What to possibly use and how to feed puppies ONLY after discussion with your veterinarian:

Debbie”s puppy feeding (after dozens she has had):
Mothers Milk replacement (not Walmart brand)
Baby rice or baby oatmeal cereal
Canned pureed baby food

Other suggestions:
Used by someone very experienced with ME puppies and getting them to resolve their ME:
“With puppies, I have fed watered down, mashed dry kibble. I add to that a number of things for extra calories, such as canned pure pumpkin, baby cereal flakes, coconut oil, pureed baby food, etc. to make it a milkshake consistency. They really do get all the water they need from this, but you can also add Thick-It to water to give them. Walgreen’s has their own brand, which is cheaper and works just as well. Upright time after feeding is a necessity. I have used a baby walker, a front-pack carrier or simple holding them up over your shoulder while you walk around doing chores. Nothing by mouth” pertains to crumbs left on the floor or free standing water. Those tend to be the culprits for these puppies.”

Here are some questions and answers from an ME  owner and answered by another experienced ME owner. This is an example and must be discussed with your veterinarian:
1.  How many times a day to feed her?
“At that age, I’d feed every 3 hours”

2.  Amount per feed??? Less or normal?
“This varies a lot, start with lower amounts and work up, sometimes it takes work to get them to tolerate much.”

3.  Wet food ? Harder ? My vet said kibble?
“No kibble! Kibble stretches the esophagus out especially in puppies. I find for the 2 ME babies I’m raising here what works best is either firm canned food, or blending canned food with water and gelatin and then letting it set up until firm in the fridge, and giving in small meat balls. But every puppy is different. ME
puppies I’ve had in the past some did best on REALLY liquidy food, some did best on thick pudding like consistency, some did best with straight canned or meat balls, it’s kind of trial and error. You want it as smooth as possible so it slides right now, but other then they it’s kind of an experiment to see what works for that
individual puppy.

I would still use formula at 4.5 weeks with the canned food. The prescription diets that are highly digestible work really well for the ME dog. You want a formula that will digest easily and leave the stomach. We had a litter of parvo pups who weren’t even weaned (not me but needing special care) and the prescription diet and formula helped get them on the road to recovery. The diets aren’t cheap, but worth it if they work. We have had our PRAA pup on the High Energy GI diet canned food from Royal Canin and I think it works well with the calories needed and doesn’t sit in the stomach risking regurg, plus it is easy to make into a slurry.

When you add ANYTHING to dog food, you are altering the nutritional composition. A young puppy needs specifically what is in dog food, proper amounts of protein, calcium, etc. When you add anything you are increasing some, decreasing others, some may not change But it is no longer a balanced diet.”

More suggestions:
Used by another very long time ME owner who has owned and fostered dozens of ME dogs over 14 years:
“The main thing is to find a food that he can eat, not regurg and thrives on.  Each case is different, and I have more than 14 years’ experience dealing with ME in pups.  Usually, the key is to NOT let them drink any water by mouth.  They will get all they need from their food.  You can give them an ice cube while sitting upright if you think they need it.

I usually take dry kibble, cover it with water and let it soak a minimum of 30 minutes, then add more water and soak until the kibble is “spongy”.  Then I use a bartender’s hand blender to blend it smooth.  Here is where you can make it as thin or thick as you need.  If your pup does well with meatball consistency, great.  If he needs it a little thinner, you can just add a little water to it and let him lap it out of a bowl.

It is imperative that he bed fed upright.  You can achieve this in a number of way since he’s still so little.  Take a laundry basket, garbage can or some such container and prop pillows or towels around him to keep him snug, but comfortable.  After feeding, keep him upright a minimum of 15-20 minutes and see how he does.  Some dogs need longer sit-times, so it’s trial and error at this point.

The good news is that your pup is still young, and with proper management, has a greater chance to outgrow MegaE – yes, it does happen!!  I have two GSDs that will be 12 years old on the 23rd, both born with ME (brother and sister) and they both went into remission by 9 months old.  Even though they have gone into remission, or outgrown it, they will usually always be considered to be ME dogs by the vet community.  My male is over 100 pounds and my female is 86 lbs.”