Get fresh meat and fish, and cook it with vegetables like broccoli, carrots, spinach, green beans, cabbage. Those veggies are all good for dogs. Salmon oil is also a good additive to put in their food. For carbs, (cooked) potatoes and both brown and white rice -are all okay for dogs. So is wholemeal pasta. But not too many carbs.
And you may need a food supplement tablet recommended for dogs to give daily.
No bones. Remove bones. Use lean meats, don't let them eat meat fat or fatty skin.
Some oils are essential for dogs in the correct amount daily, but not fatty foods. Try to avoid bacon and ham, though lean cooked pork is okay sometimes with veg.
Right you are,"dry foods" are not the best idea,
did your vet have any suggestions for his food?
I don't have on hands experience with this kind
of problem,perhaps going back in the forum
there might be information from others?
Since this sounds like a serious problem for
the little guy,I'm thinking your vet would have
the best answers for this and for him? I do
feel canned foods would have a lot more
moisture,easier to digest and pass through.
Wished I could help more,please come back
and let us know what you found out and how
he is doing as it may help others.
Jan