Whey

162 foods contain this ingredient

Protein Dairy allergen group

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About Whey

Whey is the liquid byproduct left over from cheese making, containing milk proteins along with lactose and minerals, dried into a powder and added to pet food for its amino acid content and taste.

Whey is a dairy-derived protein and flavoring commonly used in pet foods and treats as a highly digestible, high-quality protein source rich in essential amino acids (including branched-chain amino acids) and some minerals and B vitamins. It can support muscle maintenance and improve palatability for dogs and cats, but may cause gastrointestinal upset in lactose-intolerant animals and should be avoided in pets with milk allergies or used cautiously to prevent excess calories or mineral imbalance.

Related ingredients

Milk Cultured Whey Sweet Whey Whey Product Whey Protein Whey Protein Concentrate Whey Soluble

Derived from: milk (cheese production byproduct)
Primary role: protein and palatant

Why it's used

Manufacturers add whey because its amino acid profile, particularly its leucine content, is associated with lean muscle support, and it is frequently used in formulas for weaning puppies and kittens or for pregnant and lactating mothers. It also acts as a flavor enhancer that can increase a food's palatability.

Common concerns

Dairy allergen status Merck Veterinary Manual and veterinary allergy references list dairy among the most common food allergens identified in dogs and cats, alongside beef, chicken, and fish.
Lactose sensitivity VCA Animal Hospitals notes that lactose intolerance, most often discussed in cats, can produce diarrhea, vomiting, bloating, or abdominal discomfort after ingesting milk-derived ingredients.
Distinguishing intolerance from allergy Whey itself can be an allergenic milk protein separate from lactose, so a lactose-free claim does not necessarily mean an animal with a dairy protein allergy will tolerate it; a veterinary elimination trial is the standard way to confirm a diagnosis.

Also relevant

Because whey is a dairy derivative, it falls under the broader dairy allergen group along with other milk-based ingredients like casein, milk protein, and lactose.

4 sources cited