Descriptive epizootiological study of European brown hare syndrome in Sweden.

A study on descriptive epizootiology of the viral necrotising hepatitis of hares, European brown hare syndrome (EBHS) was conducted in Sweden. Two thousand eight hundred eighteen hares were necropsied between 1980 and 1989. European brown hare syndrome was diagnosed histologically in 234 (14%) of 1644 European brown hares (Lepus europaeus) and 26 (3%) of 958 varying hares (Lepus timidus). Most cases occurred in October, November, and December. In 1980, the first cases were recorded on the island Gotland and in 1981 EBHS occurred on the mainland in the south of Sweden. In the following years it spread northward up to the Nordic limit (Limes norrlandicus), which marks the transition of climate, topography, fauna and flora, between central Sweden and Norrland. By 1989 EBHS was restricted to the southern terrain, overlapping the distribution of the population of European brown hares, and it occurred in 23.2% of the hares received for post-mortem examination at the National Veterinary Institute of Sweden.