Page 368 - The Veterinary Care of the Horse

unilateral lameness.

• The stiffness is most apparent at the start of exercise and wears off as the horse warms
VetBooks.ir • up.

Where only one limb is affected or the changes in one limb are more advanced than in

the other, the horse appears unlevel or lame.
• Lameness may be more obvious with the horse lunged on a circle or when it is ridden.

• If the horse has a few days of hard work the lameness may become more pronounced.

• If the horse is rested and turned out for a few days the lameness often becomes less
pronounced.

Flexion

Affected horses are often uncomfortable when the hind limb is held in the flexed position for
shoeing. In advanced cases, flexion of the hock may be markedly reduced.

Most affected horses show a positive reaction to a spavin or hock flexion test. If the hock
is flexed for a minute and the horse is trotted off on a hard flat surface, the lameness is

usually accentuated for a variable number of strides. It must be remembered that this test is
not specific for hock pain as other joints are flexed at the same time. A negative spavin test

does not rule out a diagnosis of bone spavin.

Swelling

Horses can have distal hock pain with no change in the appearance of the limb. However, as

the osteoarthritis progresses, a soft tissue or bony enlargement may develop on the medial or
dorsomedial aspect of the hock at the level of the distal intertarsal or tarsometatarsal joints

(Figures 8.11a and b). If the disease is bilateral or the horse has naturally boxy hocks this can
be difficult to appreciate.