an abstract from PubMed
Epidemiology of reindeer parasites. Halvorsen O. Parasitol Today. 1986 Dec;2(12):334-9.
Every Christmas we sing about Rudolph the red-nosed Reindeer, but do we give much thought to why his nose is red? The general consensus is that Rudolf has caught a cold, but as far as I know no proper diagnosis has been made of his abnormal condition. I think that, rather than having a cold, Rudolf is suffering from a parasitic infection of his respiratory system. To some this may seem a bit far-fetched as one would not expect an animal living with Santa Claus at the North Pole to be plagued by parasites, but I shall show otherwise.(as posted on The World's Fair)