The humerus or upper arm is seldom broken. The large muscles which everywhere enclose it serve as a protection against external violence.

When this fracture does occur, and the breakage extends through the body of the bone, but little difficulty is experienced in the diagnosis.

The limb below the fracture displays unusual mobility. It is incapable of supporting weight, and when the animal is made to move, acute pain and lameness are evinced. The part is much swollen, and by carefully fixing the upper segment of the bone, and moving the lower one, crepitus may be developed.

Sometimes the external condyle is broken off, and the extensor muscles, losing their fixed point of action, and being at the same time more or less damaged, fail to antagonize the action of the flexors. As a consequence the leg is drawn inwards and the foot and pastern are flexed on the canon in such a way that the front of the hoof rests on the ground.

When the inner condyle is fractured and the attachment of the flexor muscles becomes weakened, the action of the extensor muscles, overpowering them, draws the foot forward, while the knee, losing its support from behind, falls backward. When weight is imposed upon the damaged leg, this backward inclination of the knee becomes more marked and the concavity in front of the limb is increased.

Treatment

When the shaft of the humerus is fractured there is not much hope of restoring the animal to a state of usefulness for ordinary physical labour. Where it is of special value for stud purposes an attempt should be made to effect re-position and bring about reparation.

The arm is a difficult place on which to apply a splint, and equally so to adjust a bandage with any prospect of its being retained. We would therefore advise that the patient be placed in slings, and that the ground be slightly hollowed out to receive the foot of the broken limb. A starch bandage must be applied from below the knee to the middle of the arm, and a thick pitch plaster round the humerus. With this, quietude must be enjoined, and the requirements of the patient supplied without disturbance.