Almost all warm-blooded animals are vulnerable to anthrax.

Most anthrax victims, however, are herbivores, especially grazing animals such as cattle and sheep. Other domesticated creatures— such as horses, mules, goats, camels, oxen, and llamas—are also very susceptible to the disease. So are many wild animals. For example, anthrax is common in antelope, deer, elk, reindeer, guinea pigs, mice, and rabbits. Anthrax outbreaks caused by contaminated forage have even been reported among elephants and hippopotamuses.

Cats, dogs, pigs, and birds rarely catch anthrax, and cold-blooded creatures never do. Scientists believe that basic differences in anatomy and physiology make some animals more susceptible to certain microbes than others. Thus, many carnivores—including dogs and cats—appear to have some natural resistance to anthrax, as do some omnivores such as pigs.

For other creatures, high or low body temperatures contribute to their immunity to...