Pre‐trilostane and three‐hour post‐trilostane cortisol to monitor trilostane therapy in dogs

Abstract

It is recommended that trilostane therapy of canine hyperadrenocorticism is monitored using an ACTH stimulation test, however this has never been validated. Three cortisol concentrations (pre-trilostane, 3-hour posttrilostane and 1-hour post-ACTH stimulation) were compared to a clinical score obtained from an owner questionnaire. There were 110 sets of 3 cortisol measurements and questionnaires obtained from 67 trilostane treated dogs. Questionnaire results were used to classify each dog as well or unwell. Well dogs were then categorised as having excellent, moderate or poor hyperadrenocorticism control, using thresholds produced by 14 independent veterinarians. Correlation co-efficients were used to compare the three cortisol concentrations to the owner score and the Kruskal Wallis and Mann-Whitney U tests were used to compare the three cortisol concentrations between categories of control. Cortisol cut-off values between significantly different categories were determined using ROC curves. Pre-trilostane and 3-hour post-trilostane cortisol were better correlated to the owner score and had cut-offs to differentiate between categories of control that had superior sensitivity and specificity results, than the post-ACTH cortisol. Iatrogenic hypoadrenocorticism was not detected in any unwell dog. This study shows that the pre-trilostane and 3-hour post-trilostane cortisol are potentially better monitoring methods than the ACTH stimulation test.

The interpretive contribution of the baseline serum cortisol concentration of the ACTH stimulation test in the diagnosis of pituitary dependent hyperadrenocorticism in dogs

“…Therefore, it frequently is used as a screening test in the diagnosis of HAC. Furthermore, it is commonly used in monitoring response to treatment, in addition to newly introduced approaches employing BC for monitoring trilostane treatment . Current guidelines regarding the technical aspects of performing the ACTHST, including the latest ACVIM consensus statement on the diagnosis of spontaneous HAC, recommend collection of both baseline and post‐stimulation samples .…”

Comparison of two prepill cortisol concentrations in dogs with hypercortisolism treated with trilostane

“…In several studies baseline cortisol, endogenous ACTH, cortisol/ACTH ratio, haptoglobin, urine corticoid:creatinine ratio (UCCR) and clinical signs reported by owners were evaluated, but none of them seemed convincingly superior to the ACTH stimulation test [11–16]. A recent study compared the pre-trilostane cortisol, the three-hour post-trilostane cortisol and the post-ACTH cortisol concentrations against the clinical signs reported by owners [17]. This study showed that the pre-trilostane and the three-hour post trilostane cortisol concentrations were potentially better monitoring parameters than the post-ACTH cortisol concentrations, as they differentiated better between dogs with excellent control and dogs that were inadequately controlled [17].…”

“…A recent study compared the pre-trilostane cortisol, the three-hour post-trilostane cortisol and the post-ACTH cortisol concentrations against the clinical signs reported by owners [17]. This study showed that the pre-trilostane and the three-hour post trilostane cortisol concentrations were potentially better monitoring parameters than the post-ACTH cortisol concentrations, as they differentiated better between dogs with excellent control and dogs that were inadequately controlled [17]. In addition, a further study by the same group showed that the pre-trilostane cortisol concentration is more repeatable than the post-trilostane or the post-ACTH cortisol concentration in dogs on a constant dose of trilostane [18].…”

Effect of Intravenous or Perivascular Injection of Synthetic Adrenocorticotropic Hormone on Stimulation Test Results in Dogs

“…Several groups assessed sensitivity and specificity of a variety indices for confirming a diagnosis of Addison's disease without use of ACTHst . Other groups have evaluated non‐ACTHst indices as aids in trilostane management of dogs with HAC . Cost of ACTH is consistently mentioned as an indication for performing such studies.…”

“…Despite alternative approaches to diagnosis and monitoring that might avoid its use, the ACTHst remains a “test of choice” and is the test against which other diagnostic or monitoring protocols are often judged . Many veterinarians utilize the ACTHst whenever an owner allows, because results of this test continue to provide seemingly straightforward criteria for making a correct decision, whether regarding diagnosis or assessing response to therapy.…”