PART II 

 TUMORS OF THE GENITAL ORGANS 



The fundamental nature of tumors is essentially undeter- 

 mined. Clinically, many of the benign tumors of animals 

 bear strong evidences of transmissibility. They appear un- 

 expectedly in a stable or herd, or in a group of animals 

 within a herd, and involve simultaneously a large percentage 

 of the group. At present the general concensus of scientific 

 opinion appears to be that malign tumors are due to infec- 

 tion. Certain new-growths formerly regarded as true tu- 

 mors, like actinomycosis and botryomycosis, are now defi- 

 nitely classed as infections. In the dog, there occurs a 

 clearly defined venereal tumor definitely ascribed to infec- 

 tion, which is included among venereal infections instead of 

 among tumors. 



Chapter X 



A. MALIGNANT TUMORS 



1. Malignant Tumors of the Male Genitalia 



Herbivora, and especially ruminants, are apparently 

 highly resistant to malignant neoplasms. This may be ap- 

 parent only because most domestic ruminants are slaugh- 

 tered early in life for food. More than fifty per cent, of all 

 dairy calves born are slaughtered for veal. More than 

 ninety per cent, of male cattle of beef breeds are castrated 

 and are slaughtered at three to four years of age. The aver- 

 age age of dairy cows is below six years, though occasionally 

 they live to fifteen, eighteen or more. 



Malignant neoplasms affect chiefly adult or old animals. 

 Naturally it follows that they would be rare in species where 

 the technically normal duration of life is greatly abbreviated 

 by artificial means. 



Malignant neoplasms in domestic animals are most fre- 

 quent in dogs and horses, both of which are largely kept 



