Several years ago on one of the first days in our new home our boxer went out at 5:00 am to check out the strange animal in the yard. Of course being a dog, he had to try and sniff it's butt....
We didn't have anything at the house to clean him up, except dish detergent and shampoo but we did wash him down pretty well in the shower. We went out later that day and stocked up on the H2O2 and baking soda and never had an issue again.
The only variance on the recipe that Mike posted is we used Dawn dish washing liquid because it helps with the oils.