190 PBINCIPLES OF TETERINAEY SURGEBT 



"bralis; by pressure from keraphyllocele -upon the os pedis thg 

 latter wastes. The pressure of an aneurism against the verte- 

 bral column produces thinning of the latter, etc. 



In chronic lameness, such as from spavin or ringbone, not 

 only wasting of certain muscles sets in, but also an inactivity 

 atrophy of the metacarpus or metatarsus. 



Senile atrophy of bones leads to fractures of the vertebral 

 column when aged horses are thrown for operations. 



In such diseases as actinomycosis and osteoporosis, osteo- 

 malacia, etc. , an inflammatory atrophy is seen as a sequel to 

 a rarefying osteitis, the atrophic changes being the result of 

 the action of the osteoclasts. 



Hypertrophy of Bone. 



What do you understand by hypertrophy of bone ? 



An increase in size of the bone without change in the 

 osseous structure. 



What forms of bone hypertrophy are recognized ? 



1. Exostosis : It represents a circumscribed hypertrophy. 

 This neoformation has no sharply defined boundaries, but 

 gradually merges into the osseous tissue from which it springs. 



2. Osteophyte : Also represents a circumscribed hyper- 

 trophy, being just as much the product of an ossifying 

 periostitis as the exostosis, but its boundaries are sharplj 

 defined and the osteophyte makes the impression as if it could 

 be readily separated from the bone from which tt springs. 



3. Hyperostosis : Represents a diffused hypertrophy ; ir 

 other words, a larger bone area is involved in the hypertrophic 

 change. 



4. Osteosclerosis: Represents a hypertrophy arising in th( 

 marrow of the bone, while those previously spoken of origi 

 nate in the periosteum. 



