Serum cystatin C concentration measured routinely is a prognostic marker for renal disease in dogs.

This study examined the predictive value of serum cystatin C (Cys-C) concentration, measured during routine periodic health examinations, in the renal prognosis of dogs. A cohort of 140 dogs weighing <15 kg whose serum Cys-C concentrations were measured during periodic health examinations from December 2013 to March 2016 were prospectively studied, with renal disease-related death the predicted end point. Of the 140 dogs, nine died from renal diseases during the follow-up period (539 ± 249 days). Serum Cys-C concentrations were higher in the dogs that subsequently died of renal disease than in the censored group (0.8 ± 0.25 vs. 0.3 ± 0.1 mg/dl, respectively; P < .01). Dogs with high serum Cys-C concentrations (>0.55 mg/dl) had a shorter (P < .01) renal disease-specific survival period than those with low serum Cys-C concentrations (≤0.55 mg/dl). In conclusion, high serum Cys-C concentrations in periodic health examinations in dogs <15 kg predicted poorer prognosis for renal function.