My little grandson, who lives in New Zealand is terrified of dogs. They have their own dog, a gorgeous white Labrador (who incidentally when she travelled to New Zealand, had to travel in the hold, or some other place away from passengers. I know there was someone to look after the animals as on a long flight they need feeding and toilet breaks) and my grandson is fine with their dog, but terrified of other dogs. And I mean terrified. He suffers from very bad anxiety and if he got on a plane and found a dog nearby, he would be extremely anxious. There should be no need for a situation such as this to occur if animals don’t travel in the cabin.
Re unpleasant passengers, I do agree with MissInterpreted in that we cannot control who we are next to on a flight. I remember one a time when my husband and I were flying back from somewhere in Europe, and it was before the time when you could select your seats online, and when we checked in at the airport, we had to sit apart. My poor husband was between two other passengers and one of them stank to high heaven. I could smell him from the row behind and across the aisle, but my poor husband! Luckily the flight was only a couple of hours, but imagine that. And there’s nothing you can do about it.