First tick-borne encephalitis in a dog resident in Northern Germany

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Tick-borne encephalitis (TBE) is a mainly tick-transmitted viral disease in humans and mammals. It is caused by several subtypes of tick-borne encephalitis virus (TBEV), genus flavivirus, endemic in Asia, southeastern and central Europe. In Germany most cases of tentatively infected dogs with neurologic signs were mainly investigated serologically. Intralesional demonstration of the causative agent and molecular characterisation has been described in dogs exclusively in other countries. A three and a half-year-old male-neutered Saint Bernard dog, resident in northern Germany, developed subsequent to routine vaccination paresis and dyspnoea and was euthanised due to poor prognosis. Pathomorphologically, a severe multifocal lympho-histiocytic meningo-encephalomyelitis with neuronophagia and intralesional TBEV antigen was found. Using PCR and sequencing, genome fragments of the European subtype of the virus were detected. Immunophenotyping of the inflammatory infiltrate revealed predominantly T-lymphocytes and macrophages/microglial cells with an extensive expression of MHC-II. TBE was confirmed in a dog resident in northern Germany for the first time. In most canine cases of TBEV infection, virus is eliminated rapidly without a central nervous inflammatory reaction. Whether routine vaccination in this case interacted with virus clearance, remains undetermined. TBE has to be regarded as differential diagnosis also in northern Germany in dogs with neurological signs. As prevention the application of effective repellents is recommended.