does/did

A man walks into a shop and sees a cute little dog. He asks the shopkeeper, "Does your dog bite?"

The shopkeeper says, "No my dog does not bite."

The man pats the dog and it bites him.

"Ouch!" he says, "I thought you said that your dog does/did not bite."

The shopkeeper replied, "But that is not my dog."

Should I use 'does' or 'did'?

Thanks.