So sorry for your loss of Copley.
This is Paisley who turned 9 on 2/26/23 and we lost her on Tuesday 4/4/23. Almost the same scenario, she was fine then all of the sudden on Saturday 4/1/23 didn't want to walk which wasn't out of the ordinary since she was her own girl and only did what she wanted. We did notice she appeared to be limping a little so thought it was a rear leg issue.
The soonest we could get her in with the vet was on 4/2/23. I woke up that morning and she ate and walked ok but seemed a little unstable on her feet.
My wife took her in and when getting to the vet Paisley just collapsed on the floor. Checked her gums and they were pale, did an ultrasound and she had a tumor in her spleen which was bleeding into her stomach. The vet provided an option for emergency surgery about 30 miles north. They would first do a cat scan $1200 dollars to see if it had spread then could do a surgery for $10000.
I drove up to the vet and we decided to try at least the cat scan, carried her out to the car and then took a deep breath. We had another golden Baylee (12 1/2) who we lost in 7/21. He was a tri-paw due to a benign tumor above is back right knee, which was removed when he was 4. In 2/21 we discovered he had melanoma on one of his left back leg toes. We removed the toe and did some sort of new cancer vaccine. At the time of the toe removal, the cancer had not spread, so we went ahead with the vaccine application which was a total of 4 every 2 weeks. In late 6/21 my wife noticed Baylee had labored breathing so we took him in and cancer had spread throughout his organs. It turned out the vaccine wasn't effective until 8 weeks after the last treatment.
After talking through what Baylee went through, we talked about how fair would it be to Paisley to put her through a cat scan, surgery and recovery. If she even made it through a surgery, how happy would she be or would she just be miserable and not do the things she loved: walks, bubbles in the backyard, rolling off the sofa, wresting with her sister Ivy.
We decided to let her go and I carried her back in. It was so tough because she was alert and her normal self. We showered her with attention and she went peacefully.
The picture below was taken on 4/2/23.
View attachment 902934
After letting her go, we had all the same second guessing. What if the tumor was benign, she was the 1 in a million survivor and had 5 more years to live, did we miss any early signs of a tumor, etc...
In the end we just took solace in she didn't suffer and we did the best for Paisley and I think you made the best decision for Copley too.