JRT rolling around in other animals waste

Hi, my question is about my 9 month old JRT rolling around in other animals droppings. We will be playing catch at the park and he will just stop and get it all over him. He will also do it when he goes out in the back yard. I live in a wooded area and have not found where these droppings are, but sometimes I have to bathe him twice a day. He likes to get it around his neck, that is the most common spot where I find it. Your help is needed, the only solution I can think of, is not to let him go out by himself, but what about when we are playing catch?