Transsphenoidal hypophysectomy as treatment for macro-adenomas in dogs: case series.

TRANSSPHENOIDAL HYPOPHYSECTOMY AS TREATMENT FOR MACRO-ADENOMAS IN THE DOG: CASE SERIES Pisoni L, Del Magno S, Foglia A, Fracassi F, Corradini S, Joechler M. Introduction Pituitary tumors can be classified according to the ratio between the pituitary height and the brain area (P/B value) with a cut-off of 0.31 mm-1 between micro and macroadenomas1. The aim of the study is to retrospectively review the surgical therapy and the related complications of the cases of transsphenoidal hypophysectomy in dogs with macroadenomas performed at the DIMEVET of the University of Bologna. Material and methods In the study dogs with a pituitary adenoma diagnosed by CT or MRI and treated surgically between 2011 and January 2015 were included. For transsphenoidal hypophysectomy all the dog were sedated with midazolam and fentanyl, the induction was executed with propofol and after oro-tracheal intubation, anesthesia was maintained by propofol in costant rate infusion and isolfuorane. Analgesia was provided by fentanyl. All the surgical procedures were performed according to the microsurgical technique described by Meij in 19972. In the post-operative period the dogs were monitored for neurological deterioration, electrolytes and fluid balance. Antibiotics, gastroprotection and opioids were administered. Hormonal supplementation consisted of desmopressin, corticosteroids and thyroxine. The histological evaluation of the masses removed was carried out. Results Seven dogs were included in the study and 8 surgeries were performed. The main represented breed was the Labrador Retriever (2/7 dogs), the median body weight was 34,5 kg, the median age was 7,5 years and 6/7 dogs were male. Of the 7 dogs included, 4 had pituitary-dependent hypercortisolism. One dog had hypopituitarism and 4 dogs showed severe neurological signs. All the 7 cases had an enlarged pituitary gland, the median P/B value was 0,8 mm-1 . In one dog the first surgical approach to the sphenoid bone resulted too caudal, in one dog there was a moderated bleeding during surgery and one dog had septic shock when recovered from anesthesia. In the post-operative period, complications were hypernatremia and hypertension (5/8 cases), neurological deterioration (4/8), exophthalmos (2/8), agitation (2/8) and venous thrombus (2/8), one in the splenic vein and one in the cranial vena cava. Four dogs were discharged, while 1 dog died due to sepsis and 3 dogs were euthanized for deterioration of clinical and neurological conditions. The histological diagnosis was adenoma in all cases. Discussion and conclusion Transsphenoidal hypophysectomy represents a solution to decrease the mass effect in enlarged pituitary adenomas, however better results were observed in microadenomas. A surgical learning curve is necessary for the surgeon. Nevertheless the complete removal of the mass is not always possible. In surgery the main difficulties were the exact locatization of the fossa hypophysalys and to recognize and completely remove the neoplastic tissue. All the cases presented had macroadenomas, some of them with very enlarged pituitary glands. In these dogs more complications were encountered in the post-operative period. Surgery represents a curative therapy, in cases of complete removal of the mass, both for the neurological signs and the eventual endocrinological disease. 1. Kooistra et al, J Endocrinol, 1997 2. Meij et al, Vet Surg, 1997