It’s better a week early than a day too late ❤️🩹 Definitely speak to your vet and be honest about your feelings and seek any and all advice/treatment that they have. It is not easy caring for a senior animal. You definitely work on their schedule not your own anymore.
In my experience, my family rescued a senior poodle. We had Joy for about 3 years and gave her the best life possible while she was alive. But once she was in our care, she slowly started to decline over those three years—went blind, deaf, vestibular issues, and developed cushings disease towards the end of her life. She had benign tumors due to negligence of never getting spayed, (we spayed her when she came into our care) but tumors eventually came back and were cancerous this time eventually spreading to her lungs. She had difficulty breathing, walking, and the cushings was really where she started to decline (they usually have 2-4 years once diagnosed.) Looking back—I wish we had euthanized her a little sooner. She was suffering due to our inability to let go, and once the sadness passes, I still feel guilt about waiting too long. It’s extremely hard when you love a pet, especially because they become your family, but it is a mercy at a point. Not an easy decision but one that many pet owners will unfortunately have to make. I wish you luck in your endeavors. It’s no easy thing