SPAVIN. 995 



of the muscles of the hind limb produces excessive movement of the 

 hock-joint and great pressure on the articular surfaces, with danger 

 of injury to the ligaments of the joint. 



But these visible peculiarities of formation are not the sole causes 

 of spavin : the intimate structure of the bones and ligaments may 

 predispose to disease, as shown by the inheritance of spavin, and 

 its occurrence in entire . strains of horses with hock -joints perfectly 

 formed. In breeding, therefore, special attention should be paid 

 to this disease. The exact nature of the predisposition at present 

 eludes us, though by many it is considered to result from incomplete 

 development of the bones and ligaments. Working immature 

 animals is also a potent cause. Horses which might work quite 

 satisfactorily at five or six years old, not unnaturally develop spavin 

 at three or four. 



In considering the question of predisposition, we have to remember 

 that the formation of other portions of the limb, and even of the 

 body, exercises a considerable influence on the development of the 

 disease. Experience shows that uprightness of the fetlock- and 

 stifle- joints favours hock disease, though this formation is often 

 secondary, i.e., a consequence, and not a cause, of the formation of 

 spavin. Klemm considers that animals with cow-hocks, and those 

 which stand with the hind-feet far back, are predisposed to the disease, 

 and on this basis explains the curative action of shoes with high 

 quarters and deep heels. 



Peters thinks that turned-out hocks are particularly prone to 

 spavin, and there is no doubt that this formation interferes with 

 hock action and increases the chance of disease. 



Experience also shows that very powerful horses with broad 

 and well-developed quarters are particularly liable, the reason being 

 the great strain which this formation throws on the hock -joint. The 

 more powerful the muscles of the hind-quarter and the freer the 

 movement, the greater the strain on the hock. The same is true of 

 over-grown and long-backed animals. To produce an equal output 

 of energy, their muscles are forced to act more vigorously, and, 

 therefore, greater strain is thrown on the hock. For the same reason 

 powerful, spirited horses more often suffer than quiet, phlegmatic 

 animals. The fact that spavin is commoner in young horses is 

 principally due to the incomplete development of their bones and 

 ligaments, and to the existing predisposition being only brought 

 into play when the young animal is put to work ; horses, when once 

 seasoned, not being so likely to develop disease unless greater demands 

 are made on their working powers, or the hock is accidentally injured. 



