Efficacy of Transsphenoidal Hypophysectomy in Treatment of Dogs with Pituitary-Dependent Hyperadrenocorticism

Abstract

The long-term survival, disease-free fractions, and the complications of hypophysectomy in 150 dogs with pituitary-dependent hyperadrenocorticism (PDH) were examined in a prospective study. Long-term survival and disease-free fractions in relation to pituitary size were analyzed by the Kaplan-Meijer estimate procedure. The 1-, 2-, 3-, and 4-year estimated survival rates were 84% (95% confidence interval [CI], 76-89%), 76% (67-83%), 72% (62-79%), and 68% (55-77%), respectively. Treatment failures included procedure-related mortalities (12 dogs) and incomplete hypophysectomies (9 dogs). The 1-, 2-, 3-, and 4-year estimated relapse-free fractions were 88% (CI: 80-93%), 75% (64-83%), 66% (54-76%), and 58% (45-70%), respectively. Postoperative reduction of tear production (58 eyes in 47 dogs) was often reversible but remained low until death in 11 eyes of 10 dogs. Central diabetes insipidus (CDI) occurred more frequently (62%) in dogs with enlarged pituitaries than in dogs with nonenlarged pituitaries (44%). Survival and disease-free fractions after hypophysectomy were markedly higher in dogs with nonenlarged pituitaries than in dogs with enlarged pituitaries. Transsphenoidal hypophysectomy is an effective treatment for PDH in dogs. The survival and disease-free fractions after hypophysectomy decrease and the incidence of CDI increases with increasing pituitary size. Therefore, early diagnosis of PDH is important and transsphenoidal hypophysectomy is expected to have the best outcome when used as primary treatment for dogs with nonenlarged or moderately enlarged pituitaries.

Lymphocytic Hypophysitis in a Dog with Diabetes Insipidus

“…In pituitary masses with suprasellar expansion, these nuclei may become compromised, possibly leading to diabetes insipidus. This may also occur after hypophysectomy (Hanson et al, 2005(Hanson et al, , 2007. Plasma ACTH concentration was moderately elevated in the present case, which may be a reflection of the acute systemic inflammatory phase of the disease before destruction of the adenohypophysis leads to complete pituitary insufficiency.…”

“…The most commonly encountered adenoma is the pituitary corticotroph adenoma that causes excess secretion of adrenocorticotropic hormone (ACTH) and results in pituitarydependent hypercortisolism (Cushing's-like disease) (Hanson et al, 2005). The pituitary somatotroph adenoma causes hypersecretion of growth hormone (GH) and results in acromegaly, but is rare in dogs (Fracassi et al, 2007).…”

New Treatment Modalities for Brain Tumors in Dogs and Cats

“…8,15 Transsphenoidal hypophysectomy has been demonstrated to be an effective surgical technique in dogs and cats with nonenlarged to moderately enlarged pituitary adenomas, with a reported 4-year survival rate of 68% in dogs. 16 Currently available surgical techniques often preclude safe resection of intraparenchymal tumors that are infiltrating the surrounding brain or intimately associated with critical neuroanatomic structures. There is little information available regarding the efficacy of or indications for surgery in canine and feline brain tumors other than meningiomas and pituitary tumors.…”

“…[12][13][14][15][16][17][18] Studies investigating treatment of a variety of presumptively diagnosed brain tumors in dogs with fractionated radiotherapy reported median survivals that range from approximately 300 to 700 days. 17,18 Dogs with meningiomas treated with 3-D conformal radiation therapy had an overall median survival of 577 days, and the median survival increased to nearly 30 months (ie, approximately 900 days) when dogs dying of causes other than meningioma were excluded.…”

“…However, both surgery and radiotherapy can be associated with treatment-associated morbidity, and local treatment failures after these therapies remain a common cause of death or euthanasia. [12][13][14][15][16][17] Surgical treatment has been best described for forebrain meningiomas, which is the most common primary brain tumor type in both dogs and cats. 8,[12][13][14][15] In dogs with meningiomas, the reported median survival after traditional surgical resection is approximately 7 months.…”