I believe euthanasia is good to put an end to a dog's suffering from a terrible illness. I know this from a personal experience when my family and I had to make a tough decision to put down our dog, so she wouldn't be in pain anymore. It was a sad and tough decision, but I also think it was for the best. I do not like the idea of it being used to put down dogs that owners no longer want to take care of, especially since they could find a little kid who wants a dog and the parents don't mind having a dog.
I am CVT and have been doing veterinary technician work for almost 20 years know. Euthanasia allows a pet guardian to end the suffering of a beloved pet. For most people this is only done at the end of a pets life to put a humane end to a terminal illness. I do not agree with people who euthanize pets "for convenience," these are the "owners" who have their pet euthanize because they no longer want to care for them. As for the method...Fatal Plus (or any other barbiturate overdose) is very humane. This is just an overdose of anesthesia. I am not a proponent of using CO2.