316 PRINCIPLES OF VETERINARY SURGERY 



In time the tint of the ecchymotic skin changes to green or 

 black. But this transformation, though very important in 

 human medicine, is too trifling an issue in veterinary path- 

 ology to warrant the discussion of the theories advanced in 

 explanation of the cause of these color changes. 



2. Contusions of the Second Degree. — Blood tumors. — 

 A more violent blow causes an ecchymosis, as in the pre- 

 ceding variety, but in addition there is a cavity filled with 

 bruised tissue, serosity and blood. The skin is raised by the 

 accumulated liquid in the injured focus and a swelling re- 

 sults. When the blood accumulates on a resisting surface, 

 as bone, the swelling is designated as a sanguineous tumor, 

 (blood tumor) and when formed in the soft tissues it is 

 called a sanguineous sac (blood sac). A distinction may, 

 therefore, be made between the two expressions. 



The sanguineous tumor may be very large, and yet pro- 

 duce no lameness. The rapidity of its formation and the 

 sensation of crepitation felt on palpation are sufFtciently 

 characteristic. The crepitation is distinguished from that of 

 fracture by the harshness of the latter. It is soft and reap- 

 pears with each formation of the coagula. 



The sanguineous accumulations may become complicated 

 with suppuration and gangrene. The former is not rare 

 among debilitated animals or those under the bane of a mi- 

 crobian affection. A sanguineous sac nearly always suppu- 

 rates in the horse afflicted with strangles, or in a dog suffer- 

 ing from distemper. The injured point is weakened and the 

 micro-organisms circulating in the blood find an excellent 

 environment for growth. 



Pathological Anatomy. — The blood that flows after 

 the blow pushes the tissues apart and thus creates a 

 cavity for itself, which becomes lined with fibrinous deposits, 

 and soon a genuine sac is found to be established. These 

 imrnediate phenomena are accompanied by the work of or- 



