The rescue group I volunteer for (Katie's Place) only euthanizes when the animal can no longer enjoy a good quality of life. They authorize euthanasia on the advice of their vets (who are with veterinary hospitals in the community). The euthanasia is always done by the vet, and 90% of the time a volunteer is there with the animal. I have only attended a couple of euthanasias but the animal was always sedated and given a few minutes for that to take effect.
For myself, I believe you cannot call yourself an animal welfare organization or shelter if you euthanize any animal who could be saved with reasonable vet treatment and reasonable care. How is that "sheltering" or "welfare"?
Brigitta MacMillan