lameness: its causes and tkeatment. 371 



sprains of suspensory ligaments and of flexor tendons or their 



SHEATHS. 



The fibrous structure situated behind the cannon bones, both in the 

 fore and hind legs, is often the seat of lacerations or sprains resulting 

 from violent efforts or sudden jerks. 



Cause. — The injury may be considered serious or trifling, according 

 to the circumstances of each case as judged by its own history. Among 

 the predisposing causes are a long, thin fetlock and a narrow knee or 

 hock as viewed from the side, with the flexor muscles tied in just below 

 the joint. The longer and more oblique the pastern the greater is the 

 strain on the flexor tendons and suspensory ligaments; hence a low 

 quarter, a toe calk, and no heel calks, or a thin calk placed at the tip 

 under the toe, and leaving the quarters long abnormally stretches the 

 back tendons and causes a great strain upon them just before the 

 weight is shifted from the foot in locomotion. In runners and hunters 

 the disease is liable to be periodic. In driving horses it is most com- 

 mon in well-bred animals of nervous temperament. Draft horses 

 suffer most frequently in the hind legs. 



Symptoms. — ^The injury is readily recognized by the changed as- 

 pect of the region and the accompanying local symptoms. The parts 

 which in health are well defined, with the outlines of the tendons and 

 ligaments well marked, become the seat of a swelling, more or less 

 developed, from a small spot on the middle of the back of the tendon 

 to a tumefaction reaching from the knee down to and even involving 

 the fetlock itself. It is always characterized by heat, and it is vari- 

 ously sensitive, ranging from a mere tenderness to a degree of sore- 

 ness which shrinks from the lightest touch. The degree of the lame- 

 ness varies, and it has a corresponding range with the soreness, some- 

 times showing only a slight halting and at others the extreme of 

 lameness on three legs, with intermediate degrees. 



The lameness is always worse when the weight is thrown on the 

 foot and is most marked toward the end of the phase of contact with 

 the ground. Either passive irritation of the leg or turning the ani- 

 mal in a circle causes pain as in diseases of the joints. Sometimes the 

 horse likes to get the heels on a stone or some elevation so as to relieve 

 the weight from the flexor tendons. Finally, in cases of long stand- 

 ing, a shortening of the tendons occurs, resulting in the abnormal 

 flexion of the foot known by horsemen as " broken down," or a more 

 upright position of the foot may follow, producing perhaps knuck- 

 ling or the so-called clubfoot. 



Prognosis. — It may be safely assumed on general principles that a 

 leg which has received such injuries seldom returns to a perfect con- 

 dition of efficiency and soundness, and that as a fact a certain abso- 

 lute amount of thickening and deformity will remain permanent, 

 even when the lameness has entirely disappeared. 



