CIRCl'LAR UISTURIJANCKS. 



119 



external pressure hinder the passage of lymph and hence favor 

 its^ accumulation. As the anastomoses of lymph channels is 

 quite complete the obstruction of the outflow of lymph is a 

 minor cause. 



Varieties of oedema according to location are as follows:— 



Fig. SO. — Dog with Ascites, a result of an licpatic tumo 



Ascites: an abnormal accumulation of an oedematous fluid 

 in the peritoneal cavity usually residting from obstructed portal 

 circulation. 



Hydrothorax, and abnormal accumulation of oedematou.'^ fluid 

 in the pleural cavity or cavities. It is usually unilateral in the 

 horse and is caused by obstruction of the internal thoracic vein. 



H\dropcriccirdiuin ; and abnormal accumulation of oedematuus 

 fluid in the pericardial sac. This variety is very rare as a 

 primary condition. It is caused from venous obstruction of 

 cardiac vessels or vessels of the cardiac sac. 



Hxdrocclc: an abnormal accumulation of an oedematous 

 fluid within the vaginal tunic, e. g., the so called "water seed", 

 caused by adhesion of the vaginal tunic in the inguinal canal 

 which is usually the result of improper castration. 



Hxdrocephalus: an abnormal accumulation of oedematous 

 fluid in the serous cavities of the brain or its meninges caused 

 bv venous hyperemia. Thus external hydrocephalus is an 



