1016 DISEASES OF THE HOCK. 



a right angle, the more powerfully does the gastrocnemius act, and, 

 oonsequently 3 the more likely is this ligament to become strained. 



In " tied -in " hocks the lower row of bones and the upper end 

 of the metatarus are too slight ; the distance between the calcaneo- 

 metatarsal ligament and the anterior margin of the hock, which 

 represents another lever, is too short. The less this distance, the 

 more liable is the ligament to be strained and inflamed when the limb 

 is forcibly extended during movement. 



The exciting causes consist in severe exertion, violent attempts 

 at extension at moments when the limb is flexed and sustaining 

 weight, as in jumping, or in heavy or uphill draught-work. Curb 

 sometimes results from the horse being suddenly thrown on its 

 haunches. The more powerful the muscles of the quarter and limb, 

 the greater the strain on the ligament, a fact which explains the 

 frequency of curb in very powerful horses. 



Symptoms. Change in the form of the joint. Curb appears 

 as a swelling in the otherwise straight line of the hock when seen 

 from the side (Fig. 544). Careful examination and palpation 

 differentiate strain of the calcaneo-metatarsal ligament from disease 

 of the tendon, tendon sheath, or skin, or enlargement of the head 

 of the external small metatarsal bone. Lameness is seldom well 

 marked in curb, which, in many horses, may form little more than a 

 blemish. When occurring, lameness is due either to co-existing 

 disease, or to inflammation arising from strain or partial rupture 

 of the calcaneo-metatarsal ligament. Curb, when slowly developed, 

 may not interfere with movement, but when caused by violent injury 

 with rupture of the ligament is often accompanied by sudden and 

 severe lameness, which, however, in most cases rapidly diminishes. 

 In side movement, pain is shown when weight is thrown on the limb, 

 the fetlock is flexed, and the horse steps over on the toe ; at rest, 

 the heel is raised. In such cases pain and increased warmth may 

 be detected on pressure over the affected spot. These symptoms 

 generally disappear in from one to three weeks, but the swelling 

 persists. Young horses in regular work are liable to suffer from 

 relapse. 



Prognosis. The gravity of curb varies greatly. In general, 

 and particularly in old working-horses, it is simply a blemish, but 

 animals exhibiting large or diffused curb should not be used for 

 breeding, especially if the formation of the hock -joint be defective. 

 In young animals, and in cases accompanied by chronic or inter- 

 mittent lameness, prognosis depends partly on the extent to which 

 the animal's usefulness is affected, partly on the formation of the 



