Survival of dogs with pituitary-dependent hyperadrenocorticism treated twice daily with low doses of trilostane.

Abstract

Twice daily low trilostane doses have proven to be effective to manage canine Cushing's syndrome. However, survival and prognostic factors in dogs treated with this protocol have not been evaluated. The aim of the study was to evaluate survival and prognostic factors, including systolic blood pressure (SBP) at diagnosis, in dogs with pituitary-dependent hypercortisolism (PDH) treated with low trilostane doses. Medical records of 91 dogs newly diagnosed with PDH initially treated with 0.2-1.1mg/kg of trilostane twice daily were retrospectively included. Survival times were calculated using the Kaplan-Meier estimator. Univariable and multivariable analysis were performed using the Cox proportional hazard regression analysis. Overall, median survival was 998 days (range 26-1832 days, 95% confidence interval=755-1241 days). In the multivariable analysis, age (hazard ratio [HR]=1.337, p<0.001), presence of calcinosis cutis (HR=5.271, p<0.001), body condition score (BCS) ≤3/9 (HR=8.100, p<0.001) and higher platelet count (HR=1.002, p=0.022) were negatively correlated with survival. SBP was not associated with survival. Low-dose trilostane treatment twice daily provides slightly longer survival than previously reported for dogs with PDH treated once or twice daily at higher doses. Older age, presence of calcinosis cutis, low BCS and higher platelet count, but not systemic hypertension, are predictive of poorer prognosis in dogs with PDH.