Renal dysfunction in dogs with pyometra.

Renal function and pathologic changes in 27 dogs with pyometra were studied. Evaluation included CBC; serum biochemical evaluation; urinalysis; urine and uterine bacteriologic culture; uterine morphologic features; and light, electron, and immunofluorescent microscopic evaluation of renal tissues. Measurements of 24-hour creatinine clearance, protein excretion, Na excretion, and urine volume were made in 12 dogs without azotemia. Of 27 dogs, 26% were azotemic and 89% had a urine sp gr less than 1.035. Glomerular filtration rate was reduced in 75% of 12 dogs without azotemia. None of these 12 dogs was proteinuric. Examination of renal biopsy specimens revealed a high prevalence of mild tubulointerstitial nephritis, but few specific glomerular lesions. Minimal immunofluorescence was detected within the mesangium in 18% of the dogs. Immunofluorescence was not associated with the interstitium or tubules. Urinary tract infection was detected in 22% of the dogs. Escherichia coli and Klebsiella were recovered from the uterus in 59 and 15% of the dogs, respectively. Low urine specific gravity values were obtained from dogs without azotemia and from dogs with uterine cultures considered negative for E coli and other gram-negative bacteria. The reduction in glomerular filtration rate was a functional abnormality not correlated with structural damage in the glomerulus.