Encephalitis in a rabbit caused by human herpesvirus-1

Case Description—An 8-month-old sexually intact male rabbit was examined because of a 2-day history of anorexia, epiphora of the left eye, bruxism, hypersalivation, and ataxia.

Clinical Findings—Physical examination of the rabbit revealed bilateral conjunctivitis, hypersalivation, and severe signs of CNS dysfunction such as incoordination, intermittent myoclonic seizures, and opisthotonus. Results of hematologic and serum biochemical analyses revealed only lymphopenia, a relative monocytosis, and an increase in serum activity of creatine phosphokinase and serum concentration of total protein. Serum antibodies against Encephalitozoon cuniculi and Toxoplasma gondii were not detected.

Treatment and Outcome—Despite IV administration of crystalloid fluids and treatment with antimicrobials, vitamin B complex, nutritional support, and prednisolone, the condition of the rabbit deteriorated; it was euthanized 7 days after admission. Histologic evaluation of brain tissue revealed lesions characteristic of severe, diffuse, nonsuppurative meningoencephalitis and a few large, eosinophilic, intranuclear inclusion bodies in neurons and glial cells. The DNA of human herpesvirus-1 was detected in the nuclei of glial cells, lymphocytes, and neurons by means of in situ hybridization. The rabbit's owner, who reported having had a severe labial and facial herpesvirus infection 5 days before the onset of clinical signs in the rabbit, was suspected to be the origin of infection for the rabbit.

Clinical Relevance—Human herpesvirus-1 may be transmissible from humans to rabbits, and infection with this virus should be considered as a differential diagnosis in rabbits with CNS signs of disease.