58 SPRAINS. 



with lameness, and wliicli were caused by the horse's foot getting 

 caught in a fence when jumping. 



In sprung hock, there is high fever and great pain. 



TREATMENT. — ^Put the animal into slings ; for he will not lie 

 down to rest, because the injury is in a hind leg ; and treat as 

 described on pages 26 to 28, and 44 to 49. 



After this accident, the animal should have about eight or nine 

 months' rest, which will jDrobably render him capable of doing useful 

 work. 



Sprain of the Shoulder. 



ANATOMY.- — The shoulder joint (Fig. 31) is formed by the shoulder-blade 

 (Fig. 115) and humerus. This ball-and-socket joint being required to possess 

 great power of extension and flexion, as well as some side play, is bound down 

 by only one ligament (the capsular) ; the office of other ligaments being taken 

 by the tendons of certain muscles which pass over it, and thus help to keep 

 it in place. A large muscle (the -flexor brachii) takes its origin at the head 

 of the shoulder-blade, passes over the shoulder joint, and is attached to the 

 head of the radius. Its action is to straighten the shoulder joint and raise 

 the knee. The shoulder joint is kept close to the side by the pectoral muscles, 

 which connect it, above and below, to the body, and thus prevent it from 

 bulging outwards. Two of these muscles (the deep pectorals) act in drawing 

 the point of the shoulder backwards and downwards. 



NxA^TURE. — The shoulder is so large, and its com^ponent parts 

 so concealed from sight and touch, that, in the case of shoulder 

 lameness, it is often very difficult to locate the seat of injury. 

 Formerly, sprain of the pectoral muscles was regarded as the most 

 frequent cause ol this lameness, on account of these muscles 

 generally being, in such cases, unable to perform their usual 

 function of keeping the shoulder joint close to the body. This 

 muscular inability is also seen in fracture of the first rib (p. 310), 

 which is a frequent cause of shoulder lameness. We may also have 

 sprain of the flexor brachii, sprain of the capsular ligament, and 

 injury to the ner\^es of the part, or to the joint itself. 



Cx4lUSES. — The usual causes are : (1) over-exertion of the pec- 

 toral muscles, which is specially liable to occur with young horses 

 when ploughing, to which they are put, as a rule, at an earlier age 

 than to any other kind of labour ; (2) wrenches when turning, and 

 slips, by which the shoulder is pulled forcibly outwards and some- 

 times forwards, in direct antagonism to the action of the pectoral 

 muscles ; and (3) falls or blows, by which the joint and its neigh- 

 bouring parts may be injured. 



SYMPTOMS. — When the pectoral muscles are affected, the ijoint 

 of the shoulder is seen to bulge out at each step, and the foot is 

 swung outwards as it is brought to the front, as in fracture of the 



