My Dog Keeps Throwing Up Everything He Takes In. What Causes This?

There are many things that cause vomiting in dogs.  Some causes include viral infection (parvovirus for example), dietary indiscretion, pancreatitis, foreign body obstruction, liver disease, and kidney disease.  Your dog needs veterinary care--3 days is a long time for recurrent vomiting.  By this time your dog is likely dehydrated and needs fluid therapy.  Have your dog examined by a veterinarian so appropriate diagnostics (likely bloodwork and x-rays) can be run and treatment/supportive care can be started.
Oral medications do not work in dogs that are vomiting--they vomit medications and do not get absorbed.
Certain causes of prolonged vomiting are serious please seek treatment for your dog.

If your dog 'Regurgitates' its entire food, STOP feeding it 'PURINA' dog food. Our Chihuahua mix never liked it. We add water & some chicken but after a year he went from regurgitating once a month to every meal. We went to Vet, no parasites. Buy Kirkland and mix rice & chicken he's 100% ok

Give a small dose of pepto bismol, and see if that will help the vomiting, if not, then you need to get her to the vet as soon as you can, because they aren't really capable of going without food and water really for 3 days. Hope this helps, good luck to you.

I would feed the dog a very mild diet (see his vet) and hand feed in very small quantities. Many times a day. Too much will make him throw up. My dog does this - mild food in small but often quantities is the trick

My dog does this. I found a dog food that is very mild and then hand feed him small quantities several times a day - he may 'bolt' the food down fast and can't handle the volume - he may not be able to tolerate very rich foods.

It can happen because of a number of reasons like he might have eaten something disagreeable, eaten too much, too fast or exercised too soon after eating, are overly excited or nervous etc You should take away all it's food and water to do the treatment at home and if the situation aggravates (like blood in vomit) then you should go to the vet.

Its provo you mint what to take it to your vent for a provo test