300 HEALTH AND DISEASE 



rabbit holes while galloping, or when fixed in railway points, as occurs, 

 to horses engaged in shunting. 



Symptoms. — In sprain to the tendons of this muscle the horse moves 

 the leg forward with diffic-ulty. There is inability to bend the hock, and 

 the limb is carried forward with a slight outward swing. When standino- 

 the heel of the foot is raised and the hind-quarter is depressed. Heat and 

 slight swelling over the seat of injury will be observed, and deep pressure 

 causes pain. 



Where, as sometimes occurs, the muscle becomes ruptured, tlie leg- 

 is drawn directly backward and the sole of the foot inclined upward. 



The gastrocnemii tendons (hamstrings), having now nothing to anta- 

 gonize their action, become relaxed and thrown into folds. 



Treatment. — Complete rest and cold-water irrigation should first be 

 resorted to, and is usually all that is needed. Where, however, lameness, 

 continues after sprain of the tendon has been so dealt with for two or 

 three weeks, a blister should be applied to both sides of the hock-joint, 

 and repeated if necessary. It mu.st on no account be applied to the front 

 or bend of the joint, where the tendons are situated. 



CURB 



A curb is an enlargement on the posterior part of the hock -joint,, 

 about 4 or 5 inches below its point. Pathologically it consists in an in- 

 flammatory thickening of the sheath of the flexor pedis perforans tendon 

 as it passes down the back of the leg. An enlargement of the calcaneo- 

 cuboid ligament, i.e. a strong ligament uniting the bones of the hock 

 behind with the splint and canon bones below, is also spoken of as curb 

 by some, and l)y others certain forms of spavin are included in the term. 



Causes. — Curbs are common to all varieties of the horse, but they are 

 most frequently seen in the lighter breeds, and especially in hunters and 

 thoroughbreds. 



The causes out of which they arise must be considered under two heads,, 

 viz. predisposing and exciting. Of the former, heredity is a marked 

 factor quite apart from conformation, for it is noticeable that the produce 

 of some hor.ses and mares, against the make and shape of whose limbs- 

 nothing can Ije said, show a special liability to the disease. It must lie 

 observed, however, that conformation is a conspicuous feature in the 

 origin of curb. Animals with .short calces, or, in otlier words, wantin 

 in prominence and length of liock-point, are .singularly liable to the disea.se,, 

 and the same may be said of others whose hind-liml)s slope unduly for- 

 ward, and are brought more immediately under the weight of the l)ody. 



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