Outbreaks and sporadic cases of the pituitary abscess syndrome are described in calves in the state of Rio Grande do Sul, southern Brazil. The disease occurred in eight beef cattle farms in the municipalities of Cachoeira do Sul, Lavras do Sul, Bagé, Osório and Vila Nova do Sul, from 1998 to 2002. Thirty-five (1.4%) out of 2,438 calves with 3-12 months of age were affected and 24 (0.98%) died. A nasal plastic device to prevent suckling had been used in all the affected calves. Clinical signs consisted of nasal discharge, depression, hyperthermia, ataxia, circling, head tilt and hypermetria, exophtalmos, dysphagia, partial mandibular paralysis, prolapse of the tongue, difficulty in chewing, drooling and in some cases blindness accompanied or not by aqueous flare, prolapse of the ocular globe and corneal opacity. In the terminal stages of the disease, there was lateral recumbency, opisthotonus and coma. The main necropsy findings included single large hypophyseal or para-hypophyseal abscesses. Those space-occupying lesions dorsally compressed the brain stem and the cranial nerves adjacent to the hypophysis. In some cases, there was also osteomyelitis of the basisphenoid bone, single or multiple brain abscesses and leptomeningitis affecting the ventral surface of the brain stem and cervical spinal cord. In a few cases, necrotizing or abscedative rhinitis associated with nose device injury was observed. Histologically, those abscesses consisted mainly of neutrophils admixed with cellular debris surrounded by numerous mononuclear cells and a fibrous capsule. Fibrino-suppurative meningitis affecting the leptomeninges of the cerebellum, brain stem and cervical spinal cord was also observed. In some cases, purulent inflammation extended into the hypophyseal parenchyma. Arcanobacterium (Actinomyces) pyogenes was isolated from the abscesses. The diagnosis of pituitary abscess syndrome was based on epidemiological data, clinical signs, necropsy findings, histological alterations and bacterial cultures.
Abscess; pituitary; rete mirabile; nose device; diseases of cattle; pathology; central nervous system
