Ringworm is a very common condition, especially in young stock, during the winter months. It is caused by several different fungi, which are fairly widespread in the environment. Generally ringworm is not a huge concern, save in two situations. Firstly, it is a zoonotic disease, meaning that humans can contract it. Secondly, it is a major concern when it infects show cattle, 4-H calves, or cattle being exported by purebred breeders. For these reasons alone, it is worth discussing.
Ringworm develops as crusty circular lesions with hair loss, starting primarily near the eyes and on the face. Most species of animals can contract ringworm, but it is more common in younger animals not previously exposed to the condition. In a more isolated herd where it has not been present for several years, you will notice it on mature stock as well. However, it is not as common to see ringworm in older animals as having contracted ringworm previously provides immunity. Also, mature cattle don’t have the stressors of rapid growth, weaning, or parasite burdens which weaken the immune system and healthiness of the skin, making it more likely the animal will contract ringworm. Healthy skin is a great barrier against the condition.
Vitamins A and D are necessary for healthy skin, so a good shot of these vitamins is a common add-on to treatment. Vitamin D is present in sunlight and this helps kill this organism as well. This is why clinical cases crop up in the winter and often disappear spontaneously in the summer.
You have a simple choice if you are worried there is too much ringworm developing in a commercial herd. If the ringworm is largely in small patches confined mainly to around the eyes or on the face and neck, it is of no concern to the animal. Weight gains will be normal and research has proven animals infected with ringworm do not have increased susceptibility to other diseases. However, if ringworm spreads over the rest of the body, these animals are suffering some distress and should definitely be treated.
Ringworm is a relatively slow infection to contract and to treat. In my opinion, producers tend to treat at a higher frequency than necessary. One or two treatments at weekly intervals are usually all that is necessary. If the crust is not redeveloping and the skin looks healthy with small hairs starting to grow back, you are on the road to recovery. It will take quite a while for the hair to completely fill in.
Show and 4-H animals should be back to normal three to four weeks after the last treatment. Treatment consists of taking a stiff bristled brush (don’t use this brush for anything else) and removing the crusty material. This should reveal a red, inflamed underside and exposing the area allows any treatment applied to contact the actual ringworm fungus. I use commercial products such as “Kopertox.” They stain the hair green which lasts for a while, so if shows or displays are just around the corner, then apply hibitane cream, Crest toothpaste or thiabendazole deworming powder (if available from your veterinarian). I generally repeat the treatment one week later. The beauty of these other products is they have a more natural white to creamy colour and can be removed if necessary.
As mentioned, you can contract ringworm from cattle or other species that have it, so be careful. Practise strict biosecurity measures: Wear gloves, wash well afterwards, and try to avoid rubbing against ringworm lesions. Put brushes used when treating the condition in a plastic bag and label it so others don’t mistakenly use them for another procedure. Ringworm spreads by direct contact so regular brushes, halters and saddles, or saddle blankets in horses can easily spread it from one animal to another. By the time you see ringworm, others in the same pen have probably already been exposed and may or may not develop it. Therefore isolation, in my opinion, is generally not necessary.
If it’s been a bad year for ringworm, spray harsher compounds such as formaldehyde or phenols onto rub areas (such as fence posts) where you believe the fungus is. These organisms are hardy and so complete disinfection in an outside environment is pretty much impossible.
There have been vaccines developed over the years. They are relatively effective but rather expensive and really only have a place in expensive show stock where owners want to minimize the likelihood of ringworm developing just before show season. Otherwise the vaccines don’t have much of a place commercially as there are many more fatal or production limiting diseases which we need to focus on in beef cattle production.
The important thing to remember is ringworm is more of a blemish than anything and can be treated. But be careful you don’t contract it, as the human cases are harder to clear up. I should know as I have had it once as a kid and twice in my 25-plus years as a veterinarian.