Efficacy of Trilostane Treatment in Reducing Proteinuria Secondary to Canine Spontaneous Hypercortisolism

Proteinuria is a common finding in dogs with spontaneous hypercortisolism (HC), occurring in 68–71% of untreated patients. The long-term impact of trilostane treatment on HC-associated proteinuria has been poorly documented. This retrospective, longitudinal, observational study aimed to assess the effect of trilostane treatment on HC-associated proteinuria.

The electronic database of a Veterinary Teaching Hospital was searched for dogs with HC in which proteinuria had been measured at the time of diagnosis and for which at least one follow-up evaluation was available. Dogs undergoing antiproteinuric therapy were excluded. For each patient, complete clinical, anamnestic, and analytical data at the time of diagnosis (T0) were retrieved. When available, clinical disease scores (assessed using a standardized questionnaire), daily trilostane dosage, blood pressure (BP), and urine protein-to-creatinine ratio (UPC) were recorded at T30 (30 days), T90, T180, and T365 after initiation of trilostane treatment.

At the last available follow-up, dogs were classified as “responders” (UPC reduction ≥ 50% from baseline) or “non-responders.” Possible differences in baseline clinical variables, including age, body weight, clinical score, UPC, BP, and daily trilostane dosage, were analyzed between the two groups. Additionally, median final clinical scores, median final BP, and median final daily trilostane dosage were compared between responders and non-responders.

Hypotheses regarding the onset of the antiproteinuric effect of trilostane and the lack of response observed in a subset of patients are discussed in the Discussion section.