318 PRINCIPLES OF VETERINARY SURGERY 



They vary from the size of a hen's egg to that of an mfant's 

 head. They have a very thick wall and cause no elevation 

 of temperature. These tumefactions appear suddenly, and 

 in some cases without the possibility of determining their 

 cause. 



From falls, when the animal drags along the ground, 

 and from bruises of carriage wheels the skin is loosened, 

 and a copious accumulation of serum in the space is the re- 

 sult. Whence comes this serum? Different views have 

 been advanced on the subject. Morel-Lavalle thought it 

 flowed out of the vessels that were drawn out, like the heated 

 glass tube or the Bunsen burner. Granfelt opined that it 

 had its origin in the hypersecretion of the areolar tissue, and 

 finally Verneuil advanced the hypothesis of an interstitial 

 lymphangitis. Whatever is the origin, the accumulated liquid 

 is always of an amber color and faintly tinted with red by 

 the blood. 



The collection of serum is rapid. It increases rapidly 

 for a few days and then retains almost the same dimensions 

 indefinitely. The lesion is easily recognized. The location, 

 the rapidity of formation, the clearly perceptible fluctuations, 

 are its typical symptoms. It is scarcely possible to confound 

 serous effusions with sanguineous sacs, owing to the charac- 

 teristic crepitation of the latter, and which does not exist 

 in the former. 



The oleaginous effusions, described by Violet and Gavard, 

 result from a fall, the bite of a horse or a kick. They are 

 seen especially in the region of the stifle. Out of 34 cases 

 observed by Gavard lo were in the region of the patella, 16 

 on the carpus and 8 on the fetlock. Their formation is anal- 

 ogous to that of serous effusions. "They are either entirely 

 dormant, without any lesion of the skin, or else more or less 

 sensitive and ■ accompanied with an inflammatory obstruc- 

 tion which causes a lameness of variable intensity." They 



