Lameness of the Horse Part 14

In chronic tendinitis there occurs repeated attacks of inflammation wherein lameness is p.r.o.nounced and there exists in reality, at such times, acute inflammation of a hypertrophic structure, where at no time does inflammation completely subside. Therefore, in chronic tendinitis there is to be found at times the same conditions which characterize acute inflammation, except that there is usually a variance of symptoms because of the difference in the degree of inflammation and pain.

The diagnosis of contraction of tendons is an easy matter because of the fact that relations between the phalanges are constantly changed with tendinous contraction. If one bears in mind the attachments and function of the digital flexors, no difficulty is encountered in recognizing contraction of either tendon.

Contraction of the superficial digital flexor (perforatus), when uncomplicated, is characterized by volar flexion of the pastern joint.

The foot is flat on the ground and the heel is not raised because the superficial flexor tendon does not have its insertion to the distal phalanx (os pedis) and therefore can not affect the position of the foot.

By causing the subject to stand on the affected member, one may outline the course of the flexor tendons by palpation, and in this way recognize any lack of tenseness or contraction of tendons or of the suspensory ligament.

[Ill.u.s.tration: Fig. 21--Contraction of the deep flexor tendon (perforans) of the right hind leg, due to tendinitis.]

Contraction of the suspensory ligament would cause the pastern joint to a.s.sume the same position as is occasioned by contraction of the superficial digital flexor (perforatus) tendon, but when the subject is bearing weight on the affected member, it is easy to determine that no contraction of the suspensory ligament exists, by noting an absence of abnormal tenseness of this structure. And finally, contraction of the suspensory ligament is of rare occurrence.

Contraction of the deep flexor tendon (perforans) causes an elevation of the heel. The foot can not set flat because the insertion of the deep flexor tendon to the solar surface of the distal phalanx (os pedis) causes when the tendon is contracted--a rotation of the distal phalanx on its transverse axis--hence the raised heel. No other tendon has this same effect on the distal phalanx and the condition is correctly diagnosed without difficulty.

[Ill.u.s.tration: Fig. 22--A chronic case of contraction of both flexor tendons of the phalanges. In this case (presented at a clinic of the Kansas City Veterinary College) because of long continued contraction of the flexors, which prevented weight being supported with any degree of comfort, there resulted a partial paralysis of the extensors, and consequently the extremity was dragged on the ground.]

Course and Complications.--This condition may exist for years without causing the subject any serious inconvenience, if the affected animal is kept at suitable work. In other instances recurrent attacks of lameness are of such frequent occurrence that the subject is not fit for service.

Many affected animals that are kept in service in spite of lameness (and in some instances where no lameness is present), soon become unserviceable because of contraction of the inflamed tendon. This, in fact, is the condition which eventually becomes established in most instances.

Treatment.--Where conformation is not too faulty so that recovery may be expected, good results are obtained by line-firing the tendons and allowing the subject a few months' rest. In some cases median neurectomy is advisable. This is recommended by Breton[25] as being productive of good results even where contraction of tendons exists and tenotomy is done.

[Ill.u.s.tration: Fig. 23--Contraction of the superficial and deep flexor tendons (perforatus and perforans) of the left fore leg.]

By shoeing with high heel-calks considerable strain is taken from the inflamed tendons because of the changed position of the foot which alters the distribution of weight on different parts of the leg. Rubber pads materially diminish concussion and should be made use of when the subject is returned to work, if the character of the work is such as to occasion much concussion.

It is to be remembered, however, that in sprains there occurs fibrillary fracture of soft structures and time is required for regeneration of tissue which has been injured or destroyed. Absolute rest is necessary where inflammation is acute and in sub-acute or chronic tendinitis avoidance of all work which causes irritation to the affected tendons is imperative.

[Ill.u.s.tration: Fig. 24--Contraction of superficial digital flexor and slight contraction of deep flexor tendon.]

