Screening for Viral Nucleic Acids in the Cerebrospinal Fluid of Dogs With Central Nervous System Inflammation

Abstract

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.

New insights into the treatment of meningoencephalomyelitis of unknown origin since 2009: A review of 671 cases

“…The etiology of MUO is by definition unknown but, in addition to individual genetic predisposition, many autoimmune diseases are strongly suspected of having a trigger, which may be infectious, environmental or neoplastic (26). In contrast to recent developments in MS (27, 28) and despite extensive searches for infectious triggers, none have so far been identified for MUO in dogs (29)(30)(31)(32)(33)(34)(35)(36) and neither have broad environmental risks been identified in association with canine immune-mediated disease more generally (37), and so the etiology is assumed to be an idiopathic self-directed immune response. Nevertheless, the complicated immune-mimicry that underpins the relationship between Epstein-Barr virus and MS in humans implies that a similar relationship between an as yet unidentified pathogen and MUO cannot be ruled out.…”