Poor you!! Is Luna your greyhound Paula? I remember some years ago when we had Penny, she had a mysterious illness with terrible runs, and she spent a week at the vets. She was never quite right after that. She came home looking like a skeleton. I was shocked!..I mean, they're thin even when they aren't ill! They never really got to the bottom of it. We stopped feeding her her normal greyhound kibble. We were feeding her loads of fish and rice, chicken and rice and scrambled egg in the morning. They have such finely tuned digestive systems. Arrowroot powder mixed into her water is great for their upset tums. But I expect you know all this anyway....hope there's some improvement soon love.