How is the pup now? This is great advice and I was about to type the same thing before I read this reply. I always carry water and don't work my dog after 8:30 am or before 8 pm in the summer. Day time is for play, sleep, and pool time - too hot here in the summer for work.Is this pup ok? He looked so hot and stressed I can't stop thinking about him. Five minutes should NOT do this!
Once you let an animal overheat it does something to their metabolism to make the "next time" more likely. And like Carmen said, puppies not so good at regulating (neither are seniors)
Next time he gets hot the best thing is to take a garden hose, run out the HOT water first on the ground, then aim it on lower belly and between back legs until he starts to cool. Then STOP as they can overcool as well. Usually if mine is panting and the tongue is back to normal* I stop. Don't overcool the neck because that can send the signal to the brain that a hot dog is cool when it is not. Overheating can do awful things to blood chemistries.
I always carry cool packs with me when we have to work in heat (the kind you break something inside and they get cold) and can wrap them in a wet towel......I have not needed them because I force my dog to take breaks in the shade, but have emptied water bottles on my dog's inner thighs when we got back from a July search.
*I do have a thermometer but the tongue is a good indicator. This is a good article
Dog Overheating | Outdoor Life