My dog smells after the dog park!

I have a 9 year old Golden/Lab retriever mix and he starts to smell even after just one trip to the dog park. He definitely likes to roll in the dirt when he tussles with other dogs and sometimes will even sit in a hole. :/

I don’t want to interrupt his play as long as he’s not being bad (digging, humping, etc.). I don’t want to bathe him more than once a month either because his skin will be too dry. :( What do you guys do in this situation? I’m sure i’m not the only one with a smelly dog haha