Bonnie doesn't do heat well either. She will lay on my lap for as long as she can stand it then jump up and run to the tile on the fireplace to cool off. She pants too.
I keep Bonnie's belly shaved so she can soak up the cool on the tile. Also the concrete in the garage is really cool, no matter how hot it is outside.
Last year I purchase a cooling mat. It is kind of thin, and you fill it with water. Not a lot of water, cause the jiggling would freak most yorkies out
. I put an old pillow case over it, the cotton is cool too.
Ice cubes in the water dish also. Hope this helps