When dogs are healthy, they can go 3-5 days without nourishment. However, this is never an ideal situation. If your dog is sick and doesn’t want to eat after 2 days, make sure you call the veterinarian for advice. Make sure your dog is also drinking water. Not eating is one thing. If they aren’t drinking, they will quickly become dehydrated, which is even worse. You may have to force them to drink water if they go too long without it.