If you have concerns about having to potentially put down a pet, find an at home euthanasia vet, IMO it's the best way to deal with this process. Having animals be able to see and smell the death happening helps them understand, you don't have to worry about transporting an animal in rough condition, and having them in a familiar environment when it happens makes it far less stressful for them. Last year, I had planned to have my dog put down a few weeks after his health started really declining, but when it was obvious that he was in unbearable pain, the vet agreed to come out later that day, on just a few hours notice, no questions asked.

The dog was very closely bonded to my two cats (who themselves are a bonded pair of litter mates) and having the dog euthanized this way allowed the cats to understand what happened. They were pretty distraught afterward (as was I) but weren't looking for him around the house. Their personalities changed in that they were more stressed out when I had company at the house, and didn't really return to normal until I adopted another dog about a month ago that they were able to bond with in a really similar way. Because of how closely the cats are bonded I definitely will need to use one when the time comes for either cat.

I really don't know how someone could deal with putting down animals all day, but if you can find a good one they are fantastic. In addition to helping my cats, it definitely helped me process the situation way better than if it had been done in a sterile setting at a vet's office.