I did it a few months ago and all I needed was the bill of sale and the list of current vaccinations from the vet. No problem. Call the Canada Customs office if you're still not sure.
Be advised, though, you cannot take dog food across into the U.S. (or treats). I took some and the customs agent let me go but warned me not to do it again.
We bought our Sophie in Michigan..the border is about 5 mins from my house and we go across all the time. Just make sure you have her pertinent paperwork and you'll be fine.
__________________  VAL, TOPHER AND SOPHIE |