Ringworm. We get it on some of the calves, occasionally on a cow. Although not technically caused by a "worm". It is a fungus and is frequently seen on calves late winter, early spring. It is supposed to be contagious but we find it seems to affect only a few in a group. Easy way to get rid of it is to "smother it". We use either an iodine solution put on with a "paintbrush" and really soaked into the skin; or use vaseline and smother the spot on the skin so that it is completely covered. They make other topical solutions for it, but usually one or two applications of the iodine and they are growing new hair in a couple of weeks.