We are on the Canadian side and travel with our dog back a forth to the US many times a year.
As was stated have an up to date rabies vaccine and certificate from your vet stating the dog is in good health, you should have no trouble.
The only time I've seen a hold up if the boarder crossing guard feels the dog or dogs are being mistreated or look in poor health.
I'm sure that wont be your case
Cheers