Effects of Oral Prednisone Administration on Serum Cystatin C in Dogs

BACKGROUND: Oral administration of glucocorticoid alters serum cystatin C (sCysC) concentration in humans. OBJECTIVE: To determine if oral administration of prednisone alters sCysC in dogs without pre‐existing renal disease. ANIMALS: Forty six dogs were included: 10 dogs diagnosed with steroid responsive meningitis arteritis (SRMA; group A), 20 dogs diagnosed of pituitary‐dependent hyperadrenocorticism (PDH; group B), and 16 healthy control dogs (group C). METHODS: Retrospective observational study. SRMA diagnosed dogs were administered prednisone 4 mg/kg/24 h PO 7 days, reducing the dose to 2 mg/kg/24 h 7 days before medication withdrawal. In group A, sampling was performed at days 0, 7, 14 and a final control at day 21. Blood and urine samples were collected in the 3 groups, and in group A, sampling was performed at all time points (days 1, 7, 14, and 21). RESULTS: In group A, sCysC was significantly higher at day 7 compared to the control group (0.4 ± 0.04 mg/L vs. 0.18 ± 0.03 mg/L mean ± SEM respectively P < 0.01); sCysC values decreased to basal at day 14 when the dose was decreased and after 1 week of withdrawal of prednisone (0.27 ± 0.03 mg/L for group A at day 14 and 0.15 ± 0.02 mg/L at day 21; P > 0.05). Dogs with PDH included in group B did not have significant differences in sCysC (0.22 ± 0.03 mg/L) compared to control (P > 0.05). CONCLUSIONS AND CLINICAL IMPORTANCE: Oral administration of prednisone unlike altered endogenous glucocorticoid production, increases sCysC in dogs in a dose‐dependent fashion.