My sheltie is 15 years old, good coat, lots to bark, still running, but the last few days has not wanted to eat her normal food IAMS. So I started giving her cottage cheese, hamburger, and carrots (which she loves). Has no problem eating the carrots. But tonight would not eat her supper. She ate about 1/4 cup of food this morning. She is still drinking her water, but the last month is sleeping at least 19 hours (off and on day and 9 hours at night_ Wondering if I should try canned pumpkin or green beans. We have felt around her stomach and she doesn't seem to be in any stress.
We are on a very strict budget -only social security and I am afraid the vet bills would not be affordable.

Moved from fitness to dog area.

Of course my first suggestion for a pet of 15 years is to see the veterinarian to check for any underlying causes as to the lack of appetite.
Perhaps your vet could work with you on cost or there is a local group that can assist you with the bills. I would call different veterinary clinics and ask if they know of any such organizations in your area.
In the meantime there may be some helpful information here for you.
Anorexia