The bovine papillomavirus (BPV) has six different strains that can cause warts on cows. The strains are characterized into six groups, BPV 1 through BPV 6. Warts on cows are caused by a virus strain, so they are infectious. This virus can be transmitted only to other cows — people cannot be infected.
Warts can occur on any part of 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 cow’s reproductive organs or teats, and BPV 2 and BPV 3 warts are located on the head and neck. The BPV 4 strain can cause warts to grow in gastrointestinal tract.
Open wounds can allow the papillomavirus to enter the cow’s body if it comes into contact with another infected cow or contaminated farming equipment. Certain insects also carry the virus and can infect the cow if it’s bitten. The incubation period can last from one month to one year. Warts on cows are mostly found on those that are two years old or younger. Older cows build a natural immunity to the virus.
The appearances of the warts vary from strain to strain. Some warts are flat. Others resemble a cauliflower cluster that protrudes from the skin, and others are long, white lesions. If one cow has warts, then the entire herd most likely will have them. All cows are susceptible to the virus.
For the most part, warts on cows rarely cause actual physical problems. In rare cases, warts can spread to the reproductive organs of the cow and cause pain, keeping breeding cattle from reproducing. Dairy cows can grow warts on their teats. Milking can become painful, which can affect milk production. Unless the warts affect productivity, the warts usually are left untreated.
Purebred or show cattle dealers can suffer the most when warts infect their cattle. The presence of the warts makes it almost impossible for the dealers to get disease-free health papers on the herd, making future sales difficult until the warts are gone. A lot of cattle dealers will treat warts on cows by surgically removing them.
Commercial vaccination is an option, but if the herd has ever had an outbreak of any type of wart, then the probability that the vaccination will work is significantly decreased. If warts have not been an issue within the herd, vaccinations can help prevent warts from happening. The vaccinations usually are given in two injections three to five weeks apart.