What's a good alternative to Royal Canin Selected Protein cat food?

The short answer

There is no single drop-in replacement for Royal Canin Selected Protein, because it isn't one food, it's a formula strategy: a novel animal protein (rabbit or duck, depending on the variant) paired with peas and hydrolyzed soy protein, sold as a veterinary-exclusive diet for cats with suspected food sensitivities. A real alternative has to match that strategy for your specific cat, not just sit in the same aisle. That means checking what protein your cat has actually eaten before, whether your vet wants a novel-protein or a hydrolyzed diet, and whether the swap is happening mid-elimination-trial or after a trigger has already been confirmed.

What Selected Protein is actually doing

According to Royal Canin's own product pages, the Selected Protein line comes in a handful of formulas built around a single animal protein the brand treats as "novel," most commonly rabbit (the PR formula) or duck (PD), combined with peas and hydrolyzed soy protein. It's sold only through veterinarians, the same "Veterinary Diet" tier as Royal Canin's other therapeutic lines, and it's most often prescribed either as part of a food-sensitivity elimination trial or as a long-term maintenance diet once a trigger protein has been identified.

Why people look for an alternative

The most common reasons aren't medical: the formula is out of stock, it's expensive relative to other therapeutic diets, or a cat simply won't eat that specific recipe. Less often, a vet has confirmed the trigger protein and is open to a wider set of maintenance options instead of staying on one brand's veterinary line indefinitely. The right next step depends on which of these is true, which is a conversation for your vet, not a label comparison.

What actually matters in a substitute

Whatever you consider next, it needs to hold up on the same three points Selected Protein is built around:

• The protein has to be genuinely novel for your cat. "Novel" only means something relative to your cat's actual diet history. Rabbit isn't novel for a cat who's already eaten rabbit-based treats or a previous rabbit formula.
• Limited ingredient claims aren't independently regulated. AAFCO doesn't define or verify "limited ingredient" as a label term, so a shorter ingredient list on the front of a bag doesn't guarantee the back panel is actually free of your cat's known trigger. Read the full panel, not the marketing claim.
• Hydrolyzed is a different tool than novel protein. If your vet specifically prescribed a hydrolyzed formula (protein broken down small enough that the immune system usually doesn't recognize it), a plain novel-protein diet isn't a like-for-like swap, even if it's also "limited ingredient."

KibbleLab's breakdown of limited-ingredient, novel-protein, single-protein, and hydrolyzed diets covers how these categories differ and when each one is actually the right tool, which is worth reading before comparing specific products.

Checking a candidate before you commit

Once your vet has confirmed what you're looking for (a specific novel protein, or a hydrolyzed formula), the fastest way to check whether a given product actually qualifies is to look at its full ingredient list against your cat's real diet history, not just its front-of-bag claims. The KibbleLab Cat Food Finder lets you filter by ingredients to avoid and see the full panel for anything you're considering, and the difference between a food sensitivity and a food allergy is worth understanding if you're not already deep into an elimination trial with your vet.

Based on Royal Canin's published product formulations and WSAVA/AAFCO nutrition guidance.

KibbleLab Explains articles are educational, and are not veterinary advice. Before starting an elimination diet, a weight plan, or any major diet change, talk to your veterinarian.