they just dont get thrown with the luggage,theres a special spot down there that is pressurized so they can breath! Its not pressurized where the luggage is,like i said theres a spot underneath for animals.
I've never had a bad experince flying with animals,i've been flying with them since i was 2 years old.I've only flown with my dogs and cat, with Air Canada and Lufthansa,and they were very good to us.