Megaesophagus literally means "big esophagus," and it occurs when this vital tube becomes weak for some reason, enlarges, and loses some or all of its ability to carry food from the mouth to the stomach. Any dog can develop megaesophagus, but it's more common in larger breeds. There are no "one size fits all" solutions to feeding a dog with this issue. Your veterinarian can help you put together a feeding plan to fit your dog's specific needs.
Some dogs inherit a tendency to megaesophagus, while in others it's a consequence of myasthenia gravis, a muscle weakness of the face and neck. Some puppies are born with vascular ring anomaly, a condition in which tissue rings limit the esophagus' ability to expand. In this case, your vet can perform surgery to cut the rings. Some dogs may swallow a foreign object that scars the esophagus, causing development of megaesophagus. In most canine cases, however, no cause is evident. Your vet diagnoses megaesophagus based on symptoms and X-rays. While there's no cure if no cause is found, careful management can help your buddy continue to enjoy a good quality of life.
Dogs suffering from megaesophagus regurgitate their food. You might confuse this with vomiting, but it's not the same. When dogs vomit, food comes up from the stomach, along with stomach juices. You'll see the dog's stomach contracting as he actively "throws up." With regurgitation, the food never gets to the stomach, and it comes back looking pretty much the same as it did in the food bowl, albeit somewhat chewed. One of the great dangers of megaesophagus is food inhalation, followed by aspiration pneumonia, which is life-threatening. If your dog starts coughing constantly, runs a fever or has difficulty breathing, get him to the vet immediately.
Work with your vet to determine the best way to feed your dog. After some trial and error, you will learn what works best for him. A liquid diet works for some dogs, canned or dry for others, or perhaps some combination of all three. In some cases, it may be best to feed a high-protein canned food that you have pureed or formed into little meatballs. Feed many small meals throughout the day, rather than a couple of large meals. In some cases, a vet will insert a feeding tube directly into the stomach to bypass the mouth and esophagus entirely.
If he doesn't have a stomach tube, your pal will need to eat and drink from bowls that are elevated so that he has to stretch up to reach them. The Merck Veterinary Manual says dogs with megaesophagus should be fed from "an elevated position with the forelimbs higher than the hindlimbs." In some cases, a small stepladder works, with the bowl secured on the top platform of the ladder, and the dog placing his front feet up on an appropriate step to eat or drink from the bowl. This forms a slope from the dog's mouth to the stomach, allowing gravity to aid the downward passage of food or water. The Merck Veterinary Manual says it's best to have the dog hold that position for at least 10 to 15 minutes after eating, to let gravity "assist food passage into the stomach" and prevent regurgitation.