Yes, they can get too hot and they can die from the heat (many a sad story here on BYC). Panting (in this instance) means they are experiencing heat stress.
Fans
Fans
Did I mention fans?
Cold water sources (if you need to be away for hours at a time, put frozen bottle of water in a water bowl for them - it won't melt as quickly, and make sure it's in the shade)
Extra sources of water just in case their usual source spills or in any other way is compromised/
Cold fruit periodically (watermelon as mentioned, cantelope, cut up grapes, berries....)
Electrolytes when there's lots of panting (lots of info here on BYC about this - let me know if you are not familiar)
Shade
No heavy food in the heat of the day
JJ