The doggy, a breed with physically restricted nasal passages, was clearly stressed by being alone in a dark environment, but hypoxia or asphyxia is a relatively painless way to go. There was a gradual loss of oxygen. You pass out and expire. It is not like physical suffocation, such as strangling, or even drowning for that matter. Who knew the overhead compartments were air-tight anyway ? Or are they not air-tight ?
And if they are air-tight, why ?
