I can relate Flotsom, put our old Shepherd/Retriever mix down 2 years ago. I can still remember holding him as he tried to jerk away from the poke of the needle and then he faded off. His eyes drooped closed and he hung limp but it was for the best as cancer and hip dysplasia had really taken a toll on him. We had gotten a Shepherd mix the year prior and he'd gone downhill ever since, with the new puppy he was the old man and he showed every sign of it.
Our cat of 13 years is probably soon to go as well, and another one of the dogs is getting on in years as well. Seems you never spent enough time with them when their gone.
All my best for you and your daughter, Red.