The naked fox: hypotrichosis in arctic foxes (<Emphasis Type="Italic">Alopex lagopus</Emphasis>)

We describe the manifestations and occurrence of hypotrichosis in arctic foxes and compare it to the Samson character in red foxes. During 1979–2005, we collected carcasses of both normal and hypotrichotic arctic foxes from foxhunters in Iceland for macroscopic and microscopic examination and study of demography. We obtained live pups for breeding and transmission experiments in captivity during 1985–1992. Placental scar counts showed that hypotrichotic vixens were more fertile than normal vixens and generally all their pups were hypotrichotic. Fertility in hypotrichotic vixens was positively correlated with winter air temperature but not in normal vixens. Hypotrichotic males were less likely to breed than normal males and probably had a higher mortality rate than either hypotrichotic females or normal foxes. Hypotrichosis can be transmitted between adult foxes. Microscopic examination revealed prominent chronic inflammation of the dermis in hypotrichotic specimens, degenerative changes, vacuolisation and necrosis of hair follicles. Hypotrichosis persists in coastal areas with mild winters and may become more common with global warming.