Merrick and Castor and Pollux are definitely high protein foods. If your mom is having good results with Dr. Harvey’s, you may want to try that first, rather than Honest Kitchen. (My girl does better without flaxseed so that is why I use Honest Kitchen rather than Dr. Harvey’s.) Ask your mom how much meat and oil she adds to the mix and start there. If I remember correctly, the recommended amount of meat to add is double the amount of base mix and that would be a high protein diet.
When I first started feeding base mixes, I got on BalanceIt.com and played around with the free recipes to see approximately how much protein their mid-range recipes called for my 20 lb dog, and it worked out to be around 4 oz. Honest Kitchen recommends equal amounts of dry mix and protein for normal activity level–equal amounts turned out to be about 4 oz of protein. Depending on the protein, calories will vary so I focus on calories a day my girl needs and not the weight of the protein.
One thing I should mention about Honest Kitchen complete mixes is they are ground very fine and if you mix with the recommended amount of water, it is a soupy mix. The base mixes are a chunkier mix and not soupy.
