Two products can both list 28% crude protein and differ by 20 percentage points in what your dog actually absorbs. Here is how digestibility is measured, why amino acid profile matters as much as quantity, and what the Maillard reaction does to protein quality during processing.
Digestibility: The Number the Label Doesn’t Show
A dog food bag shows crude protein percentage. It does not show digestibility — the proportion of that protein your dog’s gut actually absorbs and uses. This distinction matters because digestibility varies substantially between protein sources and between products, even when the guaranteed analysis shows the same headline number. Two products both listing 28% crude protein can differ by 15–20 percentage points in the amount of usable protein that reaches the bloodstream and supports muscle, organ, coat, and immune function. The crude protein number is a chemical measurement of nitrogen content. Digestibility is a physiological measurement of what your dog’s body can do with it.
How Protein Digestibility Is Measured
True digestibility is determined through controlled feeding trials. A dog is fed a measured quantity of a specific protein source, and the nitrogen content of the food is compared to the nitrogen content of the faeces over a defined collection period. The difference represents what was absorbed. Values are expressed as a digestibility coefficient — for example, 0.87 means 87% of the crude protein was absorbed. High-quality animal protein sources typically achieve coefficients of 0.82–0.92. Lower-quality or heavily processed protein sources can fall below 0.70. Digestibility coefficients are not required on pet food labels anywhere in the world.
Why Amino Acid Profile Matters as Much as Quantity
Protein is not a single compound. It is a collective term for molecules assembled from 22 amino acids, of which 10 are essential for dogs. The essential amino acids include arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Each performs specific physiological functions. Taurine supports cardiac muscle function. Methionine is required for cellular methylation and coat keratin structure. Lysine is critical for collagen synthesis and immune function.
A protein source with a high crude protein percentage but a limited amino acid profile will not meet the dog’s full nutritional requirements regardless of the headline number. The amino acid profile of a protein source is determined by which animal or plant it comes from, and how it was processed.
The Role of Processing in Protein Quality
Protein quality in a finished pet food is not fixed at the ingredient sourcing stage. It is also shaped by what happens to those proteins during manufacturing. Two processing-related mechanisms reduce amino acid availability: the Maillard reaction (free lysine bonds with reducing sugars at high temperatures, forming compounds that register as protein nitrogen in a crude protein test but cannot be absorbed as functional lysine — reactive lysine losses of 5–30% have been documented in commercial dry pet food) and excessive heat and pressure (which can cross-link protein structures into configurations that resist enzymatic digestion).
Both mechanisms are processing-dependent. The Canine Plus+ RawFusion process is designed to preserve amino acid integrity through controlled processing conditions, reducing both Maillard-related lysine loss and non-enzymatic cross-linking.
What High-Quality Protein Looks Like in Practice
High protein digestibility in finished dog food is associated with several identifiable characteristics: lean, firm stools (well-digested protein produces small, firm, low-odour stools); coat condition (methionine and cysteine are the primary amino acids in keratin — adequate supply correlates with coat shine and reduced shedding); muscle tone (branched-chain amino acids are the primary substrate for muscle protein synthesis); and energy and alertness (amino acids are precursors to neurotransmitters including serotonin and dopamine).
How to Evaluate the Protein in Your Dog’s Current Food
A practical checklist: check the ingredient list, not just the crude protein percentage; look for a voluntary digestibility disclosure; look at whether omega-3 is voluntarily disclosed; observe your dog over 6–8 weeks (stool size and consistency, coat condition, and energy levels are all proxies for protein digestibility); ask about transition support (a manufacturer confident in their protein quality will typically provide a structured transition protocol).
Frequently Asked Questions
What is the difference between crude protein and digestible protein? Crude protein is a laboratory measurement of total nitrogen content, converted to a protein equivalent. Digestible protein is the proportion of that nitrogen that is absorbed through the gut wall and made available for physiological use. The two numbers can differ substantially depending on the source and how it was processed.
How do I know if my dog is digesting protein well? Stool consistency and volume are the most accessible indicators. Well-digested protein produces small, firm, low-odour stools. Large, loose, or highly odorous stools can indicate poor digestibility.
Does my dog need more protein as they age? Current research supports maintaining or modestly increasing high-quality protein in senior dogs. Age-related muscle loss (sarcopenia) is partly driven by reduced protein synthesis efficiency — meaning the protein digestibility becomes more important, not less, as dogs age. Canine Plus+ Vitality is formulated with this in mind.
Can a dog eat too much protein? In healthy adult and senior dogs without pre-existing kidney disease, dietary protein at levels found in quality dry dog food does not cause or accelerate kidney damage. The concern about high protein and kidney function applies primarily to dogs already diagnosed with reduced kidney function.