Since we take our doggie to the desert southwest for our yearly vacations, and, being a black dog, she really suffers in the sunlight...
I made a 6-pouch 'doggie hydro-pak' for her... A sort of "backpack" with 6 pockets, 3 on either side... I take along 4 small plastic bottles - the pockets were made to hold such bottles comfortably, and chill or hopefully freeze them in the motel room's tiny freezer the night before... I use the other two pockets to carry a collapsible water dish, and poop bags...
Since the backpack is made of 100% cotton, I can soak it with water before we take off on a hike. It covers most of her body, especially her back, with the white fabric. Soaked with water, and with the frozen or chilled bottles in the pouches, she can handle most days of extreme desert heat... Her paws handle the heat unless we're on black asphalt... She and I walk around the neighborhood a lot, even during very hot days, which keeps her paws calloused. But a set of 100% cotton canvas doggie booties might be a pretty good idea, too!!
I have purchased doggie booties in the past, and they're pretty simple - just a very long rectangle sewn together on 2 sides to form a bag, with a specialized velcro closure... I've salvaged the velcro closures (they're a combination of velcro with elastic...) to use on future home-made booties... There are several web sites that sell doggie booties, and after you've bought a set - and if you sew - you can make your own in future...
Zid