The scores
Eukanuba: B (76/100) — Above average. Chicken leads, but corn meal and chicken by-product meal follow closely behind.
Iams: C (58/100) — Average. Nearly the same formula as Eukanuba, with ground whole grain corn instead of corn meal and dried beet pulp instead of chicken fat.
An 18-point gap separates brands owned by the same parent company. Mars Pet Care manufactures both Eukanuba and Iams, and the ingredient lists reflect that shared supply chain. Neither brand is bad enough to earn a D, but only Eukanuba is good enough to break into B territory.
How the ingredients compare
The top five ingredients are remarkably similar:
Eukanuba: Chicken, Corn Meal, Whole Grain Sorghum, Chicken By-Product Meal, Chicken Fat
Iams: Chicken, Ground Whole Grain Corn, Ground Whole Grain Sorghum, Chicken By-Product Meal, Dried Plain Beet Pulp
Both formulas start with chicken as the first ingredient, which sounds good until you remember that whole chicken is roughly 70% water. After cooking, chicken drops significantly in the ingredient ranking by weight. That means the real workhorse ingredients — the ones making up the bulk of the kibble — are corn and sorghum in both formulas.
Position #4 is identical: chicken by-product meal in both brands. By-product meal is made from parts like organs, necks, and feet — not inherently harmful, but a lower-quality protein source than whole chicken or chicken meal made from muscle meat. It’s a cost-saving measure, and both Mars brands use it in the same position.
The only meaningful difference in the top five is position #5. Eukanuba uses chicken fat, which is a named animal fat that provides essential fatty acids and is generally well-regarded. Iams uses dried beet pulp, a fiber source that aids digestion but doesn’t add protein or meaningful nutrition.
Where Eukanuba pulls ahead
Named fat source: Chicken fat at position #5 is Eukanuba’s most notable advantage. A named animal fat is always preferable to generic “animal fat” because you know exactly what species it comes from. Chicken fat is rich in omega-6 fatty acids (linoleic acid) that support skin health and coat quality. Iams doesn’t include a named fat source in its top five, relying instead on dried beet pulp as a filler-adjacent fiber source.
Brand positioning and research: Eukanuba has historically positioned itself as a performance-oriented brand with a focus on breed-specific nutrition and an active dog lifestyle. The brand invests in feeding trials and has formulas tailored to different breed sizes. While the base ingredients don’t fully live up to the premium marketing, Eukanuba’s feeding trial history and size-specific formulations are a minor plus for owners who want that specificity. Shop on Amazon →
Where Iams holds its own
Iams’ biggest advantage is price. It’s consistently cheaper than Eukanuba, often by a meaningful margin per pound, while delivering an almost identical formula.
Iams also has enormous distribution. It’s available at virtually every grocery store, big-box retailer, and pet store in the country. For owners in rural areas or those who prefer to grab dog food during their regular grocery run, Iams’ ubiquity is a practical convenience that shouldn’t be underestimated.
The dried beet pulp at #5 in Iams isn’t exciting, but it’s a well-known prebiotic fiber source that supports healthy stool quality. Many dogs do well on beet pulp, and it’s a functional ingredient even if it doesn’t contribute the nutritional value of chicken fat.
Ultimately, Iams is a mass-market food at a mass-market price. Shop on Amazon →
The bottom line
Eukanuba beats Iams by 18 points, B/76 to C/58. The two brands come from the same parent company with nearly identical ingredient lists.
If you’re currently feeding either brand, it’s worth knowing that genuinely better options exist at similar price points. Diamond Naturals scores a B (78/100) with named chicken, chicken meal, brown rice, and barley — a meaningfully cleaner formula for roughly the same cost as Eukanuba. That’s a 2-to-20-point improvement without spending more money.
Read our full reviews of Eukanuba and Iams for the complete breakdown of each formula.
Corrected 2026-10-19: we removed claims we could not support; we corrected factual errors, and grades and score comparisons that did not match our current scores.