Cow warts are typically found in people two years of age and younger.
Bovine papillomavirus (BPV) has six different strains that can cause warts in cows. The strains are characterized into six groups, BPV 1 to BPV 6. Warts in cows are caused by one strain of virus, therefore they are infectious. This virus can only be transmitted to other cows; people cannot be infected.
Warts can occur anywhere on the cow’s body. The location of the warts can help determine which type of wart the cow has contracted. BPV 1, BPV 5, and BPV 6 strains can cause warts on the reproductive organs or teats of cows, and BPV 2 and BPV 3 warts are found on the head and neck. The BPV 4 strain can cause warts to grow in the gastrointestinal tract.
Open wounds can allow papillomavirus to enter the cow’s body if it comes into contact with another infected cow or contaminated farm equipment. Certain insects also carry the virus and can infect the cow if she is bitten. The incubation period can last from a month to a year. Warts on cows are mostly found in people two years old and younger. Older cows develop a natural immunity to the virus.
The appearance of warts varies from strain to strain. Some warts are flat. Others resemble a bunch of cauliflower protruding from the skin, and still others are long, white lesions. If one cow has warts, the whole herd is more likely to have them. All cows are susceptible to the virus.
For the most part, warts on cows rarely cause any real physical problems. In rare cases, the warts can spread to the reproductive organs of the cow and cause pain, preventing reproduction in breeding stock. Dairy cows can develop warts on their teats. Milking can be painful, which can affect milk production. Unless warts affect productivity, they are usually not treated.
Dealers of thoroughbred or show cattle may suffer more when warts infect cattle. The presence of the warts makes it nearly impossible for traffickers to obtain disease-free health documents for the herd, making future sales difficult until the warts are gone. Many ranchers treat warts on cows by surgically removing them.
Commercial vaccination is an option, but if the herd has already had an outbreak of any type of wart, the chance that the vaccination will work is significantly reduced. If warts are not a problem in the herd, vaccination can help prevent their occurrence. The vaccines are usually given as two injections three to five weeks apart.