A dog was euthanatized because of progressive neurological signs. Hist
ologically, a nonsuppurative meningoencephalitis was found. By immunoh
istochemistry, in situ hybridization, and nested PCR procedures, Borna
disease virus (BDV) antigen and BDV-specific RNA were demonstrated in
brain tissues of the dog. The nucleotide sequence of the PCR product
showed 94 to 98% homology to published BDV sequences. This is the firs
t description of Borna disease in a dog.