Pituitary function and short-term clinical effects after transsphenoidal
hypophysectomy were investigated in clinically normal dogs. In study I, 8 dogs were given polyionic fluids IV during the first 12 hours after surgery. In study II, 4 dogs were given polyionic fluids IV and
glucocorticoid supplementation for 7 days. Pituitary function was assessed by evaluating basal
ACTH concentrations and results of a
growth hormone stimulation test before and 1 and 12 weeks after
hypophysectomy, an
ACTH stimulation test, a
thyrotropin-releasing hormone-stimulation test, and a modified water deprivation/
vasopressin response test before and 1, 4, 8, and 12 weeks after
hypophysectomy. Gross and histologic evaluations of the surgery site, thyroid and adrenal glands, and skin were done at 12 weeks after surgery. Four dogs from study I died within 27 hours after
hypophysectomy. Postmortem examinations of these dogs revealed liver and lung congestion compatible with
circulatory collapse. None of the dogs in study II died. For the surviving dogs in both studies,
diabetes insipidus developed immediately after
hypophysectomy and resolved within 2 weeks.
Hypernatremia also developed immediately after
hypophysectomy and resolved by 1 week. Production of
ACTH was evident at 1 and 12 weeks after
hypophysectomy in all dogs, and results of
ACTH stimulation tests after surgery were not notably different from results obtained before surgery. Results of
thyrotropin-releasing hormone stimulation and
growth hormone-stimulation tests supported the diagnosis of
hypothyroidism and hyposomatotropism attributable to
hypophysectomy. Histologic examination revealed thyroid
atrophy, epidermal and dermal
atrophy, and normal adrenal glands in all dogs and remnants of the hypophysis in 2 dogs from study I.(ABSTRACT TRUNCATED AT 250 WORDS)