I started wiping mud on my shins and arms where Poison Ivy will show up - and all too often. Also spread mud on my shoes. It doesn't need to be a lot, just so when I wash the mud off at the watering hole/dog-swim area (or my water bottle), the oils wash away with the mud.
Having said that, whenever I forget to do this, my girlfriend gets mysterious itchy 'bug bites' on her arms & legs...& I just act like we gots a mosquito problem.