Bovine Papillomavirus (Cattle Warts)

Barry Whitworth, DVM - Area Food/Animal Quality and Health Specialist for Eastern Oklahoma

Herd of black and white cows in summer sunny field in countryside on pasture. Funny mammal animals wildlife outdoor at nature on green field. Livestock and cattle breeding. Agriculture at farm.

Bovine warts are the ire of cattle producers. These unsightly masses typically appear on the head, neck, and body of the animals. Although these masses are usually more of a cosmetic issue than a medical concern, they can cause problems for producers. Warts reduce the value of animals through loss in sales, reduced weight gain, and loss of milk production. The warts also create havoc with cattle exhibitors since cattle shows bar any animals with contagious conditions from entering the show ring.

Cattle warts are caused by the bovine papillomavirus (BPV) which is a member of the Papillomaviridae family. BPV is found throughout the world wherever cattle are present. Several different genotypes of BPV have been found. Most of the genotypes are species specific which means cattle warts are not contagious to other species like humans. A few exceptions have been found. For example, BPV can infect horses resulting in equine sarcoid tumors.

Transmission of the virus occurs when the virus enters the skin through some type of abrasion or wound. This can be accomplished through direct contact between animals. It can also be spread by contact with objects contaminated with the virus. Some research indicates the possibility of insect transmission.

While some cattle are infected with BPV and never display any clinical signs of the disease, those that do show clinical signs are usually found in cattle less than 2 years of age. BPV is associate with cutaneous papillomas or fibropapillomas. A papilloma is a lobulated benign tumor arising from the skin. A fibropapilloma is a papilloma containing a large amount of fibrous tissue. Typically, the warts have a cauliflower appearance or are round hairless raised areas on the skin. The skin tumors can be found all over the body. If warts are found in certain areas such as the prepuce, penis, vaginal area, or teats, problems with reproduction, milking, or bleeding may occur. Secondary bacterial infections can also be a problem in cattle with warts. Tumors associated with BPV involving the gastrointestinal tract have been found in cattle. The masses are found on the mouth, tongue, esophagus, and digestive tract. The tumors are normally benign unless the animal is immunocompromised. In other countries, BPV has been associated bladder cancer. These cattle typically consume large amounts of bracken fern, are immunocompromised, and are infected with BPV. Bracken fern is not typically eaten by cattle in the United States.

Following an immune response, most warts spontaneously regress in a few months. However, due to their unsightly nature, many cattle producers want to get rid of the warts as fast as possible. This has led to a variety of treatments. Practices such as feeding cattle the crushed pieces of the wart, pinching off the warts, and applying different types of topical treatments have been tried. Unfortunately, very few if any of the above-mentioned treatments have been scientifically studied, so recommendations are based on experience and opinions. Cattle producers should consult with their veterinarian for the best treatment options.

Prevention of warts requires producers to follow biosecurity protocols. Never introduce an animal with warts to the herd. If any animal in the herd develops warts, the animal should be isolated and returned to the herd only after the completely healed. Keep all areas of the ranch clean. Especially, sanitize areas where cattle have contact such as feed bunks, water troughs, and places where cattle might rub or scratch.

Commercial vaccines are available. Vaccine failure may occur if the strains of the virus in the vaccine do not match the strain causing the infection. To avoid this issue, cattle producers may want to have a vaccine developed by a laboratory with a specific strain. This can be accomplished with the help of a veterinarian.

Fortunately, if producers are patience, warts will spontaneously regress in time. If producers cannot wait, they should consult with their veterinarian for the best treatment options. For those producers that have problems with warts every year, a vaccine should be considered. If producers would like more information on bovine papillomavirus, they should consult with their veterinarian and/or Oklahoma State University Cooperative Extension County Agriculture Educator.

Read more in the July 2022 issue of Oklahoma Farm & Ranch magazine.

References

Bocaneti, Altamura, G., Corteggio, A., Velescu, E., Roperto, F., & Borzacchiello, G. (2016). Bovine Papillomavirus: New Insights into an Old Disease. Transboundary and Emerging Diseases, 63(1), 14–23.