Central nervous system (CNS)
inflammation is a common cause of neurological dysfunction in dogs. Most dogs with CNS
inflammation are diagnosed with presumptive
autoimmune disease. A smaller number are diagnosed with an infectious etiology. Additionally, at necropsy, a subset of dogs with CNS
inflammation do not fit previously described patterns of
autoimmune disease and an infectious cause is not readily identifiable. Because
viral infection is a common cause of
meningoencephalitis in people, we hypothesize that a subset of dogs presented with CNS
inflammation have an occult
viral infection either as a direct cause of CNS
inflammation or a trigger for autoimmunity. The goal of this research was to screen cerebrospinal fluid from a large number dogs with CNS
inflammation for occult
viral infection. One hundred seventy-two dogs with neurological dysfunction and cerebrospinal fluid (CSF)
pleocytosis were identified. Of these, 42 had
meningoencephalitis of unknown origin, six had
steroid-responsive
meningitis-
arteritis, one had eosinophilic
meningoencephalitis, five had documented
infection, 21 had and undetermined diagnosis, and 97 had a diagnosis not consistent with primary inflammatory disease of the CNS (e.g.,
neoplasia). CSF samples were subsequently screened with broadly reactive PCR for eight viral groups: adenovirus, bunyavirus, coronavirus, enterovirus, flavivirus, herpesvirus, paramyxovirus, and parechovirus. No viral
nucleic acids were detected from 168 cases screened for eight viral groups, which does not support occult
viral infection as a cause of CNS
inflammation in dogs. La Crosse virus (LACV)
nucleic acids were detected from four cases in Georgia.
Subclinical infection was supported in two of these cases but LACV could not be ruled-out as a cause of
infection in the other two cases, suggesting further research is warranted to determine if LACV is an occult cause of CNS
inflammation in dogs.