302 PBINCIPLES OF VETEBINABY SUEGEEY 



diately surrounding a suppurative focus (for instance, aa 

 abscess). 



What are the symptoms of inflammatory edema ? 



The diseased section is swollen, its overlying cutaneous 

 covering is tense, hot and painful. 



What is a stasis edema ? 



A dropsical state of the lymph spaces of the cutis and sub- 

 cutis due to an obstruction of the venous or lymphatic circu- 

 lation. 



How is stasis edem,a explained f 



The return flow of the blood may be variously interfered 

 with. Lowered vitality due to debilitating diseases, old age,, 

 weak heart, want of exercise, chronic heart, lung, kidney,, 

 liver and blood diseases all have a tendency to produce cer- 

 tain changes in the endothelial lining of the walls of th& 

 blood vessels, as a result of which liquid and corpuscular ele- 

 ments can leak from the vessel holding them. Pathologists 

 generally agree that injury to the endothelial cells and cement 

 substance between these cells are the most important factors 

 in allowing a transudation to take place — supported, of course, 

 by intravascular pressure and anything interfering with 

 the free flow of the blood. An obstruction to the lymphatia 

 circulation in itself rarely produces a stasis edema, because 

 lymph vessels anastomose too freely, but they assist in the 

 production of passive edema whenever the demands made 

 ■upon them are greater than their capacity for work ; in other 

 words, the lymph spaces, instead of being continuously and 

 regularly emptied, remain filled with the transudate. 



What are common examples of stasis edema in aniTnals ? 

 In the horse, stocking of the hindlegs, even of the sheath» 



