Pituitary Abscess Syndrome in Ruminants: Nine Cases

Pituitary abscess syndrome (PAS) is a rare neurological disorder, typically associated with progressive dysfunction of the cerebrum and brainstem. Reporting PAS in ruminants is essential to broaden the global veterinary understanding of this condition. The present study describes the epidemiological, clinical, laboratory, microbiological, and pathological findings of nine ruminant cases diagnosed with PAS. Neurological signs were the most prominent clinical manifestations and included altered mentation, tongue hypotonia, nystagmus, blindness, ear ptosis, circling, facial hypoalgesia, head pressing, and proprioceptive deficits. Hematological alterations in some animals comprised leukocytosis by neutrophilia, a degenerative left shift, and hyperfibrinogenemia. Serum biochemical abnormalities were inconsistent and varied among cases. Cerebrospinal fluid (CSF) analysis revealed marked variability, ranging from normal parameters to mild or marked pleocytosis, often accompanied by hyperproteinorrachia. Microbiological cultures from CSF samples or abscess material yielded Trueperella pyogenes, Streptococcus spp., and Corynebacterium spp. Gross pathological findings primarily included pituitary hyperemia, abscess formation, or diffuse suppurative inflammation characterized by a creamy yellow to greenish exudate. Histopathological examination revealed severe multifocal suppurative inflammation composed predominantly of neutrophils, occasional histiocytes, abundant bacteria, areas of necrosis, and encapsulated abscesses. This retrospective study provides novel insights into the clinical, laboratory, and pathological characteristics of PAS in ruminants under field conditions, thereby contributing to improved recognition and diagnostic understanding of this uncommon disease.