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Animal Warts

    Although the bumps on the skins of toads are called “warts,” they are, in fact, not warts at all (e.g., they are not caused by a papillomavirus and not related to any infectious process). The bumps that we call warts are part of a toad’s protective camouflage and help it blend in with its dry, rocky environment. The toad’s “warts” may also contain glands that secrete toxins and discourage predators from eating the toad.  Humans can not get warts from handling toads, because toads do not have viral warts. There are, however, many species of animal that can develop actual warts caused by strains of papillomavirus. In fact, warts can be found in all domestic animal species, including birds and fish. Cattle, horses, and dogs are the domestic animals most commonly affected by warts. Animal warts are mainly a cosmetic concern, but because they are caused by a virus, animals that have warts are not allowed to enter shows or competitions.

    The papillomaviruses that cause warts on animals are breed-specific--bovine papillomavirus causes warts in cows but can not cause warts in humans or dogs (or any other species). It is common for young animals to develop clusters of warts and older animals to develop a single wart. Insects (i.e., ticks, mosquitoes) likely transmit the papillomavirus between animals. Young animals are often affected by warts on the face and neck because the skin is thinner and the hair has not grown as dense as on older animals.

    In cattle, warts are likely to develop on the head, neck, and shoulders. The papillomavirus often infects the cow through a break in the skin. The warts begin to appear about 8 weeks after the cow is infected with the virus and last for about 1 year. Calves are most susceptible to the papillomavirus; it is rare to find warts on a cow that is older than 2 years.

    Horses develop warts on the nose, lips, eyelids, legs, genitals, and udder and inside the ears. Again, the virus often infects the animal through broken skin. Warts resolve in a matter of months on young horses and may last for over a year on older horses.

    Young dogs can develop mucous membrane papillomatosis, or warts in and around the mouth and throat. The warts are usually harmless but can interfere with the animal’s ability to chew and swallow. Older dogs generally develop solitary warts in the mucous membranes.

    The most common treatment for animal warts, whatever the species, is to let the wart run its course. It is always a good idea to isolate infected animals, so the virus does not spread. Be careful to sterilize all tack or equipment that has touched an animal that suffers from warts before using it on another, non-infected animal. Surgical removal of animal warts is an option.


Indiana State Board of Animal Health [Internet].  Preventing Animal Warts. Indiana State Board of Animal Health Tech Bulletin RC4-11.98 [cited 2010 Jun 15]. Available from: http://www.in.gov/boah/files/RC411warts.pdf

Purdue School of Veterinary Medicine [Internet]. Morter RL, Horstman L. Cattle warts: bovine papillomatosis [cited 2010 Jun 15]. Available from: http://www.ces.purdue.edu/extmedia/VY/VY-58.html

TheHorse.com [Internet]. Blood Horse Publications; c2010. Miller W Jr. Warts [cited 2010 Jun 15]. Available from: http://www.thehorse.com/ViewArticle.aspx?ID=661

The Ohio State University Extension [Internet]. Knebusch K. Smart Stuff With Twig Walkingstick: toad warts [cited 2010 Jun 16]. Available from: http://www.ag.ohio-state.edu/~news/story.php?id=3142

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