222 DISEASES OF THE KIDNEYS 



Etiology. — This form of nephritis usually develops from 

 the acute parenchymatous, the causes of which have been 

 given. In the horse it may have an embolic origin emanat- 

 ing from the worm aneurysm in the anterior mesenteric 

 trunk. In cattle it sometimes results from pyelitis. In 

 man, sclerosis of the arteries is a common cause. 



Symptoms. — The principal symptom of chronic interstitial 

 nephritis, contrary to the acute and chronic parenchyma- 

 tous nephritis, is an increase in the quantity of urine voided 

 by the patient (polyuria). The urine is of low specific 

 gravity (1001 to 1010) and contains little albumin, few 

 tube casts and renal epithelium. Generally associated with 

 the polyuria are symptoms of hypertrophy of the heart 

 (see this), which is later followed by dilatation of the organ, 

 leading to symptoms of dropsy, such as anasarca, hydro- 

 thorax, hydropericardium and ascites. In some cases 

 uremia may follow with convulsions and coma. In rare 

 instances blindness results from albuminuria retinitis. 



Prognosis. — The prognosis is bad as the condition is gen- 

 erally incurable. As the efficiency of the patient (horses) 

 falls below the cost of keeping, many of them are destroyed 

 or traded off. 



Treatment. — While in man a palliative treatment which 

 will prolong life is indicated (nitroglycerin, digitalis, strych- 

 nin) in animals this does not pay. Otherwise the treatment 

 is the same as for acute parenchymatous nephritis. 



Purulent Nephritis. — Definition. — A suppurative inflamma- 

 tion of the kidneys leading to diffuse pus infiltration or to 

 abscess formation in the organ. 



Occurrence. — This form of nephritis is usually secondary 

 to such diseases as strangles, pyemia, wound infections, etc. 



Etiology. — ^The causes are pus-producing bacteria which 

 are carried to the kidney either through the blood or come 

 from the bladder or pelvis of the kidney through the urine. 

 Specifically staphylococci and streptococci are the principal 

 causes. These bacteria produce in the organ either a dis- 

 seminated, purulent nephritis in the form of large numbers 

 of small abscesses, found principally in the cortex (nephritis 

 punctata), or a few isolated large abscesses (pyonephrosis). 



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