In 1988 I moved from Boston to Seattle but left my macaw, Betty, with a friend in Boston along with a basic Plano pet carrier. On the day my friend entrusted Betty to United airfreight at BOS/Logan, United called to inform me that -- Oops! -- when they went to load Betty on the flight to Seattle, the Plano carrier was empty.

Theft? Stupidity? I can't guess. But just a data point for anyone who might think of putting a pet in baggage/cargo that might have any monetary value.