CAUSES OF UNSOUNDNESS. 125 



lameness may, or may not, spring into existence. 

 Most of these enlargements are of gradual onset, 

 but not necessarily so ; in fact, they may make 

 their appearance in a single night. But in this 

 case it is usual for the swelling to be accompanied 

 by increased heat, pain, lameness, and a degree 

 of fever. 



Psoriasis. 



This is a skin disease attacking the front face of 

 the hock joint, and although apparently but 

 trifling, experience shows it to be a most intractable 

 complaint, and one that causes— or should cause-— 

 rejection. It constitutes unsoundness, being a 

 chronic form of eczema. The same disease also 

 appears upon the back of the knee joint, and the 

 old terms '' mallenders " and "sallenders" were 

 employed by horsemen to indicate this disease ; the 

 former term when it appeared at the knee, and the 

 latter when at the hock. 



String-halt. 



In this disease the animal lifts one or both hind 

 legs suddenly up in a jerky manner, both in and 

 out of the stable, but it is most readily observed 

 when the animal is turned suddenly round, or 



