We are only just starting to get into summer over here but there has been a few hot days. When we play with her she does quite alot ot running, and alot or running on a bean bag (which would be quite exhausting) and still no panting!!!Mine only pant if they are out back doing zommies for about 15 minutes. How hot is it where you live? how much does Fiddle run around?
Being a sc, she can dissapate her heat easy. I wouldn't worry. These dogs love the heat. I think they are adapted to high temps as they are originally from Mexico which is a lot of desert and heat.
I don't think these chis pant too much. They're cold natured & unless Midgie is laying out in the sun on a 90 degree day, she hardly every pants either.