Most of the critters I have been present with when undergoing the procedure slipped peacefully away. So much so, that I encouraged my sister to come when we put Kitty down. Uhg! She was wasted when they finally diagnosed her with diabetes, and we still tried the insulin, but Kitty got worse.
Anyway, it was hard to get it into the vein, and then she wasn't dying. And she wasn't dying. They ended up having to stick her again. It was pretty awful.
On the whole though, and I am always there with them, telling them what a good dog they were, and so on, it has been just fine without a separate sedation.
Seniors: Jenna & Babs, Heidi, Odessa
Mature Adults: Milla & Ninja, Joy, Bear
Adults: Hepzibah, Karma, Cujo II, Lassie
Young Adults: Quinn
Puppies: Ramona, Kojak