Pain and the dog

My Dibbs is now 12 years old. She is a Chow-Collie mix and has been foster mom to many , many puppies. She has been my constant companion for all this time minus 6 months - that's how old she was when I found her. This beautiful puppy was directing traffic on the road in front of my house. This is a busy road, through traffic and all that. Cars were stopped coming and going and every now and then a horn would honk. Like that's gonna make the puppy know what to do next! I was in the front yard with my resident dogs as we were watching this drama unfold. Long story short, she has been with me ever since.
This wonderful dog has never met a stranger. She has worked with children at libraries to show them how to approach a strange dog. She has visited Nursing homes and Hospice patients. She has been in 13 Christmas parades and walked for Hospice, Diabetes, MS, any cause that excited me at the time. She was always game.
Dibbs has never growled at another dog unless that dog growled at her first. She has never attacked a dog, though she will defend herself. She does not bark a lot and when she does, I go and look why. She has been my best Buddy for such a long time.
Over the last two months I noticed that she seemed to have trouble getting up. She is getting on in years, a bit of arthritis perhaps? All my dogs get Glucosamine every day with their food, as much to prevent pain as to help treat it. So I didn't really see that this would be bad. HA! The vet check up showed nothing but low thyroid levels. OK. This did not explain why she suddenly refused to eat her dinner. We started on some thyroid meds and will check again in a month.
One week after her check up Dibbs could not let her left hind leg touch the ground. It was kind of dangling there. She had a lot of pain as evidenced by all the panting and the refusal to get up and go outside. Of to the vet we go! X-rays showed major arthritic changes in her spine, hips and knees. There is a loose ligament in the left knee, that's why she can't put weight on it. More meds - this is the second day on some major pain meds. She is alert and cares about what goes on around her but it takes a major effort for her to get up and go someplace. And she does not want to take the meds! I have tried cream cheese (no), Braunschweiger (no), came up with liver pudding (will see for how long). Problem is that I just started giving her Denestra - this needs to be given 1 hour before everything else. The Thyroid med needs to be given 1 hour before other things as well. I e-mailed the contact on the Denestra package but they haven't responded, this is 4 days later. Can I give the two together? Until I know better, I am giving meds every hour on the hour! After the last single med has been given I can feed her something and make her take her pain meds. Right now all she wants to eat is Peoplefood for Dogs - Chicken, Sweet Potato and Oatmeal. Fine with me!
Today seems a little better, she isn't quite as reluctant to get up. Maybe the pain meds are accumulating in her system and working better? I hope so.
We were going to walk in the Christmas parade this noon but it was canceled because of the lousy weather. I am glad. I don't think I could have gone there without her.