Always very sad to have sick or dying pets, I've had both.
First, was very sick, couldn't,wouldn't eat, liver not functioning. Was operated on to fix liver problems, plus 6 tablets to medicate to an animal not eating.
Was decided to go back into theatre to place a feeding tube directly into the stomach.
So every day for 3 months had to mash all the food and mash all the tablets into a water goo and syringe feed her twice a day. It took a lot of work to get her back to health, by the way the vet suggested to put her down as the rate of success was very little as she hadn't been eating for weeks (well weeks before we noticed she was thinning) and was extremely weak to begin with.
After two months of tube feeding, she finally started to get some weight back so tube was removed and started mouth syringe feeding to try and get her to eat on her own ( which she didn't ), so the vet suggested we try a human drug to help her appetite. Only took another 4-5 days on the appetite drug and she was eating on her own. That's was 5 yrs ago now and she's still going strong.
Moral of the story is don't give up on them if you don't have too.
Good luck with it all.