Deep snow favours the large-footed cat. Large birds of prey kill fox pups that are in the open. Eagles even occasionally swoop at adults. The fox either takes up a defensive position, rigid and tense, with its tail straight up in the air, or it attempts to elude the eagle by dodging. Like all the other member of the dog family, foxes are susceptible to a wide range of parasites and diseases.
Most adults suffer to some degree from roundworms, tapeworms, and flukes.
Foxes that feed heavily on rabbits and deer carrion are more likely to be bothered by tapeworms than are those who eat mice. Parasites can be a big problem with the fox pups. A large percentage of pups that die each year are killed by parasites such as tapeworm. The pup becomes too weak to eat and dies. The fox is also a carrier of rabies, which kills a large number of red foxes each year.