Cortisol Concentrations in Well-Regulated Dogs with Hyperadrenocorticism Treated with Trilostane

Area of Science:

• Veterinary Medicine
• Endocrinology

Background:

• Hyperadrenocorticism in dogs often lacks clear treatment guidelines for well-regulated cases.
• Specific monitoring parameters for trilostane therapy are not well-defined.

Purpose of the Study:

• To compare serum cortisol levels from two ACTH stimulation tests in dogs with well-regulated hyperadrenocorticism.
• To evaluate if a later ACTH stimulation test influences cortisol concentration interpretation.

Main Methods:

• A prospective study involving thirteen dogs with clinically well-regulated hyperadrenocorticism.
• Two ACTH stimulation tests were performed on the same day: one 3-6 hours post-trilostane and a second 9-12 hours post-trilostane.
• Paired t-tests were used to compare cortisol concentrations.

Main Results:

• Cortisol levels before and after the first ACTH stimulation (3-6 hours post-trilostane) were significantly lower than those before and after the second stimulation (9-12 hours post-trilostane).
• Pre-stimulation cortisol levels at 3-6 hours were 1.4 ± 0.3 μg/dL, rising to 1.5 ± 0.3 μg/dL post-stimulation.
• Pre-stimulation cortisol levels at 9-12 hours were 3.3 ± 1.6 μg/dL, rising to 5.3 ± 2.4 μg/dL post-stimulation.

Conclusions:

• In dogs with well-regulated hyperadrenocorticism on trilostane, a later ACTH stimulation test may yield higher cortisol readings.
• These elevated cortisol levels could support the continuation of trilostane therapy.
• The timing of ACTH stimulation tests is crucial for interpreting trilostane efficacy.