I recently got into an offsite discussion about flying with pets in the cabin and what would happen in an emergency on board. I brought up the fact that United Airlines' pet policy states, "In the event of an emergency, oxygen service will not be available for pets." Southwest has a similar phrase in their pet policy, though I couldn't find anything similar in American Airlines' or Delta's pet policies.
Beyond oxygen service, I was arguing that if an evacuation took place, I wasn't aware of any procedures for getting a carryon pet evacuated safely. I said that the human lives of the other passengers on board would take precedence over a pet. To my knowledge, pets in carriers are essentially treated as a carryon bags in the cabin. I also hypothesized that letting a pet out during an emergency could be extremely dangerous and would likely invoke the ire of the crew, if not get you into legal trouble.
TL/DR: The discussion left me wondering are there actually any procedures for getting carryon pets out of the cabin in an emergency? This is mostly directed at pets that would be in a small kennel and stowed for the duration of the flight under the seat in front of you as a personal item. Are they considered carryon luggage, which should then remain stowed (as awful as that sounds), or treated like infants? Have there been instances of serious accidents where carryon pets were also evacuated in the past?