((HUGS)), I'm so sorry for your loss. Different vets seem to have different methods. I've been present for the euthanasia of a few small pets and generally the method used was either an injection or an oral medication to induce anesthesia, followed by the actual euthanasia. The last time I had to have one of my hamsters put to sleep gas anesthesia was used and I was not allowed to be present at all, which was worse emotionally for me, I think. To this day I have guilt that I wasn't with her. Please know that even if the first shot was a pinch, it would have been really momentary, and would have been more a surprise than real pain.