TUMORS AFFECTING CATTLE. 315 



PARASITIC CYSTS. 



Parasitic "or foreign-body cysts, from the inflammatory reaction 

 induced by such parasites as the echinococcus (hydatid cyst) or by 

 the presence of various kinds of foreign bodies. 



EXTRAVASATION CYSTS. 



Extravasation cysts, caused by injuries which rupture blood ves- 

 sels, followed by an increase of fibrous tissue which forms a capsule 

 about the fluid. The hygromata in front of the knee in cattle, so- 

 called tumor of the knee, and serous cysts belong to this variety. 



Hygromata, or tumors of the knee. — These consist in the 

 simplest form of a collection of serous fluid mixed with fibrin within 

 a distended bursa. The walls surrounding the fluid become firm, 

 smooth, and dense. 



Outwardly the tumor appears fluctuating, though tense, while the 

 skjn which covers it may be normal, denuded of hair, or covered 

 with hard epidermal scales, possibly half an inch in thickness, form- 

 ing a hard, horny plate. The cavity which contains the fluid may 

 have the dimensions of a hen's egg, an apple, or a child's head. Its 

 walls are formed by the diseased secreting membrane of the bursal 

 sac, and are readily detachable from the subcutis of the skin. Their 

 internal surfaces are often uneven or supplied with projections or 

 tufted growths which support a fibrous network within the tumor. 



Tumors of the knee may also assume a granular type, as the result 

 of chronic inflammation or following operative or spontaneous evac- 

 uation of pus from the part. They are either firmly connected with 

 the skin or are detachable from it, and when laid open disclose a 

 whitish-red, porklike tissue surrounding a central nucleus of pus, or 

 a fistulous tract leading to the outer surface. They are caused by the 

 chronic inflammation which follows the bruises received by cattle in 

 lying down and in rising, or they may be due to falls on uneven, hard 

 ground. 



Treatrnjent for hygromata. — When the swelling first appears cold 

 water should be applied, followed later by bandaging with cloths 

 wrung out of warm water. If the swelling is soft, it should be punc- 

 tured at the lowest point, and afterwards the cavity should be 

 syringed with Lugol's solution. If the tumor is hard and nonfluctu- 

 ating, a mercurial blister may cause absorption and at the same time 

 prevent further injury to the part by making it more painful, thus 

 sparing it. 



Serous cysts. — These swellings are another variety of extravasa- 

 tion cysts, and are caused by such injuries as butting, running 

 against hard objects, and shipping ])juises, which are folloAved by an 

 outpouring of blood and lymph into the tissue spaces. These cysts 



