IV.— MALIGNANT TUMOURS IN ANIMALS. 

 By MM. Cadiot, Gilbert, and Roger. 



Animals frequently suffer from tumours similar to those affecting 

 man. The occurrence of such lesions was recognised by the oldest 

 authors who devoted their attention to animal pathology. They are 

 mentioned in the writings of the Greeks and Latins, and in the works 

 of the Hippiatres, but the merit of having first given exact descriptions 

 of some of them, and of having shown their frequency in carnivora — 

 especially in the dog — must be ascribed to Huzard in the eighteenth 

 century. 



From 1825, when the first French veterinary medical journals 

 appeared, the question was studied by a large number of observers, 

 among whom may be mentioned Trousseau and U. Leblanc, Gerlach, 

 C. Leblanc, Trasbot, and Plicque. 



At the present day we know that cancer may occur in all species of 

 animals. The fact that it has seldom been noted in the goat and 

 sheep is undoubtedly due to neglect of the pathology of these animals ; 

 what is true of tuberculosis probably applies also to cancer ; cases will 

 be found if trouble is taken to look for them. 



Among the domestic animals the dog is most frequently affected 

 with new growths, then the hor.se, and afterwards the cat, ox, and pig. 

 In birds, tumours are not uncommon, but many show special histo- 

 logical characters. 



etiology and Pathogeny. — In animals the aetiology of tumours is as 

 obscure as in man. The influence of heredity seems established by 

 several cases. We saw a bitch which had twice been operated on at 

 intervals of a year for cancer of the mammary gland. Two of her 

 progeny were also attacked with mammary cancer, one when four 

 years old, and the other when five, that is, at ages when epithelial new 

 growths are somewhat rare. 



Age plays an important part as a predisposing cause. Of thirty- 

 three cases in the dog, in which the age was exactly known, the figures 

 were as follows : — one case at three years ; one at four years ; two at 

 five years ; four at six years ; nine at seven to eight years ; eight at 



