Notwithstanding the large muscles which everywhere surround and protect the femur, it is sometimes made to yield to the violence which in one form or another is applied to it. The causes which determine fracture of this bone are mostly kicks from other horses, violent struggling while undergoing operations or in endeavouring to escape from some difficult and confined position. It sometimes results from a slip while attempting to start a heavy load.

The seat and nature of the fracture varies in different cases. Sometimes the head is broken off through the neck, at others the diaphysis or shaft is divided in a transverse or oblique direction (fig. 328), or one or both condyles may be separated from the inferior extremity of the body, or the large trochanter broken away from the upper extremity of the bone. The signs of fracture here are not usually difficult to read. Sudden and acute lameness, with inability to bear weight, and difficulty in advancing the limb, are at once manifest. When the animal is made to move, the leg is advanced with an outward swing and displays unnatural mobility. Crepitation is made apparent by passive movement of the broken pieces, first in one direction and then in another. As the animal stands, the quarter sinks into a resting position.

Reposition or reduction of the fracture is always difficult, mostly impossible; and when accomplished the size, form, and relations of the thigh oppose the application of appliances to retain the broken fragments in apposition. It will be seen, therefore, that unless great value is set upon an animal for breeding purposes treatment is not likely to prove remunerative, and should not be encouraged.

An unserviceable cripple is with very rare exceptions the only return for much expense and trouble.

Slinging, pitch plasters over the part, and such quietude as can be procured are the only available if doubtful means of effecting a reunion of the parts.