Application of active kidney injury biomarkers to predict kidney involvement in canine urinary tract infection

Pyelyonephritis can complicate lower urinary tract infection (UTI) but often is difficult to definitively document. The active kidney injury biomarkers, urinary clusterin (uclust) and urinary cystatin-B (ucyst-B), have potential to identify kidney involvement in dogs with UTI. The association of uclust and ucyst-B with bladder urine, bladder wall, and ureteral urine culture results were evaluated in 4 client-owned dogs undergoing cystoscopy for urinary incontinence. Urine from the bladder (cystocentesis), both ureters (collected using guarded catheters), and bladder wall (biopsy) were cultured; and urine specimens were assayed for biomarkers at IDEXX reference laboratories. Urine and bladder wall cultures were scored as positive (+) or negative (−) for bacterial growth. Uclust and ucyst-B were scored as positive (+) or negative (−) for concentrations above or within the reference intervals, respectively. (Table 1)Ucyst-B demonstrated kidney injury in 3/3 dogs with UTI and one dog with a - urine culture but + bladder wall and ureteral cultures. Ucyst-B was + in 5/8 ureteral collections with + growth and 2/8 with – growth. Uclust was poorly associated with + bladder or ureteral cultures. These preliminary results suggest ucyst-B may help identify kidney infection or active injury in dogs with UTI.