Tiki PetsVariety Mega Jar

A fatty fish used as a protein source and as a natural source of omega-3 fats. Fresh salmon is mostly water, so a salmon meal lower on the list may be contributing more protein. Salmon is a common alternative protein for pets that react to chicken or beef, though fish allergies exist too. Farmed and wild salmon differ in fat profile, and labels rarely say which.

A complete, highly digestible protein, which is why formulators like it. It is also a documented allergen in about 4% of dogs with food reactions. Egg allergy does not implicate chicken meat; the proteins are different. Dried egg product is the same thing with the water removed. A good ingredient for most pets and a fine-print one for the allergic few.

A fish used mostly in cat foods, where its strong flavor is the point. Tuna is a good protein and a source of omega-3 fats. Two cautions apply to tuna fed often: it is higher in mercury than smaller fish, and cats can become fixated on it and refuse other foods. Both cautions apply to the cat eating tuna every day, and much less to tuna as one ingredient in a complete food fed in rotation.

The most common protein in pet food, and for dogs one of the most common food allergens, with beef and dairy. If chicken is what your pet reacts to, it hides everywhere: chicken fat, chicken broth, chicken meal, natural flavor. On a label, chicken listed first is weighed with its water still in, so a food leading with fresh chicken often has less chicken protein than one leading with chicken meal. Neither is better; they are different measures.