Where contraction of tendons exists surgical treatment is necessary. No good comes from appliances which are calculated to stretch the affected tendons; in fact, they aggravate the inflamed condition and hasten complete loss of function of the affected member. Where there exists no articular or ligamentous diseases which would defeat the purpose, tenotomy is the only remedy for contracted tendons.

Contracted Tendons of Foals.

Etiology and Occurrence.--This condition is occasionally observed and no positive explanation of the reason for its existence can be given.

That mal-position _en utero_ causes the metacarpal bones to develop in length so rapidly that the tendons are too short, is an explanation that is offered. Be that as it may, in breeding sections of the country the general pract.i.tioner is obliged to handle these cases and successful methods of treatment are essential even though cause is not removable.

Symptomatology.--The superficial flexor tendon (perforatus) alone, is the one usually contracted, and while both flexors are at times involved, this rarely occurs. The condition is usually bilateral.

The degree of contraction varies greatly in different cases. In some, contraction exists to such extent that it is impossible for the colt to stand, and because of continual decubitus where no relief is given, the subject is lost because of gangrenous infection occasioned by bed sores.

Otherwise the same symptoms are to be observed in this condition, that exist in contraction of tendons of the mature animal.

Treatment.--Wherever contraction is not too marked and weight is borne with the affected members, and where the feet can be kept on the ground in a nearly normal position, it is possible to correct the condition without doing tenotomy. That is, in cases where the subject is simply "c.o.c.k-ankled", where volar flexion of the pastern joint exists but the foot is kept flat on the ground, correction is possible without tenotomy.

In such instances the foal must be treated early--before the skin on the anterior pastern region has been badly damaged by knuckling over. It is possible in many cases to stretch the flexor tendons by grasping the colt's foot with one hand, and with the other hand one may push the pastern in the direction of dorsal flexion. This may be tried and when a reasonable amount of force is employed, no harm is done, even though no material benefit results. Some veterinarians claim good results from this treatment alone and direct their clients to repeat the stretching process several times daily.

Whether the tendons are manually stretched or not, splints should be adjusted to the affected members. The legs are padded with cotton and bandages and a suitable splint is applied on either side of the members and securely fixed in position by bandaging.

The splints are kept in position for four or five days and then removed for inspection of the affected parts. If necessary, they are reapplied and left in position for a week; however, this is unnecessary in the average case that is treated in this manner.

Where contraction exists to the extent that the subject can not stand and where no weight is borne by the feet, it is necessary to divide the affected tendons surgically. The same technic is put into practice that is employed in the mature subject but there is much greater chance for a favorable outcome in the foal. Further, if necessary, one may divide with impunity, both tendons on each leg, at the same time. In all cases this operation is done by observing strict aseptic precautions and the legs are, of course, bandaged. If both tendons are divided, splints should be employed and kept in position for ten days or two weeks.

Primary union of the small surgical wound of the skin and fascia occurs in forty-eight hours.

The reader is referred to William's "Veterinary Surgical and Obstetrical Operations," for a complete description of this operation.

In veterinary literature there is occasionally described a condition which affects young foals wherein symptoms similar to those of contraction of the flexors are manifested, but upon examination it is found that rupture of the extensor of the digit (extensor pedis) exists. This affection is briefly described by Cadiot but no complete treatise on this condition has been published.

In parts of Canada foals of from one to three days of age are found affected in such manner that more or less interference with the gait is to be seen in those moderately affected. There is, in some subjects, only a slight impediment in locomotion which is occasioned by inability to properly extend the digit. In other subjects, while able to stand and walk, great difficulty is experienced because of volar flexion of the phalanges. The more seriously affected animals are unable to stand and, in most instances, perish because of the effects of prolonged decubitus.

A local enlargement occurs at the anterior carpal region and the ma.s.s is somewhat fluctuating, extravasated fluids becoming infected in many instances, and necrosis of the skin and fascia provide means for spontaneous discharge of the contents of the enlargement if it is not opened. The infection when it becomes generalized causes a fatal termination in most cases that are not treated.

[Ill.u.s.tration: Fig. 25--"Fish knees."--Photo by Thos. Millar, M.R.C.V.S.]

