Yesterday I came across Sportmix Wholesomes dog food that has pretty solid ingredients with a higher kilocalorie content per cup (meaning that you can feed less of it than others foods) for a very reasonable price. Right now it looks like it's $30 for 40lbs of the fish and rice blend (if your pup struggles with chicken). Many reviewers say they've found it very useful for dogs with food sensitivities as they don't blend the proteins and keep them separate.
As for cats, I'm of the camp that any wet food is better than dry for them, so if he eats friskies or fancy feast classics or Sheba, they are all high protein and low carb and obviously high moisture, which cats need more than anything. Fancy Feast Classics and Sheba are also grain-free, at least, and many pet owners with diabetic cats are able to feed these due to the appropriate protein/carb ratio.
Anyway, good luck to you; I hope this helps.