Adrenal sex hormone imbalance or congenital adrenal hyperplasia-like syndrome is a recently described disorder in dogs. The clinical signs are symmetrical alopecia and hyperpigmentation on the rump, perineum, caudal thighs, neck, tail and trunk, other areas being generally spared. Presentation is similar to the previously described growth hormone (GH) responsive alopecia and it is now thought that although decreased levels of GH may be a contributing factor, these are secondary to the sex hormone imbalance. The condition is thought to be due to a partial deficiency in glucocorticoid synthesis which results in the accumulation of the adrenal sex hormones that are precursors for these steroids. Unfortunately, such enzyme deficiencies have yet to be demonstrated in-vitro. Certain breeds are predisposed – Pomeranians and Chow Chows.

The pathophysiology of this presentation is somewhat controversial. Many of the previously described therapy responsive dermatopathies (GH responsive, castration response, Lysodren responsive, melatonin responsive etc) have very similar clinical presentations and perhaps their response to those therapies is non-specific. Realisation of these similarities has lead to the coining of the term “Alopecia X”.

Adrenal sex hormones are also useful in assessing male dogs who are attractive to other dogs (male and female).

Recent studies have suggested that some dogs with hyperadrenocorticism (particularly those with adrenal neoplasia) do not test positive by conventional ACTH stim. test, but will show elevated levels of sex hormones, including OHP. It is suggested these dogs are also tested using the SHAP profile.

In some cases, SHAP testing may also be used to help identify stress responses which give false positive ACTH stimulation test results. The OHP levels may be less affected than the cortisol levels. Less than 10% of dogs with hyperadrenocorticism would be expected to have post ACTH OHP values <4.5 nmol/L (Chapman et al, Veterinary Record, December 2003).