(Reuters) - Two. U.S. senators on Thursday unveiled legislation to explicitly bar airlines from putting animals in danger by placing them in overhead baggage compartments, after the recent death of a puppy on board a passenger aircraft.

Senators John Kennedy, a Republican, and Catherine Cortez Masto, a Democrat, said the legislation would direct the Federal Aviation Administration to create regulations to prohibit the storing of a live animal in any overhead compartment and to impose civil fines for violations.

The bill was prompted after a puppy died during a flight earlier in the week, after a United Airlines Co cabin attendant ordered that it be stowed in an overhead bin.

The incident spurred an apology from the airline, which said it would assume full responsibility.

The bill is titled the Welfare of Our Furry Friends Act, or the “WOOFF” act.

Kennedy, in a letter to the airline on Wednesday, said United’s “pattern of animal deaths and injuries is simply inexcusable.” He cited figures from the Transportation Department that showed that out of 24 animals that died on U.S. carriers last year, 18 were on United flights.

The U.S. Transportation Department “is looking into the circumstances” of the dog’s death, an agency spokeswoman said Wednesday.

The airline’s animal troubles compound a public relations nightmare triggered a year ago, when a male passenger who refused to give up his seat for an airline employee was dragged out of his seat and down the aisle of a parked United plane.

Congress has since been considering new passenger protections. Bills introduced last year would make it illegal for an airline to bump an already-boarded passenger from a flight and require airlines to promptly refund passengers if they do not receive the service they have paid for.

The measures are expected to be considered later this year when Congress votes to reauthorize the Federal Aviation Administration. One bill would require the FAA to set minimum seat sizes on U.S. airlines and a minimum distance between rows.

United said that by April, it would issue brightly colored bag tags to passengers traveling with in-cabin pets to help flight attendants easily identify the animals.

The airline claimed earlier this week that though the puppy owner had told the flight attendant that there was a dog in the carrying case, the attendant either did not hear or did not understand there was a pet in the bag, and “did not knowingly place the dog in the overhead bin.”

That account appears to contradict a statement from a fellow passenger, Maggie Gremminger, who wrote in a series of tweets that the woman wanted to keep the dog in its carrying bag under her seat, but the flight attendant insisted she put the animal overhead.

Several high-profile incidents of animal deaths and misplacements on United flights have plagued the airline over the last year, including the death of a giant rabbit on one of its flights last July and a dog that died in a plane cargo hold in August.