I have a 4 year old Great Pyrenees but got her almost two years ago. Last summer she was not eating well, was very weak, and would wake up whining in the middle of the night, so I took her to the vet. She has always been underweight regularly weighing about 70 lbs, but last summer she got down to 55. The vet ran every possible test they could think of and said that she had heat stroke and that we shouldn't shave her or even trim her fur. The past few days she has hardly eaten a thing and she can't even keep down what she is eating. Her energy level seems fine and she acts happy not as if she is sick or any thing.......She is interested in the food. I have been mixing canned puppy food in with her regular diet and it was working until the past few days. She still gets excited for the food and keeps my other dog from eating it, but she'll only take one bite or so only to puke it up later. Could this be from heat stroke? I have been letting her go to the creek a few times a day to keep her cool to try and help with the heat and there is always cold water for her. Is there anything I can do to help with the throwing up?