Page 370 - The Veterinary Care of the Horse

DIAGNOSIS

Diagnosis is made on:
VetBooks.ir • the history

•
the clinical signs
• nerve blocks

• radiography

• scintigraphy.

Nerve blocks

Intra-articular anaesthesia (i.e. nerve blocks of the hock joint) is important for early diagnosis
of DJD of the distal hock joints in some horses because radiographic changes may not be

visible at this stage of the disease. In other cases, however, the horse may not become lame
until the radiographic changes are advanced.

Radiographic changes
These include:

• spurs of new bone at the joint margins

• increased or decreased density of the subchondral bone directly under the articular
cartilage

• widening of the joint space

• narrowing or loss of the joint spaces (see Figure 8.6b).

There is poor correlation between the extent of the radiographic changes and the degree of

lameness. Horses may have extensive changes at the time the lameness is first recognized.
Others may be severely lame with no changes visible on radiographs.

The use of scintigraphy
Scintigraphy is not usually necessary but is helpful in cases where:

• the horse is uncooperative and cannot be safely nerve blocked

• multiple joint problems are contributing to the lameness.

Horses can have positive scintigraphy results despite having no changes on X-ray and so the

technique is useful in these cases.