Common Lameness Conditions in Horses Hind Limb

There are numerous conditions, which affect the hind limb of the horse and these vary according to breed, conformation, the type and intensity of activity as well as the surface upon which they are worked. However there are some conditions, which are seen on a more regular basis than others.

Bog Spavin

This condition is a soft swelling of the hock joint. The swelling is the result of an accumulation of fluid in the joint space. Poor hock conformation, trauma, and stressful exercise may contribute to susceptibility. The main part of the swelling is seen at the front of the joint to the inside of the limb. Sometimes two additional swellings are noted at the back on the sides of the hock joint; inside and out. Lameness does not always result, but the area may be tender at least in the initial phases. Advice should be sought from your veterinary surgeon as to whether they consider treatment to be necessary which in many cases it won’t.

Bone Spavin

This is an arthritic condition of the hock. Horses with cow hocks or sickle hocks are more commonly affected as are Standardbred horses. A bony swelling will be noted on the inside of the lower hock joint, and the horse will tend to wear the toe of the hoof. The swelling may not be apparent in the early phases and the first indication may be lameness.

Your veterinary surgeon will initially investigate a lameness isolated to the hock and they may take radiographs (X-rays). These will show changes in bone density within the hock joint. Treatment varies with the extent of the condition and may include box rest, intra-articular (joint) injections or even surgery.

In spite of numerous types of medical and surgical therapy, in the worst cases, this condition may result in permanent lameness. The prognosis (prediction of outcome) is always guarded and complete recovery is not always attainable but the horse may be able to perform normally to a low intensity of exercise. A period of stiffness until the animal has warmed up is to be expected.

Curb

This is a condition that produces a swelling along the back of the hind leg just below the hock. It is the result of damage to a ligament that helps stabilize the hock joint. The inflammation results in new bone production around the attachment of the ligament and results in a thickened appearance. These horses are sore for a period of time until the inflammation has settled. Sickle or cow hocks (poor conformation) and trauma predispose to the disease. The prognosis is more favorable if trauma is the inciting cause than if the condition results from poor leg structure.

Upward Fixation of the Patella

Horses have the ability to lock their stifle joint (knee of the hind limb) and, by the nature of their unique tendon and ligament anatomy, this locks the whole leg in place. This system is called the passive stay apparatus. When the stifle is locked the horse can rest on the leg which remains extended without any muscular effort. It can be seen at work when horses are standing tethered in a yard. One leg is resting, with the toe pointing to the ground while the other leg takes the whole weight of the rear of the horse.

Upward fixation of the patella is a condition where the horse is unable to unlock the stifle and therefore cannot flex the affected leg. Those horses that have a stifle joint with a very straight profile are more likely to develop this problem. Sometimes upward fixation develops secondary to trauma but equally, if the horse is out of condition, such reduced strength and conditioning of the support structures around the joint may also favour upward fixation.

Repeated episodes stretch the ligaments, and the condition may recur intermittently. If this is the case, the joint may become irritated and inflammation may set in (gonitis). This can occur in one or both hind legs.

Treatment centres on increasing the muscle mass and strength of the hindlimbs e.g. more hill and trotting work. Usually, gentle manipulation by a veterinary surgeon will resolve the condition but in severe cases where the condition reoccurs it may be necessary to surgically cut the medial patellar ligament while the horse is sedated. This is a minor procedure and when the ligament heals the condition is unlikely to reoccur. Your veterinary surgeon will discuss with you any concerns you have with your horse.

Your veterinary surgeon can provide advice on investigation and treatment of hind limb lameness and should be contacted if problems are suspected. Often the prognosis for return to soundness hinges on prompt treatment. There are many more conditions that can affect the horse’s hind limb and your health care team is a solid resource for information about those other conditions.