22S DICTIONARY OF THE VETERINARY ART. 



or suddenly pulling up at full speed, racing before the horse 

 shall have arrived at maturity, while the joints are yet in 

 a state of imperfection, very frequently lay the foundation 

 of exostosis. The parts being sprained and taxed beyond 

 endurance, disease is excited in the ligamentous substance, 

 and extends itself to the periosteum and bones ; the ligaments 

 often become ossified, and are rendered fixtures ; the perios- 

 teum, being raised by bony accumulations, presents itself in 

 the situation of splents, spavin, or ringbone. 



Sir A. Cooper divides exostosis, in reference to its seat, 

 into two kinds — periosteal and medullary; and again, as 

 to its nature, into cartilaginous and fungous. "But," says 

 Mr. Percival, J£ it is to that kind only which is situated 

 between the shell of the bone and the periosteum covering it, 

 that we have to attend in veterinary practice. On dissection 

 we find the periosteum thicker than usual, with cartilage 

 beneath it, and ossific matter within the cartilage, extending 

 from the shell of the bone nearly to the internal surface of 

 the periosteum, still leaving on the surface of the swelling a 

 thin portion of cartilage nnossified." 



When the accretion of these swellings ceases, and the dis- 

 ease has been of long standing, they are found to consist on 

 their exterior surface of a shell of osseous matter similar to that 

 of the original bone ; consequently, when an exostosis has been 

 formed in the manner here described, the shell of the original 

 bone becomes absorbed, and cancelli are deposited in its place. 



" In the mean time, the outer surface of the exostosis ac- 

 quires a shell resembling that of the bone itself. When the 

 exostosis has been steeped in an acid, and by this means 

 deprived of its phosphate of lime, the cartilaginous structure 

 remains of the same form and magnitude as the diseased de- 

 posits ; and as far as I have been able to discover, it is effused 

 precisely in the same manner as healthy bone. 



" An exostosis, abstractedly considered, does not appear to 

 occasion much inconvenience to the animal, except in the 

 early stages. A ringbone, confined to the pastern bones, is 

 of little consideration ; but should it show itself at or near 



