Trilostane Dose versus Body Weight in the Treatment of Naturally Occurring Pituitary‐Dependent Hyperadrenocorticism in Dogs

Background Trilostane is commonly used in the treatment of dogs with naturally occurring pituitary‐dependent hyperadrenocorticism ( PDH ). Dose recommendations have varied from the manufacturer and the literature. Hypothesis As body weight increases, dose/kg or dosage/day of trilostane required to control the clinical signs of PDH decreases. Animals 70 dogs with naturally occurring hyperadrenocorticism. Methods Retrospective study. Each dog must have been treated for at least 6 months and should have shown a “good response” to trilostane, as determined by owners. Statistical comparisons of dose and dosage were made after the dogs were separated into groups weighing <15 or >15 kg; groups weighing ≤10, 10.1–20, 20.1–30, and ≥30 kg; and then groups based on body surface area versus dose/kg and total amount of trilostane required to control the condition. Results There was no significant difference in trilostane dose in mg/kg of body weight or in the total amount of trilostane required daily to control clinical signs, except when the dose for dogs weighing >30 kg was compared with that for the other groups. However, despite lack of statistical significance when comparing groups, there was a significant trend using polynomial regression analysis, suggesting that as body weight increases, the amount of trilostane (mg/kg/dose as well as mg/kg/daily dosage) required to control clinical signs decreases. Conclusions and Clinical Importance Dogs weighing >30 kg, and possibly those weighing >15 kg, might require smaller amounts of trilostane per dose or per day than those weighing less, to control PDH ‐associated clinical signs.