Page 481 - The Veterinary Care of the Horse

The prognosis is variable following surgery as the condition will recur in some horses.

VetBooks.ir SHIVERING

Shivers or shivering is a condition where the horse intermittently flexes a hind limb, lifting it
abnormally high and holding it away from the body. This is an involuntary action,

accompanied by quivering of the hind limb muscles and the tail. The first signs are usually
seen when the horse is between 2 and 4 years of age. Male horses around 17 hands seem to
be most susceptible.

Cause

The cause is unknown. The following have been suggested:

• mild spinal cord lesions

• arthritic degeneration of the lumbar spine
• pain

• polysaccharide storage myopathy (PSSM)

• It has been suggested that shivering may be inherited; the condition is seen in draught

breeds and Warmbloods more than other breeds. Thoroughbreds may also be affected.

Clinical signs

• It characteristically occurs when the leg is lifted or the horse is pushed backwards. It is

also likely to be seen when the horse moves off after standing still or is turned in a small
circle (hence these procedures are included in a prepurchase examination).

• The first sign may be an intermittent reluctance to lift the hind limb for shoeing or to
walk backwards.

• When the limb is lifted, the leg is flexed in an exaggerated fashion and often held away

from the body for several seconds.
• The tail head is usually raised and may quiver.

• The thigh muscles often tremble spontaneously.

• The signs are not seen at trot or canter.

• The signs may be worse if the horse is exercised infrequently, the weather is cold or the
horse is anxious.

• The condition can vary from day to day and may not be apparent some of the time.