration: FIG. 92.--THE BEARING 'EASED' BY THINNING THE WEB OF THE
SHOE.]
Figs. 91 and 92 show respectively the manner of 'easing' by removal of
the wall, and by thinning the web of the shoe. In this connection it is
necessary to point out that on no account should 'springing' of the heels
of the shoe be allowed. Fig. 93 illustrates the ill-practice.
In this case, when the entire weight is thrown on to the heels, the portion
of wall posterior to the crack is bound to participate unduly in the
downward movement, and so tend to widening of the crack at its highest
point.
[Illustration: FIG. 93.--THE BEARING 'EASED' BY 'SPRINGING' THE HEEL OF THE
SHOE.]
We have already referred to the matter of 'clips.' In no case, whether the
crack be at the toe or in the quarters, should a clip be placed immediately
below it. If the crack is at the toe, the usual clip should be dispensed
with, and a clip at each side made to take its place. At the same time care
should be taken to avoid throwing the weight far forward. For that reason
a shoe with calkins or with very high heels should be removed, and a shoe
with an ordinary flat web substituted.
In the case of quarter-crack, where the constant movement of the parts
under expansion and contraction of the foot makes itself most felt, it is
wise to apply a shoe with clips fitting moderately tight against the
inside of the bars. By this means movement will to a very large extent be
curtailed.
Where a marked tendency to contraction is found, as is often the case with
quarter-crack, then the shoe with the clips may be rendered more marked in
its operation by giving to the outer face of each clip--that face applied
to the bar--a slope from above downwards and outwards. In other words, a
slipper shoe should be applied and the contraction given equally as much
attention as the sand-crack itself.
Where the crack is situated far back in the quarter, and easing of the
bearing cannot be accomplished without tending to spring the heels, then
the most suitable shoe is a bar shoe. With it the bearing may, of course,
be eased in exactly the position required, and the heels still allowed
to take their fair share in bearing the body-weight, and thus assist in
closing the crack. The bar shoe, if properly fitted, gives us also a
bearing on the frog, and aids greatly in counteracting contraction.
2. _Curative_.
_(a) The Application of Dressings to the Lesion_.--In the case of a recent
crack, deep, and attended with haemorrhage, the foot should be thoroughly
cleansed. Where possible, a constant flow of cold water from a hose-pipe
should be allowed to run over the foot. By this means the inflammatory
symptoms will be held in check and pain prevented. Later the shoe may be
eased at the required place, and a blister applied to the coronet. This,
with rest, will sometimes prove all that is needed.
Should a crack be of old standing, and complicated by the presence of pus,
a course of hot poulticing will often prove of benefit. The poultice should
be medicated with any reliable disinfectant, and should be renewed, or at
any rate reheated, two or three times daily. The crack itself should be
thoroughly cleaned after the removal of each poultice, and a concentrated
antiseptic solution--such as Tuson's spts. hydrarg. perchlor., carbolic
acid, and water, (1 in 10) or liquor zinci chlor.--poured into it. On
discontinuing the poulticing, the strength of the antiseptic solutions may
be decreased, the parts rested by correct shoeing, and a blister applied to
the coronet as before.
If these measures alone should prove insufficient, then the surgeon will
either fall back on those we have just related, or proceed to methods next
to be described.
_(b) Immobilizing the Crack by Means of grooving the Wall_.--To our
minds, this is as ready and withal as successful a method of dealing with
sand-crack as has yet been devised. It may be done in a variety of ways:
(1) By two grooves arranged about the crack in the form of a V, as Fig. 94;
(2) by a perpendicular groove on either side of the crack, about 1 inch in
distance from it, and parallel with the horn fibres, as Fig. 95; (3) by a
single horizontal groove at the extreme upper limit of the crack; (4) by
drawing two horizontal grooves, one at its upper and one at its lower end
(see Fig. 96).
[Illustration: FIG. 94, FIG. 95, FIG. 96. In Figs. 94, 95, and 96 the thick
black lines illustrate the positions of the various grooves made with the
firing-iron for the purpose of immobilizing a quarter sand-crack.]
The points to be observed in carrying out this line of treatment are simple
enough. In all cases see that the crack is rendered as clean as possible
by the use of suitable dressings, and if an excess of horn is present
immediately around it, as in the case of a long-standing and complicated
lesion, have it thinned down by rasping.
All that is then needed is one or two moderately sharp, flat firing-irons.
The groove is then burned into the horn in the positions indicated, and
that portion of the wall containing the sand-crack thus prevented from
participating in the movements of the foot. For our own part, we consider
the V-shaped incision, or either of the horizontal methods of grooving,
preferable to lines running in the direction of the horn fibres. With the
latter there is certainly a greater tendency to the formation of new cracks
than with either of those we advocate. The V-shaped incision we consider
most suitable of all, for the reason that by its means a greater degree of
immobility is conferred upon the necessary portion of the wall.
Whichever method is adopted, care should be taken to carry the grooves deep
enough into the horn, taking them down as near as possible to the sensitive
structures. At the same time, especial care should be exercised in not
carrying them too deep at their extreme upper limit, or in that case the
liability to the formation of fresh cracks in those positions will be
greatly increased.
After grooving, a sharp blister should be applied to the coronet every
three or four weeks, and the animal, if free from lameness, put to work.
_(c) By stripping away a V-shaped Portion of the Wall around the
Crack_.--This method is only indicated when the crack is greatly
complicated by the presence of pus, or by the growth of adventitious horn
on the inner surface of the wall. A radical cure is thus obtained, but the
animal for a longer time incapacitated from work.
