Neoplasms 383 



ington showing primary adeno-carcinoma of the mamma with 

 secondary growth in the liver and spleen. 



The carcinomata are notable on account of their rapid growth, 

 but curiously enough, they may remain quiescent after attaining a 

 certain degree of development. Strong proof of carcinomatous 

 character is the progressive extension of a tumor to adjacent tissues. 

 Regional extension takes place through lymphatics with which they 

 are abundantly supplied, while general dissemination mostly takes 

 place through the venous system through perforation of a vein- 

 wall by carcinoma cells. Dissemination is less frequent in epithe- 

 lioma than in malignant adenoma. 



Adult animals are the principal sufferers, and the average age 

 is in the neighborhood of eight years. Froehner based some 

 statistics on sixty-five cases he had treated by surgical procedure, 

 as follows : 



Number of dogs affected. Aged. 



10 2—4 years. 



18 5 — 6 years. 



22 7 — 8 years. 



12 9-10 years. 



3 12-13 years. 



In a hundred observations on the part of Cadiot and Almy the 

 proportions were similar: 



Number of dogs affected. Aged. 



6 I — 3 years. 



18 3—5 years. 



33 6—9 years. 



26 9-12 years. 



14 12-15 years. 



3 15-20 years. 



In microscopic appearance, carcinomata vary according to their 

 situation and period of existence. A typical carcinoma as occur- 

 ring in the skin is a more or less uneven, indurated, and sensitive 

 growth with a metastatic tendency to infiltrate neighboring tissues. 

 It has a circumscribed edge and a raw, ulcerating, crater-Hke center, 

 from which an offensive discharge is emitted. Ulceration is often 

 absent, and instead, the surface has an irregular scarred appearance. 

 The tumor is freely mobile from the surrounding tissues but inti- 

 mately adherent to its cuticular covering. Its dimensions may vary 



