Absence of hantavirus in water voles and Eurasian beavers in Britain.

Hantaviruses are RNA viruses (order Bunyavirales, family Hantaviridae) found in rodent, bat and insectivore reservoir-hosts and have been reported as an emerging significant zoonotic risk in Europe. As part of two native semiaquatic rodent restoration projects, tissue and urine samples were tested for hantavirus from water voles (Arvicola amphibius) (n=26, in 2015) and Eurasian beavers (Castor fiber) (n=20, covering 2010-2015) using a pan-hantavirus nested real-time PCR test. Kidney and lung samples were also analysed by light microscopy after haematoxylin and eosin staining of formalin-fixed paraffin wax sections. Individuals selected included those forming the source of release animals and from those already free-living in Britain in areas targeted for release, to identify existing reservoirs. For water voles all tested individuals were from Britain (n=26); for beavers some were from Britain (Scotland) (n=9) and some were samples from wild Norwegian (Telemark region) (n=6) and German (Bavaria region) animals (n=5) that formed the source of accepted wild populations currently present in Scotland. All samples tested from both species were negative for hantavirus RNA and showed no significant histopathological changes suggesting that reservoir infection with hantavirus in water voles in Britain and Eurasian beavers present in Britain, Norway and Bavaria, Germany, is unlikely.

Haematology and Serum Biochemistry Parameters and Variations in the Eurasian Beaver (Castor fiber).

Haematology parameters (N = 24) and serum biochemistry parameters (N = 35) were determined for wild Eurasian beavers (Castor fiber), between 6 months - 12 years old. Of the population tested in this study, N = 18 Eurasian beavers were from Norway and N = 17 originating from Bavaria but now living extensively in a reserve in England. All blood samples were collected from beavers via the ventral tail vein. All beavers were chemically restrained using inhalant isoflurane in 100% oxygen prior to blood sampling. Results were determined for haematological and serum biochemical parameters for the species and were compared between the two different populations with differences in means estimated and significant differences being noted. Standard blood parameters for the Eurasian beaver were determined and their ranges characterised using percentiles. Whilst the majority of blood parameters between the two populations showed no significant variation, haemoglobin, packed cell volume, mean cell haemoglobin and white blood cell counts showed significantly greater values (p<0.01) in the Bavarian origin population than the Norwegian; neutrophil counts, alpha 2 globulins, cholesterol, sodium: potassium ratios and phosphorus levels showed significantly (p<0.05) greater values in Bavarian versus Norwegian; and potassium, bile acids, gamma globulins, urea, creatinine and total calcium values levels showed significantly (p<0.05) greater values in Norwegian versus Bavarian relict populations. No significant differences were noted between male and female beavers or between sexually immature (<3 years old) and sexually mature (≥3 years old) beavers in the animals sampled. With Eurasian beaver reintroduction encouraged by legislation throughout Europe, knowledge of baseline blood values for the species and any variations therein is essential when assessing their health and welfare and the success or failure of any reintroduction program. This is the first study to produce base-line blood values and their variations for the Eurasian beaver.