AS TO SOUNDNESS. 133 



not to be distinguished from " causticking" badly per- 

 formed, or the blow from another horse. If hocks have 

 been well fired, not too early in life, they are far less 

 likely to become lame from spavin than those which 

 have not been treated at all. 



Spavins situated very far back on the hock I have 

 never known to produce lameness. I have again and 

 again passed such, and have never had occasion to 

 regret it. Perhaps you had better mention it in your 

 certificate; or what is better, write a note with your 

 certificate and let your employer know you have not 

 overlooked the fact. 



Bog-spavin is one of the most wretched terms in our 

 nosology. It used to be called blood-spavin, from an 

 error in observation. You know the true hock joint 

 is a very large joint, and the bag, bursa, or purse which 

 secretes and contains the oil for its lubrication, is apt 

 to secrete and therefore to contain a little more oil than 

 is perhaps needful, and when this is so the bursa is dis- 

 tended and tense. A very large vein, called the saphena 

 vein (from the Greek o-a</»js, manifest or conspicuous), 

 passes directly over it and close to it and between it 

 and the skin. So that when the bursa distends, it 

 presses upon this vein and distends it, and makes 

 it more conspicuous ; hence the older anatomists, with 

 the feeble light of their day, thought that it was the 

 bursting of this vein into the joint which caused the 

 distended bursa, and so they named it blood-spavin. 

 It afterwards came to be known as bog-spavin, on 



