I wish people would exercise a bit of common sense and refrain from taking their dogs out on arduous hikes.
While some breeds such as huskies are known for having a high degree of stamina, many other breeds, even large breeds, do not.
In this case, the guy’s mastiff was overcome with exhaustion and simply refused to continue. In this case there was a happy ending, but it could have ended badly.
Next time, leave the dog at home.