Suspected pituitary apoplexy in a dog

Pituitary apoplexy is a syndrome attributed to sudden haemorrhagic necrosis of the pituitary gland, often secondary to pituitary neoplasia in people. A four-year-old male neutered Airedale Terrier was presented with a three-week history of lethargy and subsequently developed rapidly progressive neurologic signs of forebrain dysfunction. A contrast enhancing hypothalamic mass was shown on computed tomography. The dog developed severe hypernatraemia, isosthenuria and hypodypsia and was euthanased. A diagnosis of pituitary macroadenoma, with haemorrhage and necrosis, was made after post mortem examination. The abnormal pituitary tissue did not stain positively for ACTH antibody.