262 MANUAL OF EQUINE MEDICINE. 



The causes of renal haemorrhage may be arranged in two 

 classes : 



1. Local pathological lesions, viz., 



(a) Those due to congestion orinflammation of the kidneys. 

 (5) Cancerous or melanotic growths, or the presence of 

 calculi in the kidney. 



2. Symptomatic causes, or those depending upon some 

 general or constitutional disease. 



Blood-casts, or moulds of the uriniferous tubes formed by 

 the coagulation of the blood in their lumina, are not un- 

 commonly found in the urine in cases of renal haemorrhage. 



Blood in the urine may be detected by the presence of 

 the red corpuscles seen in it when examined microscopicall}^. 



The appearance of the cells varies somewhat according 

 to the specific gravity of the urine ; if it be high, the cells 

 are small and shrivelled; if it be low, they are large, trans- 

 parent, and circular. 



The urine may also be tested by the addition of a drop 

 or two of tincture of guaiacum and a few drops of ozonized 

 ether to a small portion in a test-tube, when, if blood- 

 pigment be present, the ether which collects at the top will 

 be coloured blue. 



Urine containing blood is of necessity albuminous. 



Albumen. — The presence of albumen in the urine in any 

 quantity is of pathological significance. It may be found in 

 the urine from structural changes in the kidney in renal 

 congestion, or may be due to the presence of blood or pus. 



Albumen, when present, may readily be detected. 



If the urine be alkaline, as it frequently is, it is first 

 necessary in testing it to add a few drops of acetic acid to 

 a small portion in a test-tube, in order to slightly acidify it. 

 After this the urine should be boiled, when, if albumen be 

 present, it will be coagulated, forming opaque flakes, which 

 gradually subside to the bottom of the tube. 



