United had a top series of animal deaths and injuries of any U.S. airline in 2017, based on Department of Transportation data. Out of a 24 pet deaths that occurred aboard U.S. carriers last year, 18 were on United flights. The airline had 2.24 “incidents†— definition animal deaths or injuries ― per 10,000 animals transported. American Airlines had a subsequent top occurrence rate, with 0.87 incidents per 10,000 animals transported.
Article source: https://www.huffingtonpost.com/entry/united-airlines-dog-japan-missouri_us_5aa949dee4b0004c04067a57