In our minds there is no doubt that many of the occult and chronic forms of foot-lameness we meet with in practice are in this way to be accounted for.  We may, in fact, explain them by suggesting either a chronic synovitis alone, or a synovitis complicated with periostitis.

Treatment of Synovitis.—­If a joint has been injured, as we have suggested, by slight blows or other causes—­in other words, if the injury is subcutaneous, and no wound is in existence—­then there is no treatment which offers better results than does the continued application of cold.

At the same time, the animal should be slung, or, if non-excitable and inclined to rest, allowed at intervals to lie on a thick and comfortable straw bed, the cold fomentations during such intervals being discontinued.  When the case is a marked one and the animal valuable, benefit will be derived from the application of crushed ice.

The animal’s condition must be watched, and the case helped as far as is possible by the administration of a mild dose of physic, by saline drinks, and, when necessary, by the giving of small but repeated doses of Fleming’s tincture of Aconite in order to relieve the pain.  In a chronic case the repeated application of a blister is indicated.

(b) PURULENT OR SUPPURATIVE SYNOVITIS.

In this condition we have synovitis complicated by the presence of pus.  Unlike the simple form, it shows a marked disposition to spread, and quickly involves the surrounding structures.  Very soon the ligaments of the joint, the periosteum, the articular cartilages, and the bones are implicated.  This, of course, constitutes a condition of acute purulent arthritis.  Under that heading, therefore, the condition will be later discussed.

B. ARTHRITIS.

(a) SIMPLE OR SEROUS ARTHRITIS.

With an attack of simple synovitis it may be always assumed that the changes commenced in the synovial membrane, communicate themselves more or less readily to the surrounding tissues, and are not confined to the synovial membrane alone.  We may thus have the inflammatory phenomena asserting themselves in the surrounding ligaments, in the periosteum, in the bone, and in the articular cartilages.  It depends, in fact, upon the severity of our case whether we call it synovitis or arthritis.  The two conditions merge so the one into the other that no hard-and-fast rule may be laid down whereby they may with certainty be differentiated.  Such symptoms, therefore, as we have given for synovitis may be also read as indicating a condition of simple arthritis.  The course of the case will be very similar, and the treatment to be followed identical with that just given.

(b) ACUTE ARTHRITIS.

Causes.—­An attack of acute arthritis may commence with the affection of the synovial membrane, and spread from that to the other structures.  In other cases the disease of the synovial membrane, and after it the disease of the joint, may be secondary to diseases commencing in the structures around the joint.  This affection may therefore follow on a case of acute coronitis, a case of suppurating corn, a case of quittor, a severe case of tread, or may attend a case of laminitis.