Ringworm is highly contagious


It seems each year about this time that ringworm becomes a concern, especially with those youth who exhibit their beef cattle projects.
Unfortunately there isn’t any FDA-approved drug to treat ringworm in cattle. This includes the materials that may be purchased from the “fitters” since none of it likely has an FDA approval despite what the label might say.
What is ringworm? Ringworm is a fungal disease like athlete’s foot. The fungal spores can persist in buildings from one year to the next, and it is common to see recurring outbreaks in young cattle, especially in the winter.
Sunlight is very helpful, and the disease seems to be very uncommon during the summer, only to flare up in during the winter when animals go into barns and perhaps when feed quality may be lower.
Usually an infection lasts about six weeks and the animals recover on their own. Most people don’t bother treating these outbreaks for that reason.
Similar disease. A similar disease, called club lamb fungus, has become quite common in show lambs because of the nature of the way they are managed – lots of washing, slick shearing, and blankets (think of athlete’s foot again).
However, ringworm in commercial sheep or purebred flocks that don’t exhibit is very rare. Most commonly, tincture of iodine is used to treat ringworm in cattle. Usually the 2 percent strength is used as it is less irritating to the skin.
There should be no “drug residue” problem with this chemical but it does stain the skin for a while and will stain white hair. The areas should be treated about once daily and a cotton ball soaked in the iodine works well to get the solution down to the skin. Usually a week or ten days is long enough, but it will take longer than that for the hair to come back in.
“Tamed” iodine preparations, such as Betadine, may be useful but tend not to wet the skin as well. On the other hand, they do not have quite the same tendency to stain skin and hair as the tincture of iodine.
Two issues. Two issues are important regarding ringworm. One is that all ringworm diseases of animals can be contagious to humans. Transmission isn’t really common, but it happens and has been an especially serious issue with club lamb fungus.
I recommend using rubber gloves when treating and handling these animals, at least until the lesions appear to be well along in healing. It is also true that even though the lesions may be healed, infectious fungal spores may still be on the animal’s hair, in the environment, and on equipment such as halters and leads, brushes and combs.
Therefore , it is also important to change clothes after handling infected animals and to frequently wash your hands and arms with soap and water.
Secondly, ringworm is contagious to other animals by direct contact or indirectly through a contaminated environment.
For this reason, it usually disqualifies an animal from exhibitions until the lesions have healed. It is true that sometimes this rule is not enforced, and is one reason why it is so common amongst animals in show circuits.
Treatment. There are many things that have been used to treat ringworm. Some of these include fruit tree sprays containing captan and products used for dogs and cats and humans.
These things can and do cause drug residue problems, and captan is now considered a low grade carcinogen. It can be absorbed through the skin.
Before using any of these kinds of things on a food animal, you should consult with your herd veterinarian. Even when these things are prescribed by a veterinarian, problems have arisen so caution should be exercised.
Keep things clean. Cleaning the barn thoroughly and paying special attention to feeders, walls, and rafters may be helpful in preventing an outbreak in newly purchased animals.
Some disinfectants, like Virkon S, and the phenolic disinfectants, like One Stroke Environ, do have activity against fungi.
If people only have steers for projects and the barn is empty for part of the year, this cleaning process can be useful. It would also be a good idea to clean and disinfect halters, leads, brushes and combs and other tack to prevent spread between animals.
Borrowing equipment from someone else can expose uninfected animals even if there is no current evidence of ringworm on the premises from which the equipment was borrowed.
(The author is a veterinarian for cattle and sheep at The Ohio State University Extension.)


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