[DukesMommy]

I agree with everyone else, he looks like a Yorkie! He's a cutie.
Unless you know the weight of the parents and can be a little hard to take a guess at what he will weigh as an adult.
Is the temp of your house warmer than what he was used to, so it might make him hot? Thats the only thing I can think of that would make him pant. You could ask your vet about his breathing