Hyponatremia as the Presenting Feature of a Pituitary Abscess in a Calf

A 2-month-old Simmental heifer presented for acute onset of neurological behavior. Laboratory tests confirmed the presence of hyponatremia, hypochloremia, and hypokalemia that improved with intravenous fluid therapy. Despite an initial cessation of neurological signs, symptoms re-emerged, and the heifer was euthanized due to poor prognosis. A pituitary abscess (Trueperella pyogenes) was observed on gross necropsy, suggesting that the effects of panhypopituitarism (inappropriate anti-diuretic hormone (ADH), adrenocorticotropic hormone (ACTH), and/or thyroid-stimulating hormone (TSH) secretion) may have resulted in the clinical findings. Pituitary abscess syndrome carries a poor prognosis due to the inability to penetrate the area with systemic antibiotic therapy. These findings highlight the unusual clinical presentations that may occur following pituitary abscess syndrome in cattle that practitioners need to consider when determining prognosis.