Efficacy of Transsphenoidal Surgery on Endocrinological Status and Serum Chemistry Parameters in Dogs with Cushings Disease

Postoperative changes in the endocrinological status and serum chemistry during the 4 years after transsphenoidal surgery (TSS) in 25 dogs with Cushings disease were investigated in a prospective study. In all 25 dogs, Cushings disease was diagnosed from resected pituitary tissues as a corticotroph adenoma in the anterior lobe of the pituitary. Prior to TSS, all 25 dogs showed hypercortisolemia. After TSS, ACTH-stimulation test showed continued low serum cortisol concentrations in 21 dogs (84%). In addition, serum thyroid stimulating hormone concentrations decreased sequentially, while serum T4 concentrations tended to increase from the postoperative hormone substitution therapy to avoid secondary hypothyroidism. In regard to serum chemistry, alkaline phosphatase (ALP), alanine aminotransferase (ALT), and total cholesterol are commonly increased in canine Cushings disease. In this study, ALP, ALT, and total cholesterol were also increased in 23 cases (92%), 19 cases (76%), and 20 cases (80%), respectively. However, postoperatively, those concentrations gradually decreased. The postoperative serum concentrations of ALP at 1 year, that of ALT at six months to 2 years, and that of total cholesterol during the 4 years decreased significantly compared to the concentrations before TSS. These results show that TSS is an effective treatment for canine Cushings disease and for the long-term improvement of hypercortisolemia. Moreover, TSS is effective in the improvement of hypercortisolism, such as increased concentrations of serum ALP, ALT, and total cholesterol.