# Pituitary abscess, plexus-choroiditis and encephalitis by Helcococcus ovis in a calf

## TL;DR

A calf developed a pituitary abscess caused by Helcococcus ovis, a rare bacterium, following the use of a nose ring, highlighting its emerging role in cattle disease.

## Contribution

First confirmed case of pituitary abscess in a calf caused by Helcococcus ovis.

## Key findings

- Helcococcus ovis was isolated from a pituitary abscess in a calf with neurological symptoms.
- The bacterium was identified using MALDI-TOF mass spectrometry and gram stain.
- The case expands the known pathogenic range of H. ovis in cattle.

## Abstract

We report here the first confirmed case of a pituitary abscess in a calf caused by Helcococcus ovis, an emerging pyogenic bacterium in veterinary medicine. An 8-month-old calf showed progressive neurological signs following the use of a nose ring. Gross and histopathological examination revealed a large abscess in the pituitary gland accompanied by leptomeningitis, encephalitis, and plexus choroiditis. Helcococcus ovis was isolated from the pituitary abscess and identified by MALDI-TOF mass spectrometry with high confidence. Coccoid gram-positive bacteria were observed on gram stain of formalin-fixed tissues from leptomeningitis, plexus choroiditis and pituitary abscess lesions. Gross and histological features were indistinguishable from abscesses caused by other pyogenic organisms, highlighting the critical importance of bacteriological culture to diagnosis. This case expands the known pathogenic spectrum of H. ovis and suggests its inclusion in the differential diagnosis of suppurative central nervous system lesions in cattle.