Page 440 - The Veterinary Care of the Horse

• If the affected area is painful, the horse should not be ridden.

• Flushing the blocked nasolacrimal ducts with sterile saline and a dilute antibiotic solution
VetBooks.ir may be helpful.

PROGNOSIS

The condition usually resolves spontaneously over a period of 12–18 months. The bony
swelling reduces in size and may disappear altogether. Some horses are left with a permanent

blemish.

Sesamoiditis

Sesamoiditis can be defined as inflammation of the proximal sesamoid bones.

ANATOMY

There are two small proximal sesamoid bones at the back of the fetlock, one on either side of

the limb. The suspensory ligament divides into medial and lateral branches in the lower third
of the metacarpal and metatarsal regions. The medial branch attaches to the top and outside
of the medial sesamoid bone and the lateral branch attaches to the top and outside of the

lateral sesamoid bone before they run obliquely across the first phalanx (P1) to join the
common digital extensor tendon. The lower edges of the sesamoid bones are attached to the

first and second phalanges (P1 and P2) by three ligaments. The two sesamoid bones are
directly joined by the intersesamoidean ligament. (See figures 7.10a and b.)

In this condition, a periostitis occurs at the sites of ligament attachment and new bone
deposits (called enthesiophytes) may be formed. Degenerative bony changes may also occur

as a result of the inflammation or altered blood supply. The condition is seen most commonly
in animals that do fast work; racehorses are particularly susceptible and it is commonly

reported in Standardbreds. Sesamoiditis may be associated with suspensory ligament injuries.

CAUSES

• Tearing of the suspensory or distal ligament attachments when the fetlock joint is over-

extended. This tends to occur when tired horses work or jump at speed.
• An acute sprain.

• Direct trauma, e.g. an overreach.

• Long-toe conformation increases susceptibility to this injury.

CLINICAL SIGNS