Not wanting to add any sorrow to your situation, but there are alternatives to euthanasia. I know how painful seeing a pet suffer is however.
My beloved cat got sick and died in the night peacefully in our house after 13 years. But I believe he died happily and not in any severe pain. That was in 2005.
But before resorting to euthanasia, if you can afford it I urge you to consider treatment options. I wish there was hospice care for pets because from what I understand they become very terrified when actually being euthanized, and I could not do it to a pet of mine just for the final trauma. If it came down to it, if I had a firearm or a syringe of morphine or some other means of swiftly and painlessly ending the life of my pet at home, and not in a vets office, I would do it that way.
I hope this post doesn't add to your suffering at all and I feel with your pain immensely. So please don't take offence at all, I just want to encourage you, if you can, to look into alternate treatment options or, if your dog is in agony and can't be treated, a more humane approach than the vets office. I wish vets would at least make house calls for euthanasia.
A few years earlier by the way we took our cat to a vet. The first doctor said he had feline AIDS or infectious peritonitis and wanted us to put him down. The second vet, a caring woman, lovingly took him out of his oxygen cage and listened to his lungs and determined he had highly treatable asthma. I bitterly,regret not taking my cat to the vet for diagnostics in his third illness, except by the time we found him he was so sick he might have perished in transit.
So, I pray for you, your dog and your family. Kyrie Eleison, Kyrie eleison, Kyrie Eleison.