? EXOSTOSIS. 469 
tion of the tendons at their point ‘of insertion, gives rise to a lameness of 
Jong duration, due to the periostitis and tendinitis, while it grows and in- 
‘terfering with the function after its full development. Ona three-year-old 
that we watched the lameness lasted fifteen months. On another, for two 
years after there remained some stiffness at the start. Most of the 
practitioners who have seen this lesion believe that it is the sequele of a 
‘fracture of the suscarpal bone. 
As soon as the diagnosis is made by the lameness, the sensibility and 
a slight swelling of the part, rest must be prescribed. If blistering and 
firing do not obtain the removal of the bony neoformation, they often 
have the advantage of removing the lameness. For osselets that resist 
firing, median neurotomy is indicated. 
_ LL.—Spavin-—Tarsal Osteo-arthritis. 
The hereditary transmission of some defective conformations of the 
hock (narrow, bent), perhaps also a want of resistance, plays an important 
part in the development of spavin. Through the efforts of pulling, rapid 
traveling, rearing, jumping, the articulation of the hock receives pressures 
liable to injure the ligaments, synovials and bones; specially in young 
animals, whose organs have not reached their ful! development, these are 
the principal causes of the disease.’ 
If spavin is sometimes only a high placed exostosis, most generally it 
invades tarsal articulations. In that case, it is at times superficial, due to 
ligament tears, and forms on the lower tarsal articulations a kind of callus, 
assisting ankylosis (Aronsohn); at others, and more frequently, it is the 
expression of several dry arthritis which result in the ankylosis of the in- 
flamed joints. According to the seat of the bony tumor, we consider the 
metatarsal spavin, occupying the superior part of the internal face of the 
cannon, and the ¢arso-metatarsal or articular, spreading over the articula- 
tions of the hock. This last offers several varieties : in the first, the 
external tumor and the ankylosis are limited to the articulation of the 
cuneiform bones with the metatarsal; in the second, the ‘lesions involve 
also the joint of the scaphoid and cuneiforms; in the last, the astragalus is 
‘united to the scaphoid. In a similar way, spavin is spread more or less 
transversely and when its dimensions are reduced, its prominence is 
‘situated at times forward, towards the bend of the knee, at others more 
backward. 
During the development of spavin, when the lameness is already very 
great, often no abnormal projection is detected at the base of the hock ; 
morbid sensibility is very little marked or absent, which renders the 
diagnosis difficult and shows that the lesions truly began in the bottom 
