Pick an allergen below to see which other foods commonly cross-react with it in dogs, and what the peer-reviewed veterinary literature says about each pairing. Reaction rates are case-series ranges — your vet's read on your individual dog's history is what matters for treatment decisions.
Largely species-specific. Some salmonid cross-reactivity reported.
Mechanism: Parvalbumin and other muscle proteins are conserved within Salmonidae; cross-reactivity is documented but variable.
Owner note: A dog allergic to salmon may also react to trout. Other fish families (cod, hake, tilapia) tend to be safer alternatives.
Source: Veterinary dermatology consensus
Mechanism: Whitefish species share parvalbumin but differ enough that many fish-allergic dogs tolerate one species while reacting to another.
Owner note: Often used as a "novel" alternative if the dog has only previously eaten salmon. Always confirm with vet and run the elimination trial.
Source: Limited canine-specific data
Mechanism: Shellfish (crustaceans, molluscs) are taxonomically distant from finned fish; tropomyosin is the main shared allergen but rarely the same one.
Owner note: Shellfish is uncommon in commercial dog food. Most fish-allergic dogs tolerate shellfish, but limited data — discuss with vet.
Source: Limited canine-specific data
Upload a photo of any pet food label and the free scanner flags fish and the proteins that commonly cross-react with it.
Try free scanThe cross-reactivity rates shown here are case-series figures synthesised from peer-reviewed veterinary dermatology literature. They are population averages — individual dogs can fall well outside the reported range. Vets typically use cross-reactivity data to guide which proteins to exclude during an elimination diet, not as a reason to avoid a protein the dog has tolerated for years without symptoms.
The strongest pairings (high overlap) are the ones to flag with your vet first. The lower-overlap pairings often produce the most successful "novel protein" substitutions — but always confirm the dog has not previously been exposed before starting a trial.
For the long-form context behind these decisions, see the complete elimination diet protocol and the novel-protein vs hydrolysed comparison.
Disclaimer: this tool is education for pet owners, not veterinary advice. Cross-reactivity rates vary by dog, population and methodology. Always confirm specific cross-reactivity decisions for your dog with your vet.