After working with animals most of my adult life, I can say with out doubt. Which ever you chose is the best thing. As long as your beloved dog is with you every step, she will do what she can, until she can not. I have fostered, and rehabilitated so many dogs before my kids came along. Some of them I had for only a short time and some became my pets. There were a few that stuck with me in my mind for a long time. Its never easy to make a decision that requires you to end a life.
One was a basset/lab mix named Rain. Rain was one of the saddest, heartbreaking cases I ever had to go on in a neglect call when I was working for a Humane Agency in my state. A couple got Rain as a small puppy. They couldnt seem to house train her right, and so she stayed in her kennel. All day, every day, sometimes laying in her own filth and pee. After she started stinking up the house, they put her in a shed in the backyard. She was lucky to eat daily, sometimes maybe 2 times a week. She had a large rabbit bottle of water and sometimes that was filled sometimes not. She passed her first 2 years of life this way. Only getting out of the kennel for them to scrape poop out and spray it with some water. Then to be shoved back in for weeks. They had a bonfire party one night, and she was barking. So they poked her with burning sticks from the fire.
Some one there felt bad enough to call. We took her from her kennel. She was terrified and aggressive. I muzzled her and carried her in the car. We saw what years of being in a small cage had done. She had chewed her own toes off both her front feet. Her back legs were so weak from never getting up or walking, her hips were deformed, and so she was only able to drag her back legs along. She had burns all over, horrible ear infection, and three rotted teeth. She weighed about 20lbs. Vet estimated she should weigh 55. Everyone said, put her down, put her down... while she laid in my arms trying to eat me (not in the nice way) I just felt this dog doesnt deserve that! I paid to fix her to the vets best ability. I did physical therapy every day. Swimming, walking with a towel around her hips. She was able to regain the ability to walk, but she was a emotional and behavioral mess. I stuck with her for 4 more years. She was never my favorite dog, heck I didnt even really like her as a dog, but I LOVED her if you understand that. When my kids were born, I was scared she would be too aggressive for them, but she surprised us once again. She disliked my husband and I, but babies and kids. Completely different animal. Sweet, protective, loving. One more year passed. She was growing on me, when I noticed something growing on her. A tumor. She had cancer, and had spread through her whole body. When we got the prognosis of what we were going to have to do, it was grim and expensive. After a LONG discussion. We decided to make her comfortable, give her pain meds, and let her pass on her own. When the pain meds didn't seem to cover her problems any more we decided to put her down. On the table, for the first time since I got her, she lifted her head, she licked my hands and face, and she wagged her tail. I honestly think she knew what we were doing and she thanked us for it. It was peaceful, quick and I didnt feel as much guilt as I thought I would. She will always be in my heart and head forever. She didnt have to be super dog for that.
Its a very hard decision. You have not taken it lightly, you have weighed the options. She is ready to go. I want to be clear, that sometimes they do do things unexpected during the procedure. There will sometimes be tremors, crying (yelping), residual breathing, and movement. It could happen, and for some, it can be traumatic. Usually its just they fall asleep and that's it. I just want to prepare you for it, cause the sedative they give generally makes them sleep before they expire, but sometimes its not always the case. I have been on hand for more euthanasia than I care to count. I have seen almost everything....