Vet Advice

After countless hours of feeding, cleaning, grooming and training, a 4-H calf is ready for the show circuit. Not only is this calf a learning project, it is also a source of pride for the 4-H member, and definitely needs to be displayed at the exhibitions. You can imagine, or may have experienced, the anguish that ringworm brings to the 4-H member whose calf is affected.

Because ringworm is a transmissible infectious disease, animals with active lesions are usually barred from exhibitions or shows. To make matters worse, 4-H calves are often penned together on a farm, so that ringworm spreads through the group.

Transmission

Ringworm in cattle is usually caused by a fungus called Trichophyton verrucosum, which infects the hairs and outer layers of the skin. Direct contact with infected animals is the most common method of transmission, however, even contact with grooming instruments, halters, fences, or feed bunks can cause infection. One to six weeks after transmission of the fungus, hairless, crusting, grey-white scabs appear. These circular lesions (hence the name "ringworm") are most frequently on the head and neck, especially around the eyes, but may in severe cases be found over the entire body.

Why does the 4-H calf in the pen, not the cattle grazing in the field, get the disease? Age is likely the most important factor. Young cattle haven't had exposure to the disease, and so haven't developed the immunity yet. Another important factor is crowding in a pen, allowing for increased contact. Show calves are especially at risk because of the added possibility of frequent contact with infected grooming equipment. Housing indoors in a dark, damp area, and inadequate minerals or poor nutrition also predispose to ringworm.

Treatment

Since spontaneous recovery usually occurs after one to six months, and the cost of treatment (drugs and labour) are significant if large pens are involved, I generally do not recommend treatment for calves that are not 4-H calves and will not be shown. That is, of course, unless they are severely affected animals. There are 101 ways to treat ringworm that will appear to work because the disease spontaneously regresses. So what do you use? Toothpaste, used crankcase oil, creosol?

For large groups, a topical spray-on fungicide, applied over the entire body for three days, and reapplied weekly thereafter until the infection has resolved, is the most practical, and effective in my experience. Some topical fungicides are enilconazole, five per cent lime sulfer, sodium tolnaftate, thiabendazole, plant fungicides such as CaptanR, and chlorhexidine. Iodides (iodide shampoos, tinctures) and fluorides (toothpaste) are also effective. For individual show animals the quickest and most effective treatment is oral medication with griseofulvin; however, this should be directed by your veterinarian.

The important thing to remember about topical medication is that the scabs/crusts need to be scraped off with a stiff brush in order for the medication to be effective. Also, be careful applying the medication around the eyes!

Finally, just putting the calves out into sunlight will often help resolve the lesions.

Prevention

Commercial vaccines have been available in the past; however, the results were variable. Currently the best method of control is to be very diligent about cleaning. The spores can remain alive for years and because they do, wood fences, feed bunks, halters and grooming equipment can remain infective for years for years. Cleaning and disinfecting barns and grooming equipment with a solution of one gallon of household bleach diluted with three gallons of water does a good job. Reducing the density of animals and direct contact, in addition to increased exposure to sunlight, help prevent spread between animals. Finally, be sure to include adequate minerals in the diet.

I've learned never to say "never" but with these control methods you can markedly reduce the chance of your 4-H calf getting ringworm.