First report of Filaria martis Gmelin, 1790 in the European mink, Mustela lutreola (Linnaeus, 1761)

The riparian European mink (Mustela lutreola),
currently surviving in only three unconnected sites in
Europe, is now listed as a critically endangered species according
to the IUCN. Habitat loss and degradation, anthropic
mortality, interaction with the feral American mink (Neovison
vison), and infectious diseases are among the principal causes
of its decline. Surveys of helminth parasites of this host that
also include focus on subcutaneous potentially pathogenic
helminths such as those belonging to the genus Filaria are
very scarce. We report here the presence of specimens of
Filaria martis in the subcutaneous connective tissues of three
M. lutreola individuals from Spain. This is the first finding of
a subcutaneous nematode in a representative of the genus
Mustela. The report also enlarges the known range of the
definitive hosts of this nematode. These worms were mainly
located in the dorsal region of mink and more rarely in the
knees, elbows, and hips. Skin sloughing was only observed in
one M. lutreola with both septicaemia and an associated high
burden of F. martis. Therefore, more attention should be paid
to potentially pathogenic helminths when designing conservation
programs dedicated to M. lutreola.