Pandora - I agree!
About 20 years ago, I took two cats on a domestic from LHR to IOM on a Viscount. This a/c had a luggage hold in the tail that was accessible from the galley in flight. Animals were stored in there.
Upon boarding, we had agreed that we would be able to check on them during the flight. Two VERY unhappy cats. The poor things were cold, despite the blankets and hotwater bottle, as the (promised) heating seemed non-existant. The noise and strange change of altitude all in darkness.
We had to take them with us due to a number of reasons but we never did so again.