Animal Digest in dog and cat food

Is it OK for dogs and cats?

Dogs

The sources reviewed here identify no health risk from animal digest at the small amounts used to flavor complete dog foods. FDA tested dry dog foods bought in 1998 and 2000. It found no dog or cat DNA and judged the low levels of the euthanasia drug pentobarbital it found highly unlikely to harm dogs. FDA notes that these surveys cannot predict what is in foods sold today.

Cats

The sources reviewed here identify no health risk from animal digest at the small amounts used to flavor complete cat foods. Palatants such as digests are used in cat foods as well as dog foods, though those made for cats generally differ from those made for dogs. FDA's residue testing covered dry dog food only, so these sources contain no comparable data for cat food.

How settled this is: A popular concern the sources do not support

What animal digest is

Animal digest is made by hydrolysis: clean, undecomposed animal tissue is broken down with chemicals and/or enzymes. Hair, horns, teeth, hooves and feathers are excluded, apart from unavoidable traces. Poultry digests use parts such as livers, hearts, heads, feet and viscera. Beef and pork digests use clean, non-rendered parts such as lungs, spleen, kidneys and livers. The enzymes are usually proteases and lipases, which break down proteins and fats. The product comes as a liquid or a dry powder. If the name states a kind or flavor, such as 'chicken digest', the material must match that name. This description follows a 2021 review's summary of the US (AAFCO) definition. The EU Catalogue of feed materials has no entry called 'animal digest'. Its closest entry is 'hydrolysed animal proteins': polypeptides, peptides and amino acids made by hydrolysing animal by-products. When the Catalogue is used for labelling, the name is supplemented with the animal species (such as avian or porcine) where appropriate.

Why it is in pet food

Dry kibble is the most popular but least palatable form of pet food, so flavor enhancers (palatants) are added to make it more acceptable to pets. A 2021 review describes animal digest as probably the most commonly used of these. Breaking down the tissue releases amino acids and fatty acids. These react with sugars (the Maillard reaction) to give aromas that a trained human panel described as meaty and brothy. Palatants are mostly sprayed onto the surface of dry food. Dry powders are usually added at about 0.5–2% and liquids at about 1–3%. A named digest, such as chicken digest, is one kind of listed ingredient that can supply the flavor in a product called, for example, 'chicken flavored'. Under AAFCO's flavor rule, a listed ingredient must provide the named flavor, but the food does not need a large amount of an ingredient that only provides flavor.

What it does in the food

Animal digest is used for flavor rather than as a main source of nutrients, and only small amounts are added. Because it is hydrolyzed animal tissue, it contains protein fragments (peptides and amino acids) and fatty acids from the breakdown of fat. A 2025 study tested a related ingredient, hydrolyzed chicken liver, as the only animal protein in dry cat diets, at far higher levels than a flavor coating. The 20 adult cats in its palatability test mostly preferred these diets over diets based on poultry by-product meal. The authors described the hydrolyzed liver protein as well digested, although fat or energy digestibility was lower on some of the hydrolysate diets. They called for research on long-term effects. Three of the authors worked for the company that supplied the ingredient and funded the study.

Safety and limits

The cited sources set no specific limit for animal digest. FDA has investigated residues of pentobarbital, a drug used to euthanize animals, in rendered or hydrolyzed animal ingredients. It tested dry dog foods bought in 1998 and 2000 and found low levels in some samples. It saw associations between pentobarbital and rendered or hydrolyzed ingredients. In the first survey, the link was strongest for animal fat and somewhat weaker for animal digest. FDA stresses that the sampling was not representative and was a snapshot in time. It says no conclusions about dog food in general can be drawn, and the results do not predict what is in foods on the market today. FDA also tested for dog and cat DNA and found no material from dogs or cats. At the time, FDA assumed the residues came from euthanized cattle or horses that had been rendered. Its 2002 risk assessment concluded it was highly unlikely that a dog eating dry dog food would have adverse effects at the levels found. These surveys covered dry dog food only. The cited sources contain no comparable testing of cat food.

What depends on the amount and the recipe

The source: 'animal digest' does not name the species. A named digest, such as 'chicken digest', must match its name. If your pet must avoid a particular animal protein, an unnamed digest leaves the source unclear, so ask the maker. The amount: palatants are a small part of a dry food, usually about 0.5–3%. The species and food form: flavor enhancers used in cat foods generally do not serve the same purpose in dog foods. Those made for canned or semi-moist food may not work on dry food.

Not the same as

• Natural flavor — A broad label term for flavorings that can come from plants, yeast or animals. 'Animal digest' names one specific ingredient made from animal tissue.
• Chicken by-product meal — A rendered, dried protein meal used as a main protein source, not a hydrolyzed flavor coating.
• Meat by-products — Non-rendered clean parts of slaughtered mammals other than meat, such as organs. They are not hydrolyzed into a flavor concentrate.
• