Royal Canin vs Hills Cat Food

Reviewed by Hazel, BVSc | April 2026

Walk into any veterinary clinic in Australia and you’ll find two brands on the shelves: Royal Canin and Hills Science Diet. These are the only two cat food brands that fully meet WSAVA (World Small Animal Veterinary Association) guidelines — meaning they employ board-certified veterinary nutritionists, conduct feeding trials, publish peer-reviewed research, and maintain rigorous quality control.

But “both are good” isn’t particularly helpful when you’re standing in the vet clinic trying to decide which bag to buy. This comparison breaks down the genuine differences between Royal Canin and Hills so you can make an informed choice for your cat.

Brand Overview

Both brands operate at a scale that smaller competitors simply can’t match. They employ teams of PhD-level nutritionists, run ongoing feeding trials (not just the minimum AAFCO 26-week protocol), and invest millions annually in research. This is the fundamental reason vets recommend them — not because of kickbacks (a persistent myth), but because the evidence base behind these foods is genuinely robust.

Ingredient Comparison

This is where the debate gets heated. Royal Canin’s ingredient lists frequently include poultry by-product meals, wheat, corn, and synthetic antioxidants like BHA. For owners who equate “good ingredients” with human-food aesthetics, these panels look alarming.

Hills has made a deliberate move toward cleaner-looking labels. They’ve removed artificial colours, flavours, and preservatives from their Science Diet range, and their ingredient lists tend to feature more named meat sources (e.g., “chicken” rather than “poultry by-products”). This doesn’t necessarily make Hills nutritionally superior — by-product meals are nutrient-dense and perfectly safe — but it does appeal to modern consumer expectations.

Royal Canin’s counter-argument is straightforward: they formulate to a nutrient profile, not an ingredient list. The end nutritional result matters more than whether the protein came from chicken breast or chicken liver. Both perspectives have scientific merit, and both brands produce foods that meet identical nutritional standards.

Product Range Comparison

This is where Royal Canin pulls clearly ahead. Their range includes breed-specific formulas for over 35 cat breeds — from Ragdolls to Siamese to British Shorthairs — each calibrated for the breed’s unique jaw shape, coat type, and common health predispositions. They also offer more granular life-stage targeting: Kitten, Young Adult, Adult, Mature (7+), and Senior (12+).

Hills takes a simpler approach with fewer SKUs but arguably more clinical depth per product. Their life-stage range is less granular (Kitten, Adult, Senior 7+, Senior 11+), but each formula is backed by specific published studies. Hills’ real strength is their Prescription Diet line, which includes the unique y/d formula — the only commercially available food clinically proven to manage feline hyperthyroidism through diet alone.

Prescription Diet Head-to-Head

For cats with medical conditions, the prescription diet comparison is what matters most. Here’s how the key formulas stack up:

Kidney Disease

Royal Canin Renal vs Hills k/d: Both are excellent renal diets with restricted phosphorus and high-quality protein. Hills k/d has the longer clinical track record, with published studies demonstrating significantly extended survival times in cats with chronic kidney disease. Royal Canin Renal offers more texture and flavour options, which can be critical for maintaining appetite in renal cats (who often become inappetent). Edge: Hills k/d for evidence, Royal Canin for palatability options.

Urinary Health

Royal Canin Urinary SO vs Hills c/d Multicare: Both target struvite and calcium oxalate crystals. Royal Canin SO takes a slightly more aggressive approach to struvite dissolution, creating a more acidic urinary environment. Hills c/d Multicare is formulated for ongoing maintenance and prevention, with added stress-reduction ingredients (tryptophan and hydrolysed casein) in their Stress formula. Edge: Royal Canin for acute dissolution, Hills c/d for long-term management and stress-related cases.

Digestive Care

Royal Canin Gastrointestinal vs Hills i/d: Comparable formulas for managing acute and chronic GI issues. Both feature highly digestible proteins, adjusted fibre levels, and prebiotic support. Palatability is similar. Edge: Neither — genuinely equivalent.

Allergies & Food Sensitivities

Royal Canin Anallergenic vs Hills z/d: Royal Canin Anallergenic uses hydrolysed feather protein — a more extensively broken-down protein source that’s less likely to trigger immune responses. Hills z/d uses hydrolysed chicken liver. For cats with severe or multiple food allergies, RC Anallergenic is the more restrictive (and arguably safer) choice. Edge: Royal Canin for severe allergies, Hills z/d for moderate sensitivities.

Price Comparison

In Australia, both brands occupy the same price tier. Expect to pay $35–$60 for a 2kg bag of dry food, with prescription diets at the higher end. Wet food costs are similar at $2.50–$3.50 per 85g pouch for mainstream lines, and $3.50–$5.00 for prescription options. Per-serve costs are effectively identical — neither brand offers a meaningful price advantage over the other.

Our Verdict

The honest answer? For most healthy cats, you genuinely can’t go wrong with either brand. Both are formulated by qualified veterinary nutritionists, both undergo rigorous feeding trials, and both produce consistent, reliable nutrition. The differences matter most when your cat has a specific health condition, breed-related needs, or strong palatability preferences.

Frequently Asked Questions