Page 575 - The Veterinary Care of the Horse

Causes

These include the following.
VetBooks.ir • Falls, e.g. slipping and falling sideways on a hard surface or during a competition.

• Rearing up and falling over backwards.

• Road traffic accidents

• Knocking the tuber coxae on a gate post or stable door frame.

• Uncoordinated attempts to get up whilst being cast.
• ‘Stress’ fractures: in young racehorses, the bones of the pelvis constantly remodel as an

adaptation to the powerful forces experienced during training. Stress fractures occur if
these forces exceed the capacity of the bone to withstand them and are common in young

racehorses.

Clinical signs

These depend on the site of the fracture. The commonest sites are the wing and shaft of the
ilium. All fractures are associated with a sudden onset of moderate to severe lameness often
accompanied by soft tissue swelling. In the case of stress fractures in young horses, this may

be preceded by periods of intermittent, slight hind limb lameness, poor performance or
altered hind limb gait. The fracture usually affects only one side of the pelvis giving a

unilateral lameness. Occasionally, catastrophic bilateral stress fractures occur and the horse is
unable to walk or support itself comfortably.

FRACTURES OF THE ILIAL WING

The wing of the ilium is the commonest site for a stress fracture.
• Incomplete fractures (consisting of tiny microfractures that do not go all the way through

the bone) are associated with a shortened stride, poor propulsion and loss of performance.

• The horse will sometimes change its gait and plait behind at trot.
• Complete fractures cause variable degrees of lameness. A moderate to severe lameness

may be present for the first 48 hours followed by a marked improvement.

• The tuber sacrale on the affected side may be lower than the opposite tuber sacrale due to
displacement of the fractured part of the bone (Figure 12.24).

• Pressing firmly on the skin over the displaced tuber sacrale is usually very painful and
causes muscle spasm.

• There may be gradual wastage of the gluteal muscles with an incomplete stress fracture.

Marked wasting of the muscles occurs within two weeks of a complete fracture occurring