Trilostane is reported to be effective in about 90% of dogs with spontaneous hypercortisolism. Factors able to predict trilostane efficacy have never been evaluated. This retrospective study aimed to compare different clinical, ultrasonographic (US), and clinicopathological findings between dogs with a good clinical response and dogs showing poor response to trilostane treatment.

Only dogs with pituitary-dependent hypercortisolism (PDH), diagnosed and monitored at a referral veterinary hospital and treated with trilostane twice daily, were included. Good responder dogs (GRD) were included if, after 6 months of treatment, they were receiving a trilostane dose lower than 3 mg/Kg BID, and all the clinical signs resolved. Poor responder dogs (PRD) were included if, after 6 months of treatment, they were receiving a trilostane dose higher than 3 mg/Kg BID and the clinical signs [polyuria and polydipsia (PU/PD) and dermatological signs] were still present. Clinical, ultrasonographic, and clinicopathological findings were compared between the 2 groups at diagnosis (T0) and after 6 months of treatment (T6).

Fourteen GRD and 17 PRD were included. Among the clinical signs, alopecia was the only clinical finding more significantly observed in PRD at the time of diagnosis (p<0.001). In GRD the following clinicopathological variables resulted significantly lower at T0 compared to the PRD: serum ALT (p=0.02), serum GGT (p=0.02), endogenous plasma ACTH (p=0.003), pre-ACTH serum cortisol (p<0.001), post-ACTH serum cortisol (p=0.02), 8 hours post dexamethasone serum cortisol (p=0.03). Serum creatinine was significantly higher in GRD (p=0.007). The number of GRD without bilateral symmetrical adrenomegaly on US was significantly higher compared to PRD (p<0.001). In GRD the following serum clinicopathological variables resulted significantly lower at T6 compared to PRD: ALT (p<0.001), GGT (p=0.001), ALP (p=0.009), cholesterol (p=0.007), phosphate (p=0.002), pre-ACTH cortisol (p<0.001), post-ACTH cortisol (p=0.006), pre-trilostane cortisol (p=0.008). Serum creatinine was significantly higher (p<0.001) in GRD (p=0.01).

In conclusion, this preliminary study showed that different routinely performed clinicopathological variables associated with some clinical and US findings might be useful to identify PRD. A larger population of dogs is needed to determine cutoff values and the predicting importance of these variables to early identify PRD.

Disclosures

Federico Fracassi: Financial support: Dechra, MSD Speaking and consultancies: Boehringer Ingelheim, Dechra, MSD, Royal Canin, Hill’s, Nestlé Purina, La Vallonea. Stefania Golinelli: Financial support: PhD scholarship funded by Dechra Speaking and consultancies: Dechra