title: Evaluation of kidney injury in dogs with pyometra based on proteinuria, renal histomorphology, and urinary biomarkers.
abstract: BACKGROUND
  Proteinuria is a feature of pyometra-associated renal dysfunction, but its prevalence and clinical relevance are not well characterized.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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 B(2)) 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Pharmacology, Toxicology and Biochemistry, Ghent University, Merelbeke, Belgium. bert.maddens@ugent.be
authors.forename: B
authors.initials: B
authors.lastname: Maddens
authors.forename: R
authors.initials: R
authors.lastname: Heiene
authors.forename: P
authors.initials: P
authors.lastname: Smets
authors.forename: M
authors.initials: M
authors.lastname: Svensson
authors.forename: L
authors.initials: L
authors.lastname: Aresu
authors.forename: J
authors.initials: J
authors.lastname: van der Lugt
authors.forename: S
authors.initials: S
authors.lastname: Daminet
authors.forename: E
authors.initials: E
authors.lastname: Meyer
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000209:etiology / Q000473:pathology / Q000652:urine / Q000662:veterinary*; D000818:Animals; D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000652:urine; D004283:Dog Diseases / Q000175:diagnosis* / Q000473:pathology / Q000652:urine; D004285:Dogs; D005260:Female; D007668:Kidney / Q000473:pathology* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D008856:Microscopy, Fluorescence / Q000662:veterinary; D011446:Prospective Studies; D011507:Proteinuria / Q000175:diagnosis / Q000652:urine / Q000662:veterinary; D055112:Pyometra / Q000150:complications / Q000473:pathology / Q000662:veterinary*
chemical_list: D015415:Biomarkers; D003404:Creatinine