Native stock owners of some parts of Canada know this condition as "fish knees" because of the presence of the ruptured end of the extensor tendon which is found coiled in the cavity of the enlargements caused by the ruptured tendon.

Local pract.i.tioners have treated the condition by incising the swollen ma.s.s and removing the part of tendon contained within such cavities. Treatment has not proved entirely satisfactory in the majority of instances, perhaps because of tardy interference.

In a colt's leg sent the author by Mr. Thomas Millar, M.R.C.V.S., of Asquith, Saskatchewan, a careful dissection of the carpal region revealed the fact that in this case the ruptured extensor tendon was due to injury. The colt may have been trampled upon by its dam in such manner that the tendon was divided. No noticeable evidence of injury to the skin was to be seen on its outer surface, but on the fascial side a cyanotic congested area, which was situated immediately over the site of the ruptured tendon, was very evident.

With the execution of a good surgical technic, the ruptured tendon might be sutured; the wound of the tendon sheath as well as that of the skin carefully united by means of gut sutures, the leg bandaged and immobilized with leather splints and recovery follow in a reasonable percentage of cases so treated. These cases afford an opportunity for the perfection of practical means of treatment by those who frequently meet with this affection.

Rupture of the Flexor Tendons and Suspensory Ligament.

Etiology and Occurrence.--Rupture of the flexor tendons or of the suspensory ligament is of rare occurrence. Frequently, these structures are divided as the result of wounds; but rupture, due to strain, is not frequent.

[Ill.u.s.tration: Fig. 26--Extreme dorsal flexion said to have resulted from an attack of distemper. From Amer. J'n'l. Vet. Med., Vol. XI, No.

4.]

In some cases in running horses, or in animals that are put to strenuous performances, such as are jumpers, rupture of tendons or of the suspensory ligament takes place. However, more frequently this follows certain debilitating diseases such as influenza or local infectious inflammation of the parts which results in degenerative changes and rupture follows.

The non-elastic suspensory ligament receives some heavy strains during certain att.i.tudes which are taken by horses in hurdle jumping as is explained in detail by Montane and Bourdelle[26] under the description of this ligament. But in spite of the frequent and unusually heavy strains, which these structures receive, complete rupture is not frequently seen.

Symptomatology.--When the anatomy and function of the flexor tendons and suspensory ligament is thoroughly understood, recognition of rupture of either of these structures is easily recognized. When one considers that in rupture, a position directly opposite to that which is seen in contraction in either one of these structures, is a.s.sumed, a detailed description of each separate condition is needless repet.i.tion.

However, it is pertinent to suggest that rupture of the deep flexor tendon (perforans) allows a turning up of the toe. Whether it be torn loose from its point of attachment or ruptured at some point proximal thereto, the position is the same--heel flat on the ground, toe slightly raised and this raising of the toe varies in degree as the subject moves about.

When the superficial flexor (perforatus) is ruptured there is no change in the position of the foot but the fetlock joint is slightly lowered.

The pathognomonic symptom is the lax tendon during weight bearing, which may be felt by palpation of the tendon along its course in the metacarpal region.

With complete rupture of the suspensory ligament there occurs a marked dropping of the fetlock joint and an abnormal amount of weight is then thrown upon the superficial flexor tendon (perforatus), causing it to be markedly tensed. This is readily recognized by palpation. By palpating the suspensory ligament from its proximal portion down to and beyond its bifurcation, while the affected member is supporting weight, it is possible to diagnose rupture of one of its branches.

Prognosis and Treatment.--In rupture of the superficial flexor tendon (perforatus) because of its comparatively less important function, prognosis is favorable and recovery takes place when proper treatment is put into practice.

With rupture of the deep flexor tendon (perforans), especially when it occurs at or near its point of insertion and sometimes following disease, prognosis is unfavorable.

Rupture of the suspensory ligament const.i.tutes a condition which is, as a rule, hopeless, because of the impracticability of treating such cases.