Prognostic role of the product of serum calcium and phosphorus concentrations in dogs with chronic kidney disease: 31 cases (2008-2010).

Objective: To investigate serum calcium-phosphorus concentration product (sCaPP) as a predictor of mortality rate in dogs with chronic kidney disease (CKD).

Design: Retrospective case-control study.

Animals: 31 dogs with definitive CKD and 35 apparently healthy dogs.

Procedures: All dogs had been referred for nephrological consultation between December 2008 and December 2010. Dogs with CKD had stable disease for ≥ 3 months. On the basis of glomerular filtration rate < 60 mL/min/m(2), 13 of the 35 apparently healthy dogs were subsequently classified as having early CKD. Disease stage among dogs was determined on the basis of plasma creatinine concentration as follows: stage 1, < 123.7 μmol/L (n = 13), stage 2, 123.7 to 176.8 μmol/L (7); stage 3, 185.6 to 442 μmol/L (13); or stage 4, > 442 μmol/L (11). For each dog, serum concentrations of ionized and total calcium and phosphorus were evaluated once; the latter 2 variables were used to determine sCaPP.

Results: The sCaPP differed significantly between the 22 healthy dogs and dogs with stage 3 or stage 4 CKD. The proportion of dogs with sCaPP > 70 mg(2)/dL(2) increased with stage of disease. Mortality rate among the 24 dogs with sCaPP > 70 mg(2)/dL(2) was higher than that among the 42 dogs with sCaPP ≤ 70 mg(2)/dL(2). Dogs with sCaPP > 70 mg(2)/dL(2) had a comparatively lower survival rate, and risk of death was 4.2 times as high as risk for dogs with sCaPP ≤ 70 mg(2)/dL(2).

Conclusions And Clinical Relevance: For dogs with CKD, sCaPP > 70 mg(2)/dL(2) appeared to be a negative prognostic indicator, which was not influenced by the concomitant serum concentrations of phosphorus and total or ionized calcium.