Shoot, I haven't had experience with that kind of thing. Hopefully, other members will see your post. I would bet most will recommend that you call a vet, though. It could be dangerous to guess.
That said, how old is your pup and how much does he weigh? I've heard of YTers recommend Nutri-Cal (a high-carlorie paste that comes in a tube) for hypoglycemia, but I have no idea if that's what you're describing. My first thought was dehydration with the panting.
I just found another thread with a similar description. Check it out:
http://www.yorkietalk.com/forums/showthread.php?t=8903
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Mike ~ Doting Dad to Jillie, Harper, Molly, Cooper, Eddie (RIP), Lucy (RIP), Rusty (RIP) and Jack (RIP).
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