CONGESTION OF THE KIDNEYS. 



353 



tumors, or by the abnormal accumulation of food and gas in the 

 intestinal canal. Sometimes it is produced by thrombosis or com- 

 pression of the renal vein or artery (extension of a thrombus from 

 an aneurism of the great mesenteric). 



Pathological anatomy. In the two forms of congestion of 

 the kidney the latter is tumefied, softened, and colored a deep red. 

 In the active congestion especially, the kidney is infiltrated and 

 very soft (parenchymatous œdema) ; the surface of the organ is at 

 times cyanosed ; a slight traction exerted upon the capsule is suffi- 

 cient to detach it. Active hyperemia determines mainly the accu- 

 mulation of the blood in the vessels of the cortical substance ; the 

 passive, congestion in the veins of the medullar substance. 



When the passive congestion persists for a long time, the organ 

 takes a dark purple coloration, and the proliferation of the inter- 

 stitial connective tissue gives it a much firmer consistence (cyanosed 

 induration) ; at the same time the epithelium of the urinary canaliculi 

 is subject to regressive alterations ; it is affected by fatty degenera- 

 tion. These lesions may lead to hemorrhages and nephritis. 



Symptoms. In active renal hyperemia we observe polyuria ; 

 the urine is clear, transparent, its specific weight is diminished ; 

 its quantity may increase from five litres (a common normal amount 

 in the horse) to twenty-five litres and more ; its specific gravity, 

 which is 1040, may be lowered to 1005 or 1001 (polyuria is a form 

 of diabetes insipidus). The animals hold the back slightly arched, 

 the gait is stiff; no serious febrile reaction is to be observed. 



In passive congestion the quantity of urine is lessened and 

 albuminuria is present, often even hematuria; we find at times 

 hyaline cylinders in the urine. A certain weakness of the posterior 

 quarters may be observed. The affection is chronic and apyretic. 



Treatment. The active congestion must be combated by a 

 strong counter-irritant upon the intestine. 



The treatment of passive congestion is identical with that of 

 the causal disease. It is against this latter that active means 

 must be directed. 



Nephritis. 



The chapter on nephritis is the most incomplete of the entire 

 veterinary pathology. This weak point of our medicine depends 

 on two principal causes: the very short time during which the 

 practice of analyzing the urine of our animals has been in vogue, 



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