PRINCIPLES OF VETERINARY SURGERY 347 



upon animals threatened with strangles may be followed by 

 an abscess formation. Firing, for example, may result in cu- 

 taneous suppurations. 



In the horse abscesses make their appearance in regions 

 most susceptible to injury,— the poll, the withers, the ac- 

 nestis, the buttocks, and the lower extremities of the limbs. 

 In the ox, horn-thrusts, blows, and bruises of the teats 

 are the most common efifective causes. Among milk cows 

 abscess occurs in the udder, three times in ten cases ; and in 

 the parotid region twice out of ten cases. Collections of pus 

 are also found with considerable frequency in the flanks, the 

 thigh, the shoulder, the costal region and the ischial region 

 In the goat abscesses are most frequent in the region of 

 the horns; in the hog, about the toe-nails, the lesions of 

 thrush being often their starting point. 



In the canine species collections of pus are encountered 

 more especially in the eyelids, the ears and the tail. In the 

 cat they are found in nearly every part of the body. 



Role of Micro-organisms. — The causes above enumerated 

 in the different species operate by bruising the tissues and 

 by provoking the formation of "points of least resistance," 

 but they also introduce at the same time the indispensable 

 element in the formation of every non-experimental abscess 

 — namely, the infection. 



The introduction of pyogenic micro-organisms into the 

 subcutaneous connective tissue, under usual conditions, is 

 promptly followed by a collection of pus at the seat of in- 

 oculation. The role played by the organisms in the genesis 

 of the abscess is therefore easily shown. Aseptic traumatism 

 brings negative results. Introduce aseptically a foreign asep- 

 tic body beneath the skin and no results will follow, but soil 

 it and abscess will be promptly evolved at the seat of the in- 

 flammation. Research, especially en the human body, has 

 shown that every idiopathic abscess contains a more or less 



