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In many cases of inflammatory diseases of the central nervous system in dogs, no aetiological infectious agent can be found. These inflammatory conditions are thus named inflammations of unknown aetiology. Results of immunpathological studies imply that an antigen may trigger an autoimmune response (Hit-and-Run-Hypothesis).
Serum was analyzed for antibodies against vector-transmitted pathogens and blood and cerebrospinal fluid for DNA of such infectious agents in order to further define the role of CVBD-agents in the aetiology of meningitis and meningoencephalitis of unknown aetiology in dogs in Germany.
66 client-owned dogs were included in the prospective multicenter study between december 2009 and november 2011. They were classified in three groups:
a.) control-group with dogs with non-inflammatory CNS-disease (e.g. intervertebral disc
disease, n=21) (trauma group)
b.) dogs with meningoencephalitis of unknown aetiology (MUE) (n=22)
c.) dogs with steroid-responsive meningitis-arteritis (SRMA) (n=23)
PCR was performed in blood and cerebrospinal fluid to detect A. phagocytophilum, E. canis (for dogs that stayed in an endemic area or dogs with unknown past, n=28) and Bartonella spp. Serological assays targeted E. canis (IFAT), TBEV (ELISA) and Borrelia burgdorferi sensu lato antibodies (IFAT and C6-ELISA for patients with elevated antibody titers in IFAT). Group comparison was done with non parametric tests, using the statistical software SPSS 17.0 for windows, SPSS Inc., USA.
No DNA was found in cerebrospinal fluid. In 4 dogs of the SRMA-group, DNA of A. phagocytophilum was found in blood. Serological and PCR analysis for E. canis were negative in all dogs in blood and serum. No elevated antibody-titers against TBEV were measured in any dog. B. henselae DNA was detected in blood of 1 dog of the SRMA-group. 14 dogs had an elevated antibody titer (> 1:128) against B. burgdorferi sensu lato (IFAT). There were no significant differences between the 3 groups. In two dogs of the SRMA-group and in one dog of the MUE-group, an elevated C6-titer was detected via C6-ELISA (> 10
U/ml). DNA of Pasteurellaceae was detected with eubacterial PCR in CSF of 3 dogs of the trauma group, which may be due to a contamination of the samples.
No correlation could be determined between the presence of E. canis DNA or elevated antibody-titers against E. canis or TBEV and inflammatory CNS diseases. 17 % of dogs with SRMA had positive PCR results for A. phagocytophilum. A. phagocytophilum may play a role as trigger of a secondary immunopathy. It remains unclear whether the positive test results for Bartonella DNA and Borrelia burgdorferi sensu lato antibodies are clinically relevant.