*These authors share senior co-authorship.
Evaluation of Kidney Injury in Dogs with Pyometra Based on Proteinuria, Renal Histomorphology, and Urinary Biomarkers
Article first published online: 16 AUG 2011
Copyright © 2011 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 25, Issue 5, pages 1075–1083, September/October 2011
How to Cite
Maddens, B., Heiene, R., Smets, P., Svensson, M., Aresu, L., van der Lugt, J., Daminet, S. and Meyer, E. (2011), Evaluation of Kidney Injury in Dogs with Pyometra Based on Proteinuria, Renal Histomorphology, and Urinary Biomarkers. Journal of Veterinary Internal Medicine, 25: 1075–1083. doi: 10.1111/j.1939-1676.2011.0772.x
van der Lugt is presently affiliated with Vet Med Labor, IDEXX Laboratories, Mörikestrasse 28/3, 71636 Ludwigsburg, Germany. Part of this work was presented as an abstract at the annual ECVIM-CA congress in Toulouse, France, September 9–11, 2010.
- Issue published online: 20 SEP 2011
- Article first published online: 16 AUG 2011
- Submitted December 13, 2010; Revised May 25, 2011; Accepted June 24, 2011.
- Chronic kidney disease;
- Focal segmental glomerulosclerosis
Background: Proteinuria is a feature of pyometra-associated renal dysfunction, but its prevalence and clinical relevance are not well characterized.
Objectives: To define which subset of dogs with pyometra has clinically relevant kidney injury by quantification of proteinuria; light, immunofluorescence, and electron microscopic examination of kidney biopsy specimens; and measurement of urinary biomarkers.
Animals: Forty-seven dogs with pyometra. Ten clinically healthy intact bitches of comparable age.
Methods: Prospective study. Routine clinicopathological variables including urinary protein to creatinine ratio (UPC) were analyzed. Validated assays were used to quantify urinary biomarkers for glomerular (urinary albumin, urinary immunoglobulin G, urinary C-reactive protein, urinary thromboxane B2) and tubular function (urinary retinol-binding protein, urinary N-acetyl-β-d-glucosaminidase). Kidney biopsy specimens from 10 dogs with pyometra and dipstick urine protein concentrations of 2+ or 3+ were collected during ovariohysterectomy. Urinalysis was repeated within 3 weeks after surgery in 9 of the 10 dogs.
Results: UPC (median, range) was significantly higher in dogs with pyometra (0.48, 0.05–8.69) compared with healthy bitches (0.08, 0.02–0.16) (P < .01). Twenty-two of 47 dogs with pyometra had UPC>0.5, 12 had UPC>1.0, and 7 had UPC>2.0. Glomerulosclerosis and tubulointerstitial nephritis were common kidney biopsy findings in proteinuric dogs with pyometra. Dogs with glomerulosclerosis (5/10), either global or focal and segmental, had UPC>1.0 at ovariohysterectomy and afterward. Dogs with structural glomerular and tubular changes mostly had urinary biomarker to creatinine ratios above the 75th percentile.
Conclusion: Dogs with pyometra and UPC>1.0 or high ratios of urinary biomarkers appear likely to have clinically relevant renal histologic lesions and require monitoring after ovariohysterectomy. Future studies should evaluate the role of pyometra-associated pathogenic mechanisms in causing or exacerbating focal and segmental glomerulosclerosis in dogs.