The scores
Kirkland Signature Adult Chicken & Rice: B (78/100) — Above average. Dual chicken proteins lead, backed by quality whole grains, probiotics, and joint-support supplements.
4Health Grain-Free Chicken Formula: C (70/100) — Decent. Chicken first is a good start, but the grain-free formula leans on pea protein and skips the extras that matter.
How the ingredients compare
Both brands lead with chicken — a strong start for store-brand formulas. The difference shows up immediately after that first ingredient.
Kirkland Signature: Chicken, Chicken Meal, Brown Rice, Barley, Oatmeal
4Health: Chicken, Sweet Potatoes, Peas, Pea Protein, Chicken Fat
Kirkland doubles down on animal protein with chicken meal in position two — a concentrated protein source that’s roughly 3x the protein density of whole chicken. Then it fills positions three through five with whole grains that provide fiber, B vitamins, and sustained energy. 4Health fills those same slots with sweet potatoes, peas, and pea protein — that last one is a plant-based protein concentrate often used to inflate the protein percentage on the guaranteed analysis without adding nutritional depth.
But the real gap is in the supporting cast. Kirkland includes probiotics for digestive health, glucosamine and chondroitin for joint support, and flaxseed for omega-3 fatty acids. 4Health includes none of those. No probiotics, no joint supplements, no omega-rich seeds. That’s where the 8-point gap comes from.
Where Kirkland Signature pulls ahead
Supplement depth: Kirkland’s formula reads like a food costing twice its price. Probiotics support gut health and nutrient absorption. Glucosamine and chondroitin provide joint support that’s especially valuable for larger breeds. Flaxseed delivers plant-based omega-3s for skin and coat. 4Health offers none of these — its supplement stack is bare-bones for a formula at any price.
Grain quality over grain-free marketing: Brown rice and barley are nutrient-dense, slow-digesting carbohydrates with a long track record in canine nutrition. 4Health’s grain-free positioning sounds premium, but the FDA’s ongoing investigation into a potential link between grain-free diets and dilated cardiomyopathy (DCM) in dogs means that avoiding grains may actually add risk without any ingredient quality benefit.
Protein strategy: Chicken plus chicken meal gives Kirkland two named animal protein sources in the top two positions. 4Health has chicken first but relies on pea protein — a plant-based filler — to round out its protein numbers. That’s a meaningful quality difference in how the protein on the label actually gets there. Shop on Amazon →
Where 4Health holds its own
4Health’s no corn, no wheat, no soy formulation is genuinely clean on that front. Dogs with sensitivities to those specific grains will find 4Health easier to digest. Sweet potatoes are a quality carbohydrate source with natural beta-carotene, and chicken first is always a solid foundation.
Availability is the other factor. 4Health is a Tractor Supply exclusive, and if that’s already where you shop, it’s a convenient grab. Kirkland requires a Costco membership, which adds a $65/year cost that budget-conscious buyers need to factor in.
For dog owners specifically avoiding all grains on veterinary advice, 4Health is the only option between these two. Just make sure that recommendation comes from your vet, not from marketing. Shop on Amazon →
The bottom line
Kirkland Signature is the better food here, and it’s not particularly close. An 8-point lead that spans a full letter grade — C to B — reflects real differences in formula depth: probiotics, joint supplements, quality whole grains, and dual animal protein sources that 4Health doesn’t offer. Both brands target the same budget-conscious buyer, but Costco’s house brand delivers genuinely premium ingredients at a store-brand price.
If you have Costco access, Kirkland Signature is the clear winner for your dog and your wallet. Read our full reviews of 4Health and Kirkland Signature for the complete breakdown.