DISEASES OF THE HOCK. 301 



its glistening, polished appearance is undoubtedly due to the 

 friction. 



What is termed a Uood-spamn is simply a distended con- 

 dition of the vena-saphena, caused by the pressure of a bursal 

 or bony enlargement. It has been described as a disease of 

 the vein, and in some rare instances a varicosity has actually 

 existed. 



In rheumatoid diseases of the hock-joint, the crackling sound 

 caused by the first movements of the articulation, already 

 described, has been noticed by some veterinarians. Thus, the 

 late Mr. Farrel of Dublin was able to prognosticate the 

 incurability of hock-joint disease when it was accompanied 

 by that sound. 



What is commonly called a "sprung JiocW is an enlarged and 

 inflamed condition of the tarsus generally, involving the struc- 

 tures of the whole articulation, arising from severe sprain, and in 

 some instances associated with fracture of one or more of the 

 smaller bones. 



This injury causes extreme lameness, and fever ; prevents the 

 animal from lying down and taking its natural rest ; and is 

 thus a cause of rapid loss of condition, and sometimes of death. 



The special treatment is that calculated to allay irritability, 

 fever, and the local pain; and in order that the animal may 

 obtain some degree of rest the slings are essential ; and when 

 the acute symptoms have subsided, repeated applications of the 

 biniodide of mercury ointment to stimulate the absorption of 

 the callous enlargements, and perhaps setons or the actual 

 cautery to remove any remaining lameness. 



II. DISEASES OF THE GLIDING AETICULATIONS OF THE HOCKS. 



Bone- Spavin. — Bone-spavin is a very common cause of lame- 

 ness and unsoundness, and it is of importance that a veterinary 

 surgeon be a good judge of a hock ; for what may be a spavin in 

 one horse may be a mere peculiarity of conformation in another. 



Definition. — The derivation of the word spavin is buried in 

 obscurity ; but it is thought by some to be derived from the 

 Italian spavenio, a disease of horses — an unsatisfactory ex- 

 planation. I find, however, that Eokitansky describes a lamellar 

 bony tumour as " spavined ; " possibly the word may have some 

 connection with that form of exostosis. A bone-spavin may be 



