United Airlines says it's taking responsibility for the death of a dog on a flight from Houston to New York this week. A United flight attendant said the small dog in a carrier had to be put in an overhead bin. It didn't survive the flight. United said it was a tragic accident that shouldn't have happened. It also gave its condolences to the family, and said it would investigate the incident. United has had other animal deaths recently, including a dog in August and a giant rabbit in April.