I don't get overly stressed about it, but do try to discourage it. Remember that dogs are flexible and have long tongues and clean themselves...I don't really like the thought of them licking me after clean themselves after a poop...much less my kid

However, don't stress, just try to curtail it until the child is older, then he will just move the dog away with his arm. Make sure you do regular dewormers! I do this twice a year, even with Interceptor etc. on a monthly basis. Just to be safe.