Dog with Vestibular disease

I'm copying this here from new user Sanita (Susan). She has this question:

Hi everybody,
I'm looking for some help or advice. I have a 16 year old basenji mix. He got very sick Monday afternoon. Vomiting,couldn't walk, his head is tilted and his eyes were moving quickly back and forth. I rushed him to the vet and she diagnosed "vestibular disease" I've been giving him the anti-nausea medication and an antibiotic. I have to give him fluids ( pedialyte,and chicken broth) by mouth with a big syringe. Supposedly is the disease is in his ear and not his brain he should improve within 4 or 5 days. He still can't walk without falling and walks in circles, his head is still tilted. I got him to eat a little boiled chicken breast ( about 1/4 cup) yesterday. I have to carry him outside to urinate and he only does that once a day in the evening. Have any of you had experience with this. He doesn't seem to be in pain, just very disoriented. ( He looks like he's stoned or drunk) The vet has mentioned euthanizing him which is an option considering his age, I just want to give him a chance to recover. Any advice or help is greatly appreciated. We rescued him when he was 9 months old from an animal shelter. He had been adopted and returned twice. We didn't even have to pay the adoption fee they just said " Here you go, please don't bring him back!" He's been a good dog for many years. Maybe it's time to let him go. It's going to be very hard to do.
Thanks again,
susan