Q. My dog wont stop panting, keeps throwing up, lethargic, and acts dehydrated.
A. This sounds very worrying.You should take him to your vets without delay as he must be dehydrated by now.Vomiting is a sign of a number of diseases (gastritis,stomach ulceration,gastrointestinal obstruction,infection,kidney failure,intoxication and many more)so it is not possible to tell you more what is going on without seeing your dog.
A. These signs are very worrying - you should see your vet without delay. Dehydration is a common complication of gastrointestinal problems and, if severe is very dangerous and detrimental for the body.