302 CHAPTER 38. 



effusion, as has been already explained in the Chapters on Inflammation 

 and Irritants, will be absorbed, and the remainder will solidify. In 

 accordance with the usual rule of Nature the deposition will partake of 

 the character of the part into which it is effused. In short it becomes 

 bone, or in other words a Spavin is formed. 



603. Liability to Spavin dependent on tlie Conformation of the Hock. 



The probability of the occurrence of Spavin in any particular hock is 

 mainly dependent on its conformation. If the hock is large and strong, 

 and its position is good and true as regards the incidents of the superin- 

 cumbent weight, it is not probable that it will be injuriously affected 

 either by concussion, weight, or sprain. But if there is any defect either 

 in the conformation, structure, or position, it will probably suffer in some 

 part or other ; and at that point sooner or later, according to the circum- 

 stances and nature of the work to which the animal is subjected, we are 

 likely to find disease. (See Plates 23 and 24.) 



604. Position of Spavin. 



It is impossible to define accurately the position of Spavin, but speak- 

 ing generally it may be described as being situated at the inner and lower 

 part of the hock joints. It varies in some degree according as weak or 

 defective structure, or improper position of the hind legs, or incidence of 

 the line of weight, or sprain of the ligaments, or such like causes may 

 induce pressure or concussion on any particular part. The greatest 

 pressure or concussion, however, are always felt towards the inner side, 

 and hence spavin is always found somewhere on that side. The most 

 common seat is between, and towards the front of the cuneiform bones. 

 See Plate 22. 



Spavins may occur on the exterior of the bones. In such cases they 

 are easily seen and felt, and hence are called " detectable;" or they may 

 occur between the bones, in which case there may be little or no external 

 enlargement. These are termed " occult " spavins. During the forma- 

 tion, however, of the exostosis some degree of extra heat and tenderness 

 on pressure may generally be detected. After consolidation, the existence 

 of occult spavins in many cases can only be defined by the nature of the 

 lameness they produce. (For signs of lameness arising from spavin see 

 below, paragraph 606.) 



As a general rule exostoses on the exterior of the bones arise from 

 sprains of the ligaments of the hock, whilst those between the bones are 

 produced by pressure and concussion. 



604a. Occult Spavins. 



The evidences or symptoms afforded by Occult spavins are inferential 

 or negative rather than positive, and our surest guides to their recogni- 

 tion consist in the continuous and painful lameness, which arises from 

 attrition of the ulcerated surfaces of the bones, and local heat, sometimes 



