After a painful registrations and losing my long message, here i go again for the sake of the dogs: IT IS THE FOOD!
Before taking your pet to the vet, give her brown rice and cooked or raw (better) chicken, the appetite will come right away and will drink normally. Try it, it does not matter if for a day has loose stools. She will get well. Comercial dog food is poison has GMO corn and soy, among other poisons. No matter how expenssive the food is, it is unnaturally processed, and it ruins their kidneys, liver and nevous system.
Add to the brown rice and chicken some peas and sweet potato. Trust me, just try it. If this does not work, THEN you take her to the vet. Nature must be the first approach because we are ruining our pet's health as we have ruined ours. Good luck.