I’m sorry you’re going through this. It’s very hard and painful when animals get old and start having such problems. I’m very much AGAINST animal euthanasia because the procedure itself is very painful for them, even though veterinarians will deny it. In some cases, it can cause an effect where the animal drowns in its own fluids as blood enters the lungs — an extremely painful process. In addition, there are paralyzing agents that make the animal unable to make any sounds during this time. So it can become a great suffering for the animal lasting from 30 minutes to an hour and a half. I would absolutely never subject an animal to something like that, no matter how bad things are.
You can give it unconditional love and also use Reiki energy — set the intention for it to work for the animal.
It may not help much for such an old dog, but at least it can ease its symptoms a little.