I just used WDJ’s new searchable dry dog food database to look for potential new foods to feed my 14-year-old dog, Otto. One goal when feeding most senior dogs is to find a food with a moderate amount of high-quality protein. I used the “minimum protein content” column to help me zero in on the foods that contain the amount of protein I want to feed Otto, and then looked at the ingredients of each of the candidate foods. All of that information, organized for you (and me!) in one handy place!
But allow me to explain those italicized terms a bit.
Protein levels in Dog Food: Low, high, moderate
The minimum requirement for crude protein in an adult dog maintenance diet is 18% on a dry matter basis, which (assuming an average moisture content of 10%) is 16.2% “as fed” (as it is in the package). The minimum requirement for crude protein for dogs in a “growth/reproduction” phase (or “all life stages,” which includes puppies and moms) is 22.5% dry matter, which is 20.25% “as fed” (assuming 10% moisture).
The Association of American Feed Control Officials (AAFCO) does not state a maximum level for protein.
We’d define “moderate” as something near the midpoint between the legal minimum and the highest amount of protein you can find in any dry dog food on the market.
Using the WDJ searchable database of approved dry dog foods, you can click on the top of the “minimum % protein content” column to make all the 1,100-plus foods appear in order by protein content. When ordered so that the foods with the lowest amount of protein appear at the top, you’ll see just a few products with just 17% and 18% protein – and these are mostly “weight control” foods. (However, a few of them are labeled as being appropriate for senior dogs, which, in our opinion, is sad. Senior dogs definitely need more protein than the minimum allowed.)
By clicking on the top of that column again, so that the foods with the highest amount of protein appear at the top, we can find products with very high amounts of protein in them, with numbers in the low 40s (43%, 42%, 41%).
The exact midpoint, in this case, is 30%. We think this is a good, moderate amount of protein for most senior dogs.
Note that there are more opinions about protein levels in dog food than there are veterinary nutritionists. This shouldn’t be a surprise; there is little consensus among experts in human nutrition about ideal protein levels, too.
Older veterinarians tend to regard foods with even moderate protein levels as potentially dangerous, or, at a minimum, a waste of money. When you feed a lower-protein diet to a dog, you decrease the amount of nitrogenous waste delivered to the kidneys for excretion in the urine; it was speculated that one could preserve the dwindling kidney function of dogs with chronic kidney disease by giving their kidneys less work to do (by feeding a lower-protein food to the dog).
However, according to veterinary nutritionists Andrea Fascetti and Sean Delaney, “the effect of protein restriction on the progression of renal damage in dogs and cats remains controversial and no definitive study exists on this matter.” (Quoted from “Nutritional Management of Chronic Renal Disease” on the website for the UC Davis School of Veterinary Medicine.)
While it’s been demonstrated that some dogs with chronic kidney disease improve when their dietary protein is moderately restricted, this has frequently (and tragically, in our opinion) been extended to all older dogs, whether or not they have any kidney problems at all. Today, it’s well-accepted that most older dogs actually benefit from diets that contain more protein – as long as it’s a high-quality protein – than young adult dogs.
However, there is newer evidence, based on newer criteria, very high protein dog food diets is potentially harmful for dogs to eat. (See this post by Linda Case, MS, Canine/Feline Nutrition, for details.) This give us even more confidence in our advice to look for foods with moderate protein levels.
What constitutes a high-quality protein?
Broadly speaking, the quality of a protein depends on its digestibility and its amino acid profile – that is, whether it contains adequate amounts of the amino acids that dogs require. In general, animal-sourced proteins contain more of the amino acids that are essential to dogs (and they are supplied in proper ratios for benefitting dogs) than do plant-sourced proteins.
The digestibility of ingredients depends on a number of factors, too numerous to explain here. (If you’re especially curious, read Linda Case’s 2017 piece for WDJ about digestibility here.) The bottom line: Pet food companies typically conduct digestibility studies on their finished products; they should know how digestible their products are, and they should be able to furnish consumers with that information. We should all be asking for this information!
A final thing to keep in mind
The amount of protein listed on a dog food label is the guaranteed minimum present in the food. It may contain much more! To be certain, ask the company for the amount of protein in their products – a number from an actual nutrient analysis.