Eastern Equine Encephalitis in Dogs

Abstract

Eastern equine encephalitis virus (EEEV) is an Alphavirus that is endemic in the Southeastern United States. From 1993 to January 2005, the Veterinary Diagnostic and Investigational Laboratory in Tifton, Georgia, performed postmortem examinations on over 101 domestic canines exhibiting clinical neurological disturbances. In 12 of these dogs, brains were histologically suggestive of infection with EEEV. All dogs were less than 6 months of age, with no breed predilection. Clinical signs included pyrexia, depression, nystagmus, and lateral recumbency. Microscopically, brains from all 12 puppies contained infiltrates of lymphocytes, plasma cells, and histiocytes, with occasional neutrophils and random foci of astrocytosis and gliosis. There were mild to moderate perivascular infiltrates of neutrophils along with scattered lymphocytes, plasma cells, and macrophages in the meninges. Viruses isolated from brain homogenates of all 12 puppies were confirmed by indirect fluorescent antibody testing to be EEEV. Additionally, RNA extracted from the brains and viral cultures of 2 dogs were determined by a specific reverse-transcriptase polymerase chain reaction (RT-PCR) to contain EEEV. The single available serum sample exhibited a 1:8 serum neutralization titer to EEEV.