Mycoplasma bovis involved in pituitary abscess syndrome in a beef heifer concomitantly infected with haemoparasites

This case report describes pituitary abscess syndrome (PAS) in a 20‐month‐old Blonde d'Aquitaine heifer with cranial nerve deficits (V, VII, VIII, IX, X and XII) associated with facial hemiparesis, head tilt, ataxia and dysphagia, pneumonia and otitis interna. Despite extensive clinical, laboratory and imaging investigations, including a positive external ear canal swab for Mycoplasma bovis , a definitive diagnosis was not established. Euthanasia was elected due to poor clinical progression. Postmortem examination revealed a parahypophyseal abscess in direct continuity with the right tympanic bulla, severe chronic M. bovis ‐associated pneumonia and otitis interna. M. bovis was isolated from the lungs and abscess capsule. Trueperella pyogenes was also isolated from the abscess. This case highlights the diagnostic challenges associated with PAS, particularly in the presence of complex comorbid clinical conditions. It also suggests that M. bovis , beyond its well‐recognised role in respiratory and otic disease, may potentially contribute to PAS.