304 Surgical Diseases and Surgery of the Dog 



pain, and after attainment of a certain size, quiescence. The malig- 

 nant growths comprise sarcoma, carcinoma, and, as already stated, 

 mixed chondromata. They are distinguishable from the former 

 type by their more rapid growth, though they sometimes have 

 periods of quiescence, by extension to neighboring lymphatics, by 

 the pain and emaciation they induce, and by their tendency to ulce- 

 rate and undergo generalization. Either type must always be 

 carefully dififerentiated from inflammatory swellings and hernia, 

 particularly the inguinal variety (see Hernia). Hematoma resulting 

 from injury has been recorded by Rodet. 



Fibroma. This is a common form of mammary tumor. For- 

 merly much confusion existed as to its proper classification and it 

 was not infrequently confounded with adeno-fibroma. But, inas- 

 much as the essential element in a fibroma is fibrous tissue and this 

 type of growth develops as a pericanalicular fibrosis or proliferation 

 and projection of connective tissue round the glandular acini, it is 

 now recognized as pure fibroma. By this process of fibrosis groups 

 of acini become isolated, and these undergoing compression, lose 

 their glandular structure and appear as "islands" of cells. It was 

 these "islands" of cells which were once mistaken for true neoplastic 

 or adenomatous formations. 



Fibroma sometimes undergoes transformation into a myxo- 

 matous condition. 



Symptoms and Diagnosis. This growth develops as a hard, 

 knotty, mobile, and sharply-demarked swelling, varying in size from 

 a pigeon's egg to the human fist, but may attain very large dimen- 

 sions. The myxo-fibroma is considerably softer. 



Lipoma. The fat tumor occurs not uncommonly in plethoric 

 females. 



Symptoms and Diagnosis. In consistence it is soft and larda- 

 ceous. It grows slowly and is sharply demarked from the neigh- 

 boring tissue. 



Adenoma. True adenoma occasionally occurs in the gland and 

 is usually associated with more or less increased development of 

 fibrous tissue. Adeno-fibroma is the commonest type of growth met 

 with in this region. It may undergo progressive transition into 

 malignant carcinoma. Isolated or generalized cystic degeneration 

 is not at all uncommon. 



Symptoms and Diagnosis. In macroscopic appearance adenoma 

 is very similar to fibroma, and is hard to differentiate, but is some- 



