Skin Problems in Young Cattle: Warts and Ringworm
March 19, 2013
Two unsightly skin diseases often appear during winter. Dr. Matt Miesner, Kansas State University says young animals are highly susceptible to warts and ringworm until their immune systems have encountered the causative organisms and built immunity. "Older cattle have been exposed before and rarely express these problems. If I see warts or ringworm in an older animal I suspect they have an immune deficiency or the immune system is hindered by stress or some other problem," he said.
Warts are caused by a virus, and may appear in several animals at once. "Young bulls may have penile warts, a specific type of papilloma virus, but there are at least 12 different papilloma viruses that cause warts. Other types affect the skin, gastrointestinal tract or teats," Miesner said.
Warts on the skin often appear where skin has been broken, allowing the virus to enter. They may develop in ears after tagging. If a person is tagging several animals it pays to disinfect the tagging tool between animals. "All it takes is a scratch or wound and the virus sets up shop. Fortunately, most warts go away after a few months," he said.
Warts are most common in weanlings and yearlings. The growths appear quickly, becoming a rough-looking or smooth-shaped mass. They may be small and rounded or very large. A large mass in an ear may be so heavy the ear droops down.
The virus can be spread from animal to animal or by contact with something the infected animal has touched. If cattle are itching on a fence the virus may be passed around. "One goes by and scratches on the post and the next one picks it up. The entire group may be exposed but not all of them will develop warts," Miesner added.
"If a new animal comes into a herd (or cattle have contact with neighbor's cattle) and brings a different type of virus that your animals have no immunity to, some of them pick it up. Eventually it spreads through the herd and they all develop immunity," he said.
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Warts often spread rapidly from the area in which they started. Then they dry up and fall off – once the body has time to develop antibodies against the virus. A healthy animal in good condition will build an immune defense and generally never get warts again.
If the warts are a problem around the mouth or nostrils, interfering with breathing or eating, or on the teats, their disappearance can be hastened by carefully pulling, twisting or snipping off one of the warts, crushing a small one, or removing part of a large mass. Disrupting the wart encourages the animal's immune system to create antibodies; the virus in the disrupted tissue comes into contact with the bloodstream if the area bleeds a little.
"A multivalent commercial vaccine for warts is made by Colorado Serum Company. The company continually acquires samples of different types of warts and makes antigens in their vaccine. This is effective against most warts. Vaccination could stimulate immunity in a herd and reduce incidence of warts. But we don't see complete elimination of the problem, due to variations in individual immunity and response to the vaccination," Miesner explained.
"Another option, if that doesn't work (since there are so many different types of warts) is to have an autogenous vaccine created from pieces of warty tissue from your own animals. You generally need to collect at least 200 grams of the wart, and the company may require that you order a certain number of doses of vaccine. It might not be worth it, for just a few cattle, but cost effective if you have a large-scale problem," he said.
"The vaccine won't make warts shrivel up much faster if they are already present, but can reduce the number of warts that appear. Bull studs often vaccinate to reduce penile warts," said Miesner.
"We always check for these in a breeding soundness exam. This is one reason we make the bull extend his penis so we can look at it. The wart itself is generally not a problem, and young animals generally resolve these on their own. But if the bull tried to breed a cow and bleeding occurred due to disruption of a wart, the semen would become ineffective, rendering him infertile. If the warts don't resolve quickly enough we may remove them. The local inflammation from removing warts creates more immune response from the bull," Miesner said.
Warts on teats are found primarily on heifers, but can also affect older cows. "In dairy cows these can be a serious problem, interfering with milking. We can vaccinate them to stimulate immunity to get rid of them. Some of the things that look like warts may be scar tissue from earlier warts or some other teat injury," he continued.
It's not a good idea to use iodine or any other caustic disinfectant on warts. These treatments are effective for ringworm (caused by a fungus) but not for the wart virus, and may be harmful. The best treatment is time, letting warts disappear on their own.
Warts are species specific, so you won't get warts from your cattle. "The only exception of interspecies transmission is that a couple of the bovine viruses are implicated in equine sarcoid tumors," Miesner said. If cattle and horses are pastured together, this could be an issue if a horse develops sarcoid from a break in the skin.
This fungal skin disease often appears in calves and yearlings during winter, but generally disappears without treatment by spring. There are several species of Trichophyton and Microsporum fungi that cause ringworm.
"Ringworm can spread from species to species, including humans. There are common types for cattle and other types in other species, but there are so many different types that it is hard to have immunity against all of them. Livestock are screened at Fairs and shows when they check in, to make sure they don't have ringworm," explained Miesner.
The fungal spores may be spread by contact with an animal that has ringworm or by spores in the environment – something an infected animal has rubbed on. Spores can be spread by equipment used on an infected animal and then a susceptible one – such as a rope or halter, grooming tool, or equipment used on more than one animal. The fungus becomes established on the skin of the susceptible animal and infiltrates hair follicles. Lesions develop about three weeks later. "One way to keep ringworm from spreading is to disinfect equipment used on more than one animal," Miesner said.
Spores may survive in the environment for years. Young cattle may develop ringworm in the fall and winter even if there weren't animals in the herd with ringworm during summer; the spores are waiting to infect susceptible animals when conditions are right. The fungus does best in dark, moist conditions.
In the early stages, affected areas are small, with raised skin and rough hair. After several weeks the hair falls out, leaving thickened patches of scaly gray lesions – often on the face, neck and around the eyes. Adult cattle have generally encountered the fungus and have built some resistance and don't get ringworm, but if spores are present on their bodies they may pass the disease to young, susceptible animals. The disease generally runs a course within a few weeks or months and disappears. Sunlight, dry conditions and adequate vitamin A in the diet may help animals get rid of the lesions quicker.
"Treating ringworm can be frustrating. The lesion will eventually resolve anyway," said Miesner. There are a number of anti-fungal drugs, but some of topical treatments such as iodine or chlorine bleach only work if you first wash and remove the scabby lesions with soap, water and a stiff brush before applying the medication.
"Anti-fungal medications such as for athlete's foot in humans are expensive to use on large animals. Sodium iodide given IV may also work but can have side effects like scaling/flaking skin. The oral drugs for humans would be cost prohibitive in cattle. We also don't have established withdrawal times for these medications, so we need to be cautious about what we use on cattle," Miesner advised.