Pituitary metastasis of pancreatic origin in a dog presenting with acute-onset blindness.

Pituitary metastases have rarely been recorded in dogs, and to date, none of those reported have been of pancreatic origin. MRI findings are available for only one of those cases. Herein the authors present an 11 yr old English springer spaniel diagnosed with pituitary metastasis of pancreatic origin with a 24 hr history of blindness and only a single lesion on MRI. Neurologic and ophthalmologic examinations localized the lesion to the optic nerves, optic tracts, or optic chiasm. MRI showed a single lesion characterized by a well-circumscribed pituitary mass with extrasellar extension, causing compression of the optic chiasm. Signal intensity was unusual as enhancement could not be appreciated after contrast administration. The dog was euthanized without further diagnostic tests. Histopathologic examination revealed a poorly differentiated exocrine pancreatic carcinoma with widespread metastasis involving the pituitary gland. To the authors' knowledge, this is the first such case reported in a dog. Pituitary metastases should be included as a differential diagnosis for dogs presenting with acute-onset blindness and for single brain masses affecting the pituitary gland.