Not counting of course if that horse wants to drop a load. My concern would be passenger safety and I would refuse to allow that animal on my plane, right up to the point where corporate said I’d be fired if I didn’t allow it on board. It’s still a safety issue. AA once allowed a pig onboard that wound up running up and down the aisle.
My concern would be passenger safety
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You would think that the airlines would be fearful of lawsuits. Its bound to happen.