Severe intestinal parasite infection can cause weight loss but not an increased thirst. Vomiting, weight loss, and increased thirst can be signs of kidney disease, liver disease, diabetes, or chronic pancreatitis among other diseases. Your dog needs to be examined by a veterinarian and have some diagnostic tests run.
Thank you for the answer. As I have 4 other dogs taking this one to the vet is going to have to wait. I was how ever hoping to some way to help her with out going to the vet. cathy
A dog that is losing weight and can not keep food down needs to be seen by a veterinarian. Having 4 other dogs should have nothing to do with the health and well being of this dog since this one has a serious issue going on. Vomiting and excessive thirst can be caused by several illnesses. A dog with these symptoms needs diagnosis and probably medication. Please do not rely on forums or question and answer sites in order to care for pets.