My 13 year old Tibetan Terrier has always been a fussy eater, Now she is eating less and drinking more?

to be honest with you, if you have been to the vets, and they have told you whats wrong with her and already given you medicine, but your still not seeing any improvement, the only thing you can really do is just follow your vets advice, i dont want to sound rude, but she is very old for a dog, and some times, as a dog gets very old, they just lose their appetite, and give up on eating, you can still try to get her to eat as much as you can, but if she isnt going to eat, its becuase she knows there is a problem, she isnt just not eating for fun, she knows she is getting old, and is probably just letting nature take its toll.