Ring worm isn't a worm, don't know how it got it's name, but anyway it is a fungus. It will stay in the wood and ground so once you get it, chances are pretty good it will re-occur. It won't affect fertility/health but it is ugly. Also once there is an outbreak chances are pretty good it will go thru your herd. It is hard to get rid of but can be done. Just depends how much time and energy you are willing to give it.
You can treat your facilities with bleach. Clean the barn and put about 1/2 and 1/2 bleach to water,put it in a hand sprayer and spray it on your walls and floor. (If you use halters and grooming tools clean them too.) I have heard of folks that even put the bleach solution on the animals, I haven't tried it nor seen this method. Not sure I would try it, seems like it would burn their skin.
To treat the animal again, depends on how much you want it gone and are willing to do. If you have a large herd with it, realistically what I have done to rid this crap isn't going to be something most would/could do. But since we show our animals (where we picked it up by the way) we don't want it to spread if at all possible to contain. So this is what I do with the show animals. I use a curry and rough up the spots, then I use the iodine anti fungal shampoo (any brand will do, can get it by the gallon from Jeffers) if the weather is decent I rinse the animal, if cold just use a rag and spot treat. Then I use the Jeffers anti fungal pink spray (Sullivans has a good product too, but costs more) and spray each spot. I do this every day for 10 days! It is a big pain in the backside but it works. There have been a few that I had to treat longer than the 10 days but generally that is how long it will take. Once hair is growing back into that spot, you have won. The spots around the eyes are harder to deal with but like I said these are show animals and usually will cooperate but sometimes I can't spray without getting it in their eye so I put the stuff on a rag and rub it on the spot.
Be sure that you clean your hands after handling these animals or you will end up with it too.
This is probably more information than you wanted!
