Familial canine pituitary-dependent hyperadrenocorticism in wirehaired Dachshunds

Canine pituitary hyperadrenocorticism (Cushing's disease) caused by neoplasia of the corticotrope cells is one of the most common endocrine diseases especially in smaller dog breeds. Cushing's disease was diagnosed in eleven wire-haired Dachshunds and for further six wire-haired Dachshunds Cushing's disease was suspected on the basis of clinical signs. A joined pedigree could be ascertained for all these 17 dogs. Eleven of these dogs were so closely related to each other, that they were summarized in four nucleus families. Two fullsiblings were examined by means of clinical, laboratory diagnostic and morphological methods. The main lesions consisted of atrophic dermatosis with alopecia, increase of activity of liver enzymes in plasma and bilateral adrenocortical hyperplasia and therefore corresponded to the typical signs of a secondary hyperadrenocorticism. A rather unusual finding was the pituitary carcinoma in one of these dogs. Similarly to human patients affected by hyperadrenocorticism, real-time PCR analysis showed a 2.9-fold increase of expression of the canine MDR1 gene in the liver of one affected wirehaired Dachshund. This study documents the first familial occurrence of pituitary-dependent hyperadrenocorticism in wirehaired Dachshunds, the overexpression of the MDR1 gene in the dog and the third case of familial hyperadrenocorticism in dogs ever described.