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Quick answer: Both are long-established, science-led brands, and both make complete and balanced foods. Choose Royal Canin if you want food tailored to a specific breed or size, or have a fussy eater. Choose Hill’s Science Diet if you want a straightforward range organised by life stage and common needs such as weight or a sensitive stomach. For a dog with a medical condition, the choice is your vet’s, between the two brands’ prescription ranges.
How we put this guide together: We have not run a feeding trial, and we are not vets. We compared what each company publishes about itself with independent reference sources: the Association of American Feed Control Officials (AAFCO) on ingredients, and the World Small Animal Veterinary Association’s guidance on choosing a pet food. We don’t quote prices, because they vary a lot by formula, bag size and retailer.
Hill’s Science Diet vs Royal Canin at a glance
| Hill’s Science Diet | Royal Canin | |
|---|---|---|
| Origins | Grew out of veterinarian Mark Morris Sr.’s work on therapeutic diets; Science Diet developed in the 1960s | Founded in France in 1968 by veterinarian Jean Cathary |
| Owner | Colgate-Palmolive (since 1976) | Mars, Inc. (since 2002) |
| How the range is organised | Mainly by life stage and need (puppy, adult, senior; weight, sensitive stomach and skin, small paws, large breed) | Mainly by breed and size, plus life stage and specific needs |
| Veterinary (prescription) range | Hill’s Prescription Diet | Royal Canin Veterinary Diet |
| Typical price | Both are premium brands; Royal Canin is usually the more expensive of the two. Compare current prices for the exact formula and bag size you need. | |
Two vet-founded brands
Both brands trace back to veterinarians who believed food could support health. Hill’s origins lie with Mark Morris Sr., who, according to its history, created a special diet for Buddy, a guide dog with kidney disease. That work led to its therapeutic foods, and the everyday Science Diet range followed in the 1960s. Hill’s has been part of Colgate-Palmolive since 1976.
Royal Canin says it began in 1968, when French veterinarian Jean Cathary developed a food for dogs. In its own words, it has worked “to make nutrition cats and dogs first medicine”. It has been part of Mars, Inc. since 2002, and is best known for breed-specific and size-specific formulas.
Breed-specific or life-stage? The real difference
The biggest practical difference is how each range is built.
- Royal Canin makes formulas for individual breeds, such as Labrador, German Shepherd and French Bulldog, and for size bands from mini to giant. Kibble size, shape and texture vary by formula, which can suit breeds with particular jaw shapes or eating habits.
- Hill’s Science Diet keeps its range simpler, grouped by life stage and common concerns. If your dog is a mixed breed, or you simply want a reliable adult food, this structure is easy to navigate.
A breed-specific food isn’t a must. Plenty of dogs do well on a general complete and balanced food suited to their size and life stage. Some owners find breed formulas a convenient way to match kibble size and calorie density to their dog.
What about by-products?
Ingredient lists that include “by-products” worry some owners, and premium brands, Royal Canin among them, are often criticised for using them. AAFCO defines by-products as “secondary products produced in addition to the principal product”, such as organs left over from human food processing. Its position is that “byproducts can be safely used to provide nutrition”, and that being a by-product doesn’t make an ingredient unsafe or low in nutrition. Read ingredient lists if you have a preference, but the order of ingredients alone tells you little about a food’s overall nutritional quality.
How to judge any dog food brand
The World Small Animal Veterinary Association (WSAVA) suggests asking manufacturers a few questions that matter more than marketing claims. These are reproduced on many sites, including Royal Canin’s own:
- Do you employ a full-time, qualified nutritionist, and what are their qualifications?
- Who formulates your diets?
- Are your foods tested with AAFCO feeding trials, or formulated to meet AAFCO nutrient profiles?
- What research have you done, and is it published in peer-reviewed journals?
Hill’s and Royal Canin both have the in-house nutrition science that these questions look for, which is one reason vets often stock them. Whichever you choose, check that the bag says the food is complete and balanced for your dog’s life stage.
Which should you choose?
Our verdict: Pick Royal Canin if your dog is a breed it makes a dedicated formula for, if you have a very small or very large dog, or if your dog is a fussy eater and you want to try a texture designed for its size. Pick Hill’s Science Diet if you want a simpler life-stage range, have a mixed-breed dog, or want to spend somewhat less on a premium food.
Ask your vet first if your dog has a diagnosed condition such as kidney disease, food allergies, urinary stones or a digestive disorder. Both companies make prescription diets for these, and the right one depends on the diagnosis.
Whichever brand you choose, switch gradually over several days by mixing in more of the new food each day, and check that your dog keeps a healthy weight.
Frequently asked questions
Is Royal Canin better than Hill’s Science Diet?
Neither is better for every dog. Royal Canin specialises in breed- and size-specific formulas; Hill’s Science Diet focuses on life stage and common needs. Both are complete and balanced foods from vet-founded companies with in-house nutrition science.
Why is Royal Canin more expensive?
Royal Canin is usually priced above Hill’s Science Diet, partly because of its large range of breed-specific and size-specific formulas. Prices vary widely by formula, bag size and retailer, so compare the exact products you’re considering.
Are by-products in dog food bad?
Not necessarily. AAFCO defines by-products as secondary products, such as organs left after human food processing, and says they can be safely used to provide nutrition. Whether a food is complete and balanced matters more than any single ingredient.
Do I need a vet’s approval for these foods?
Not for the everyday ranges (Hill’s Science Diet and Royal Canin’s breed and size foods). The prescription ranges, Hill’s Prescription Diet and Royal Canin Veterinary Diet, are meant to be used under a vet’s direction for specific medical conditions.
Further reading
- Blue Buffalo vs Hill’s Science Diet
- Dog Food for Sensitive Stomachs: How to Choose
- Grain-Free vs Grain-Inclusive Dog Food
Sources
- AAFCO, “Byproducts” (Understanding Pet Food). aafco.org
- Royal Canin, “Our history”. royalcanin.com
- Royal Canin, “Pet food safety questions to ask your manufacturer” (reproducing WSAVA’s guidance). royalcanin.com
- “Hill’s Pet Nutrition”, Wikipedia (company history and ownership). wikipedia.org
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