The operation is best performed by first grooving a line to connect the
points _a_ and _c_ (Fig. 97). This should run immediately under the
coronary margin of the wall, and should stop short of injuring the coronary
cushion beneath. Grooves forming the sides _ab_ and _bc_ of the triangular
piece of horn are next made, and the horn contained within the lines _ab,
bc_, and _ca_, carefully removed. The grooves are the easiest made by a
cautious use of the firing-iron. The greater thickness of the horn may
thus be penetrated, and the grooves afterwards carried to their full and
requisite depth by the use of the drawing-knife.
With the removal of the horn the diseased structures are exposed to view.
All such should be removed by a free use of the scalpel, and a suitable
dressing afterwards applied. A necessary factor in the treatment is the
employment of pledgets of antiseptic tow. With these the exposed tissues
are covered, and the successive turns of a bandage run tightly over
them, so as to exert a moderate degree of pressure. When haemorrhage has
accompanied the operation, this dressing should be removed on the following
day, the wound dressed, and the pledgets of tow and the bandage renewed.
Any after-dressing need only then be practised at intervals of a week.
Repair after this operation is rapid, and takes place both from the exposed
podophyllus membrane and from the coronary cushion.
[Illustration: FIG. 97. The dotted lines outline the V-shaped portion of
wall to be removed in the treatment of complicated toe-crack.]
[Illustration: Fig. 98. The dotted lines indicate the portion of wall to be
removed in the complete operation for complicated toe-crack.]
_(d) By stripping the Wall from the Coronary Margin to its wearing Edge on
Either Side of the Crack_.--This is merely a more extensive application
of the method just described, and is only indicated in a _complete_ and
_complicated_ crack that has refused to yield to other modes of treatment
(see Fig. 98).
As in the previous case, a groove is run from _a_ to _c_. The grooves _ab_
and _de_ are then continued to the lowermost edge of the wall, and the
whole of the wall within these points removed. To facilitate removal,
the white line should be grooved between the points _b_ and _d_.
After-treatment is exactly the same as that just referred to.
B. CORNS.
_Definition_.--In veterinary surgery the term 'corn' is used to indicate
the changes following upon a bruise to that portion of the sensitive sole
between the wall and the bar. Usually they occur in the fore-feet, and are
there found more often in the inner than in the outer heel.
The changes are those depending upon the amount of haemorrhage and the
accompanying inflammatory phenomena occasioned by the injury.
Thus, with the haemorrhage we get ecchymosis, and consequent red staining
of the surrounding structures. As is the case with extravasations of blood
elsewhere, the haemoglobin of the escaped corpuscles later undergoes a
series of changes, giving rise to a succession of brown, blue, greenish and
yellowish coloration.
With the inflammation thereby set up we get swelling of the surrounding
bloodvessels, pain from the compression of the swollen structures within
the non-yielding hoof, and moistness as a result of the inflammatory
exudate.
In a severe case the inflammation is complicated by the presence of pus.
_Classification_.--Putting on one side the classification of Lafosse
_(natural_ and _accidental_), as perhaps wanting in correctness, seeing
that all are accidental, and disregarding the suggested divisions of Zundel
_(corn_ of the _sole_ and _corn_ of the _wall_) as serving no practical
use, we believe, with Girard, that it is better to classify corns according
to the changes just described.
Following his system, we shall recognise three forms: (1) _Dry_, (2)
_moist_, (3) _suppurating_.
The _dry_ corn is one in which the injury has fortunately been unattended
with excessive inflammatory changes, and where nothing but the coloration
imparted to the horn by the extravasated blood remains to indicate what has
happened.
The _moist_ corn is that in which a great amount of inflammatory exudate is
the most prominent symptom. It indicates an injury of comparatively recent
infliction.
The _suppurating_ corn, as the name indicates, is a corn in which the
inflammatory changes are complicated by the presence of pus.
_Causes_.--The causes of corns we may consider under two headings--namely,
_predisposing_ and _exciting_.
_Predisposing Causes_.--By the heading of this chapter we have already
intimated that corns are due to faulty conformation of the foot. It is,
therefore, merely a description of such shapes of foot as favour their
formation that will need mention here.
The wide, flat foot, with low heels, may be first considered. Here the
posterior portions of the sole, those portions between the wall and the
bars, fall very largely in the same plane as the wearing surface of the
bars and the wall. As a consequence, these portions of the sole are more
prone to receive injury from stones and rough roads and from the pressure
of the shoe.
The low heels, too, favour a more than due proportion of the body-weight
being thrown on to the posterior parts of the foot. Two evils, both
inclining to the production of corn, result from this. In the first
place, the sensitive structures of the posterior portions of the foot are
subjected to undue pressure from above; secondly, the posterior half of
the foot, by reason of the extra weight thrown upon it, is exposed also to
greater effects of concussion than normally it should meet. Added to this
we find that the abnormally flat condition of the sole has resulted in
a great loss of resiliency. With undue pressure above, and a loss of
resiliency and added effects of concussion below, the sensitive structures
included between the opposing pedal-bone and the horny sole are bound
to suffer more or less bruising each time the foot comes to the ground,
especially if the animal is moved at a rapid pace.
Writing here of the effects of pressure and concussion affords a fitting
occasion to mention the fact that corns occurring in feet affected with
side-bones are always worse than in feet with normal elastic cartilages.
The explanation of this is simple, for there can be no doubt that the
loss of resiliency in the diseased cartilage is only another aid to undue
pressure and concussion. The sensitive structures are pinched between
unyielding bone above and practically unyielding horn below.
Feet with high and contracted heels are also predisposed to corn. The
Back to Full Books
|