My Great Dane would kill over in 30 minutes with no A/C. The best, smartest dog I have ever had, but he is, shall we say, climatized and spoiled. He is scared of dang near every animal put on this Earth. I originally got him for hunting hogs, he got sprayed by a skunk when training as a pup and has never been the same since. He has discovered the couch and A/C is less stressful.