Thanks for the advice yall. Djhogdogger my friend lives on the eastern part of New Mexico and hunts the TEX-New Mexico border thru the sand dunes.
im no weather man but i think the temp drops quite a bit in desert area. thats probably why he can be so picky about the temp.
i say just get your dogs in shape and keep their body fat to a minimum and work them in the heat so they can build up a tolerance to it. when i say work them i mean do something like run them around with the 4wheeler but be careful and bring plenty of water or work them next to water. start slow and make it tougher each time.