This form of the disease most commonly presents itself in that affection of the limbs termed sore shins and splints.

It may, of course, attack any of the bones of the skeleton, but those of the legs are by far the most frequently involved. See Sore Shins and Splints.

Acute Ostitis is comparatively of seldom occurrence in the horse. Why this should be so it is difficult to say precisely, but the absence of those constitutional conditions which favour its production in man is no doubt in some measure a safeguard against it in our equine patients. The fact that amputation is but seldom resorted to in the horse may also contribute to render him less frequently the victim of this disease.

It is mostly observed in the bones of the extremities, and especially those below the knees and hocks.

Sometimes it is localized or confined to a particular part, or it may involve a large tract, or even the entire bone. The writer has seen the whole of the os suffraginis or large pastern bone destroyed, and its remains enclosed in a perforated shell of bony matter, formed around it by the periosteum (figs. 317, 318). It sometimes occurs in the upper and lower jaw-bones.

Causes

Acute ostitis is the result of injury inflicted on the bone by external violence, the most severe cases being those in which the bone is penetrated by some sharp instrument, as when the foot bone is punctured by a nail. The example figured was caused by the foot of the horse being brought violently to the ground when attempting to save himself in slipping. The disease may also occur in connection with fracture of the hone when the result of extreme violence.

Fig. 317. - Acute Ostitis.

1, Sequestrum or Slough. 2, 2, Cloacae or openings for escape of pus and dead bone. 3, 3, New bone enclosing the sequestrum.

Fig. 318. - Acute Ostitis.

1, Sequestrum or Slough. 2, New bone enclosing sequestrum.

Symptoms

When occurring in the bones of the extremities, it is attended with acute lameness and suffering. The parts around the bone are much swollen, hot and tender, and considerable difficulty may be experienced in defining the precise stage and nature of the disease. Sooner or later an abscess forms, followed by another and another, from which flows a blood-stained and offensive matter.

Later the bone begins to crumble away, and the debris escapes in granular particles with the discharge. The tendency in these cases is to blood-poisoning, and the formation of abscesses in one or another or several of the internal organs. It is seldom that the patient recovers from such an attack so as to be again useful.