Page 426 - The Veterinary Care of the Horse

away. As the inflammation subsides, the bony lump remodels, becoming smaller and

painless.
VetBooks.ir Radiographic changes

The new bone is visible from approximately two weeks after the injury occurs. While the

inflammation is still active, the new bone appears less dense than the normal bone and has a
fuzzy and irregular outline. As the inflammation subsides, the bony lump remodels. It

acquires a smooth contour and remains as a bony lump or exostosis.
Examples of periostitis include sore shins and splints.

Sore (bucked) shins

The veterinary term for sore shins is dorsal metacarpal (metatarsal) disease. The condition

usually affects the forelimbs; the hind limbs are only occasionally involved. In this condition,
the dorsal aspect (front) of the third metacarpal (cannon) bone becomes inflamed and sore. It
is very common in 2-year-old Thoroughbred horses in training.

CAUSES

The disease occurs when the immature bones of young, growing Thoroughbreds are
subjected to the stresses of racing and training. Fast exercise causes compression of the front

of the cannon bone. In response to this, the bone remodels and becomes thicker as an
adaptation to the demands placed on it. If the speed and distance in the training programme

are increased too quickly, however, the bone cannot adapt fast enough and the resultant stress
on the bone causes inflammation and pain.

CLINICAL SIGNS

These may include:
• heat

• pain when the shins are palpated

• an alteration of gait ranging from a slight shortening of stride or stiffness, to severe
lameness

• reduced performance level

• the front of the cannon bone may become convex in outline (Figure 10.2)
• improvement with rest but the soreness recurs with further exercise.