Canine hypoadrenocorticism (Addison’s Disease) is due to a deficiency in production of corticosteroids and mineralocorticoids produced by the adrenal glands. These compounds are required for proper regulation of various pathways in the body including metabolism, blood pressure and response to stress. Affected dogs can present with a variety of non-specific clinical sighs including vomiting, diarrhea, lethargy, anorexia and weakness. Treatment for Addison’s is life-long and relatively expensive. Additionally, in the event of an Addisonian crisis, animals can die if they are not diagnosed and treated properly. Classically , as reported in the literature, it is a relatively uncommon endocrine disease affecting primarily middle-aged, female dogs of any breed. However, certain breeds including Nova Scotia Duck Tolling Retrievers (Tollers), Bearded Collies, Standard Poodles, Portuguese Water Dogs and Leonbergers appear to be at increased risk for developing Addison’s Disease. The purpose of this study is to perform a 10cM genome scan to identify genomic regions linked to Addison’s disease in Tollers. Ultimately, the goal of this research program is to develop a genetic assay to assist breeders in eradicating this costly and life-threatening disease. The results of this study will be made available to the Toller breed clubs for use in counseling breeders.