My dog can't keep food down.

[JHSpurlock]

My dog can't keep any food down.  It has been happing off and on for the past week.  Last night he made the two biggest piles od puke I,ve ever seen.  He will eat all food I give him, but then he will go out side eat some grass then come back inside and puke.  At first I was not that worried about it but he has lost enuf wight that you can tell just by looking at him.  Please tell my what i can do to help him.

[peekawho]

Take your dog to the vet.  If he is not keeping food down and losing weight, it could be an obstruction.  

Take him to the vet immediately.  

[ea_poe]

I wound up having to switch to the Science Diet Sensitive Stomach dry food. My beagle was getting sick at least one stretch a month, same as yours, where she'd eat all of it, and then 10 minutes later throw it up. The new dog food seems to have helped, she's been on it about 2 years, and only had 1 of those stretches since.