What pea protein is and why it is in dog food
Pea protein is the concentrated protein fraction extracted from yellow field peas (Pisum sativum). Whole peas are approximately 22% protein; pea protein concentrate is 75-80% protein by weight, achieved through dry milling and air classification (which separates the dense protein particles from the lighter starch). It is rich in branched-chain amino acids (leucine, isoleucine, valine) and lysine but limiting in methionine and cysteine — the same sulfur amino acids that are precursors for taurine biosynthesis.
In dog food formulation, pea protein serves three economic purposes. First, it inflates the guaranteed analysis protein number cheaply (pea protein at $1.50-2.00/kg vs chicken meal at $2.50-3.50/kg). Second, in grain-free formulas where rice and corn have been removed, peas and other pulses become the carbohydrate base and the concentrated protein fraction backfills the protein lost from grains. Third, the powder form is functionally useful for kibble extrusion structure. The result: pea protein concentrate has been one of the fastest-growing pet food ingredients of the past decade.
The FDA-CVM 2018-2022 DCM investigation
In July 2018, the FDA Center for Veterinary Medicine issued a public alert about an apparent rise in canine dilated cardiomyopathy (DCM) cases in breeds not historically predisposed to the condition. DCM is a heart muscle disease where the chambers dilate and contractile function declines; in genetically predisposed breeds (Doberman Pinschers, Boxers, Great Danes, Cocker Spaniels) it has known hereditary causes. The 2018 alert flagged DCM in breeds outside this list — Golden Retrievers, Labradors, mixed-breeds — eating diets where peas, lentils, other pulses, or potatoes were prominent.
FDA-CVM published three formal updates: Update 1 (December 2018), Update 2 (June 2019), and Update 3 (June 2019 with named brand list). Through November 1, 2022, FDA received 1,382 reports of non-hereditary canine DCM. In December 2022 FDA announced it would suspend routine public updates pending further research, citing the complexity of establishing definitive nutritional causation. Per the AVMA News coverage of the announcement, FDA scientists concluded the relationship was likely multifactorial and that pulse ingredients (rather than the simple presence-or-absence of grains) were the focal area for ongoing investigation.
Subsequent peer-reviewed research has continued. The Adin 2019 study (Journal of Veterinary Internal Medicine) documented taurine deficiency in 24 Golden Retrievers eating non-traditional diets, with cardiac function improving on diet change. The 2022 Tufts University Petfoodology summary catalogued ongoing case series from veterinary cardiology referral centers. The 2024 Adams et al prospective 18-month study in adult dogs (PMC12408985) examined different carbohydrate sources and reported overall health and cardiac function support across the formulations tested. The science is active and the conclusion is not yet clean.
The proposed mechanism
The leading hypothesis, per the 2022 ACVIM nutritional cardiomyopathy consensus, is taurine bioavailability. Dogs are not strict carnivores and synthesize taurine endogenously from cysteine and methionine. Pulse-heavy diets are limiting in methionine and cysteine relative to muscle meat-based diets. Pulse fiber and antinutritional factors (tannins, phytates) may also bind sulfur amino acids in the gut, reducing absorption. The result is subclinical taurine deficiency in some dogs eating these formulas, leading to taurine-responsive DCM. Not all affected dogs have low blood taurine, however, suggesting at least one additional mechanism is at play.
How pea protein appears on labels
Look at the first 10 ingredients on the bag. The DCM-investigation pattern flags any combination of these in the top 8:
- peas (whole or split)
- pea protein concentrate or pea protein
- pea fiber
- pea starch
- lentils, chickpeas, faba beans
- potato, sweet potato (less central but often co-occur in grain-free formulas)
A practical heuristic: if you see two or more of these in the top 5 ingredients, the formula is what FDA-CVM was scrutinizing. The KibbleIQ rubric calls this “ingredient splitting” when peas appear in three forms (whole, protein, fiber) lower in the list because each form is below the meat ingredient by weight, but in aggregate the formula is pulse-dominated.
What KibbleIQ does with this
The KibbleIQ Dry Kibble Rubric v15 deducts when pulse-derived protein concentrates (pea protein, pea protein isolate, pea protein concentrate) appear in the top 5 ingredients, with a larger deduction when multiple pulse forms appear in the top 8. The deduction reflects the FDA-CVM 2018-2022 association data and the WSAVA 2018 / ACVIM 2022 conservative guidance, not a definitive causal finding. Whole peas as a moderate-inclusion carbohydrate (e.g., #6 or lower, single occurrence) earn a smaller penalty. Foods that meet WSAVA's manufacturer-quality criteria (full-time veterinary nutritionist on staff, AAFCO feeding-trial substantiation, documented quality-control program) and use traditional grain-inclusive formulas score highest.
For brands using or avoiding these ingredients, see our best grain-free dog food guide (curated for the lowest-pulse formulas where grain-free is needed for clinical reasons), our best food for large breeds (where DCM-prone breeds like Goldens and Labs deserve traditional formulations), and our explainer on taurine. To check your current bag, paste it into the KibbleIQ analyzer.