Getting our 15 year old dog to eat

Question
I have a 15 year old golden retriever mix and she is very picky with her eating. She has lost at least ten pounds because of her poor eating habits. The problem is that she won't eat hard dog food anymore and rarely eats canned dog food. She eats probably once a day or less and sometimes she will only eat if the food is hand-fed to her. I cook different foods for her mixed with things such as rice so she does not get diarrhea. She'll like something for around 2 feedings and then refuse to eat it again. I've tried to feed her pretty much anything I can think of to get something in her stomach so that she at least eats something. These things include lunch meat, hot dogs, pork chops, bacon, etc. My sister is a veterinarian technician and my dog has been in for a senior wellness panel including her blood work done. As far as I know everything has checked out to be healthy with the vet. They said she is in good condition for her age, except for her arthritis which she takes Deramaxx for (50mg/day). How can we encourage her to eat?

Answer
What kind of shape is she in?  Evaluate her using http://www.longliveyourdog.com/twoplus/RateYourDog.aspx  Unless she is still overweight even after losing 10 pounds, I am not sure what else to do.  Nearly all cases of dogs not eating are from being sick or over fed.  If she is neither, I guess you just keep trying the rich food.  It is very difficult to maintain the complete and balanced diet dogs need except by feeding a commercial dog chow.  In this case, you may not need to be concerned about the long term effects of a poor diet.  You need to keep getting some calories in her to keep her going.  

I have heard of vitamin E injections to stimulate appetite.