Adrenal cortex stimulation with hCG in spayed female dogs with Cushing's syndrome: Is the LH-dependent variant possible?

Background: The expression and overexpression of luteinizing hormone (LH) receptors in the canine adrenal gland cortex have been reported. Therefore, it was hypothesized that a LH-dependent form of Cushing's syndrome (CS) could exist in dogs. Aim: To assess whether the adrenal gland post-ovariectomy (OVx) exhibits a greater response to adrenocorticotrophin (ACTH) stimulation; to evaluate whether the adrenal gland responds to human chorionic gonadotropin (hCG) stimulation by increasing the release of cortisol; and to consider whether hCG stimulus testing would be useful as a diagnosis for possible cases of LH-dependent CS. Methods: Cortisol concentrations were measured from healthy female dogs (n=16) at baseline and following ACTH stimulation before and 2 months after gonadectomy (OVx). Cortisol concentrations were also measured for female dogs with CS ( Results: In normal female dogs, both pre- and post-stimulation cortisol concentrations increased following OVx ( Conclusion: Based on these results, an LH-dependent form of CS occurs in spayed female dogs, and that it is more likely to occur when female dogs are spayed later in life.