Update on Addison's Disease

By A.M. Oberbauer and T.R. Famula
Department of Animal Science, University of California, Davis

Summer, 2005

Addison’s disease, although treatable, can be a debilitating disorder for dogs as well as costly for the owner. In Addison’s disease, the adrenal cortex fails to synthesize and release adequate quantities of two classes of steroid hormones: those that regulate electrolyte balance (mineralocorticoids) and those that regulate many aspects of metabolism and the stress response (corticosteroids). We undertook a study to evaluate whether Addison’s is inherited in the Westie. It is purely a statistical question based upon information submitted by Westie owners. This information includes the health status (that is, whether the dog is Addisonian or not), pedigree data, and whether relatives are known to have health issues. In addition, we are collecting DNA for use in the second phase of the study. We receive on average thirteen Westies submitted per month. We have, thanks to the participation of Westie owners, 314 West Highland White Terriers in our database of which forty-one of are Addisonian. The number of submissions, while not optimal, was sufficient to begin to ask the question of how much does genetics contribute to the expression of Addison’s in the Westie. The data demonstrate that Addison’s is highly heritable in the Westie (heritability estimate in excess of 0.5 which indicates a large genetic component). To confirm this, and to begin the second phase of the study involving the generation of a genetic marker linked to Addison’s, we need additional participation by Westie owners. Please enroll dogs in the study by requesting participation kits at http://cgap.ucdavis.edu.