52 SPEAINS. 



is that in which the legs more or less "fine down " hj exercise, and 

 " fill " airain after the animal has been in his stable for some time. 

 The best treatment is the application of cotton wadding bandages 

 (p. 45), immediately after the horse returns from work, and hand- 

 rubbing. It is evident that our object should be to prevent the 

 occurrence, and to lessen the amount, of the swelling which inter- 

 feres with the blood-supply of the part. Before the horse is taken 

 out again, the cotton wadding bandages should be removed, and the 

 legs well hand-rubbed (p. 666). Although purgatives and diuretics 

 may relieve the swelling for the time being, they in no way remove 

 its cause. Besides, their frequent use would injure the animal's 

 liealth. 



Curb 



is a swelling which appears at the back of the hock, about six inches 

 below its point, in a full-sized horse. It is caused by an enlargement 

 that displaces the back tendons, at the affected spot, out of the 

 straight line they normally preserve from point of hock to fetlock 

 (Figs. 26 and 27). 



NATURE OF THE DISEASE.— The bones at the back of the hock are 

 strongly bound together by a mass of ligamentous fibres (Fig. 28) which are 

 attached to the os calcis, to the large and small cuneiform bones, to the cuboid 

 bone, and to the heads of the splint bones and of the cannon bone (Fig. 29). 

 The rigid bar (or united column of bones) thus formed from point of hock to 

 fetlock, acts, in conjunction with the bones below the fetlock and with the 

 hoof, as a lever for straightening out the hock when the foot is on the ground ; 

 for instance, during propulsion in the various paces, in leaping, and in sup- 

 porting the body when the horse rears. Here we have a lever of the second 

 order, in which the fulcrum is the ground ; the weight, the resistance offered 

 by the head of the tibia, through which bone the propulsive or weight-bearing 

 effort is transmitted ; and the power, the muscles (those of the gaskin) which 

 are attached to the point of the hock. It is evident that in the working of this 

 lever, strain will be thrown on the ligaments which preserve its rigidity. 

 Hence, during violent efforts to straighten the hock, or to prevent it from 

 becoming bent, while the foot is on the ground, some of the binding liga- 

 mentous fibres are liable to give way, naturally at their weakest point, which 

 will be one or other of their points of attachment on small surfaces of bone ; 

 that of the cuboid bone or head of the outer splint bone, for example. As 

 their attachment to the back of the os calcis is of large extent, their connection 

 with it is not likely to be severed. A serious giving way of the ligaments will 

 be followed by displacement of the bones of the hock, in which case the point 

 of the hock (upper end of the os calcis) will be drawn forward, similarly to 

 what happens in " fiat foot " of man, of which Fig. 30 shows an aggravated 

 instance. We should here bear in mind that the heel of man corresponds 

 to the point of the hock of the horse. In ordinary cases of curb, the injury 

 seems to consist of the tearing away, to a greater or less extent, of liga- 

 mentous fibres from their bony attachments, with little or no displacement of 

 the column of bones ; the result being — agreeably to the remarks made by 

 Goubaux and Barrier on bone tumours, see page 230 — that a bony enlarge- 

 ment forms at the back of the hock as a consequence of strain which has too 

 severely taxed the strength of the ligamentous brace in question. When the 

 enlargement is on or near the cuboid bone, the back tendons will be more or 



