Pituitary pars intermedia dysfunction with pituitary gland melanotroph adenoma in a Grevy’s zebra (Equus grevyi)

• Published in: Journal of Veterinary Medical Science 2024, Vol.86(1), pp.71-76
• Main Authors: TAKAHASHI, Naohiro, CHAMBERS, James K, OTA, Kaori, TODA, Kosuke, YOSHIMOTO, Yuto, MIYAJIMA, Umi, UCHIDA, Kazuyuki
• Format: Article
• Language: English
• Subjects: Adenoma; Adenoma - pathology; Adenoma - veterinary; Adrenocorticotropic hormone; Adrenocorticotropic Hormone - metabolism; Amyloid; Amyloid beta-Peptides; Animals; Atrophy; Brain tumors; Cerebrum; Endocrine disorders; Equidae; Equus grevyi; Female; Grevy’s zebra; Hyperglycemia; Hyperplasia; Hypertriglyceridemia; Immunoreactivity; Melanocyte-stimulating hormone; melanotroph adenoma; Melanotrophs - metabolism; Melanotrophs - pathology; Parenchyma; Pituitary; Pituitary Gland - metabolism; Pituitary Neoplasms - veterinary; pituitary pars intermedia dysfunction; Polydipsia; Polyuria; Tumor cells; Wildlife Science
• ISSN: 0916-7250; 1347-7439
• DOI: 10.1292/jvms.23-0177

A 22-year and 9-month-old female Grevy’s zebra (Equus grevyi) showed signs of polyuria, polydipsia, glucosuria, and muscle atrophy. Blood tests revealed hyperglycemia, hypertriglyceridemia, electrolyte imbalance, high levels of adrenocorticotropic hormone (ACTH) and cortisol, and low levels of hormones secreted by the pituitary pars distalis. Pathological examinations revealed a pituitary gland tumor and bilateral adrenal cortical hyperplasia. Pituitary tumor cells showed immunoreactivity for α-melanocyte-stimulating hormone and ACTH. The deposition of amyloid β was observed in the parenchyma and vascular walls of the cerebrum. The zebra showed clinical signs of pituitary pars intermedia dysfunction and was histopathologically diagnosed with pituitary gland melanotroph adenoma. This case report provides insight into neoplastic and endocrine diseases associated with the aging of a zebra.