Listeria monocytogenes encephalitis in a donkey foal

This is the first known case report of encephalitic listeriosis in a donkey (Equus asinus). A 5-day-old female donkey foal presented for fever, progressive weakness and loss of suckle reflex. Upon arrival, its vital parameters were normal, but the foal was collapsed. It had horizontal nystagmus, front limb paddling, minimal response to stimuli, prolapse of the left third eyelid and curling the neck to the left when in sternal recumbency. Samples collected for diagnostic evaluation included blood and cerebral spinal fluid. The cerebrospinal fluid (CSF) showed a pleocytosis consisting mainly of nondegenerative neutrophils and a normal protein concentration. Bacteria were not seen on Gram stain. After 24 h of treatment with intravenous fluids, anti-inflammatories, antibiotics, nasogastric feedings of the dam's milk and supplemental nasal oxygen, little improvement was observed and the owners elected to euthanise the foal. Post-mortem examination revealed multifocal, irregularly distributed hepatic necrosis and multifocal lymphohistiocytic encephalitis. Listeria monocytogenes was isolated from a section of brainstem.