Hot spots

Our 5.5 month old Golden pup gets hot spots whenever he gets wet (we think that's the cause)...if we can't get him 100% dry (which is often since its spring where we are and he loves to be out in the rain/dig in the mud). Any tips to avoid hot spots other than keeping him 100% dry? He had hot spots when we first got him and thought it was due to his chicken-based diet. He's now on lamb and hasn't had hot spots in 2 months until today.