If I had to guess, I'd bet there's multiple factors that go into it, including both genetic and environmental ones. Some might have to do with care - eg two dogs might have the same coat type, but if one is getting a thorough blowout weekly during the hottest months and the other gets 1-2 a year, that'll make a difference. I also know that dogs, like people, can definitely acclimate better to high (or low) temperatures if they spend more time in that temperature range, so spending much of the day in air conditioning or a naturally cool place like a basement probably plays a factor in lower heat tolerance too. I imagine metabolism is the biggest genetic/physiological factor that's difficult to predict or measure and wouldn't be immediately obvious when looking at two dogs who seem very similar but have very different heat tolerances.
There's probably more subtle things going on as well, it's an interesting question! I'm not sure we even know all of the genetic/physiological factors that make some humans more or less heat tolerant, but it'd be nice if they figure it out. I'm miserable on both ends of the spectrum, haha!
There's probably more subtle things going on as well, it's an interesting question! I'm not sure we even know all of the genetic/physiological factors that make some humans more or less heat tolerant, but it'd be nice if they figure it out. I'm miserable on both ends of the spectrum, haha!