[cinnamonmon]

I have a 3 yr old Yorkie who has a variety of odd symptoms which I am very concerned about. I have posted about at least one of the symptoms before as an isolated symptom but wonder now if they are all related.

She is very sensitive to even the slightest heat...even at say 70 degrees, she becomes over heated and if we walk around a small block, she is panting like crazy. The thing is, then she will continue panting the rest of the night, even after being in an air conditioned home. Of course, the hotter it gets the worse it is.
I noticed this last summer too and actually took her to the vet who blew me off and said, basically, "some dogs pant more than others." H
e listened to her heart and the usual basic exam and didnt find anything. I felt stupid
She just seems like she cant get comfortable when she is trying to sleep either, flipping from side to side. She always has breathed faster than normal, but lately its worse than usual, even at rest.
She doesnt seem to have any energy anymore either, she's only 3 and never wants to play, and basically except for the one walk a day and eating, she seems to lay down all the time. My other two dogs are 6 and 10 and have much more energy than her. I want my fun little girl back who would sit at your feet with a toy till you paid attention to her.
She is overweight, a little. The vet though said though that he would only want her to lose a couple of lbs if she lost...he did not think she was badly overweight. I read somewhere about how you tell if a dog is fat, and she doesnt really fit that criteria...she is just solidly built...about 8 lbs.

I am wondering if it is the extra weight, maybe its worse than I think which could be causing the panting or lack of energy. Surely a 3 yr old dog should be more playful than this. Last year when this first started I did get a second opinion from a vet who did $200 worth of blood work and found nothing wrong. Im a nurse and it seems to me symptoms like this could be related to heart problems too....I just dont know.
I may be over reacting and I sure cant afford wasted vet bills again, but it just seems like this is not normal. I will say except for these symptoms she seems like herself...she eats well, is eager to go for walks, (though she has not stamina) and drinks without problems.
So what do you think...is 8 lbs hugely overweight...enough to cause these symtpoms? Is this anything else you can think of that would cause this? I am so worried about her.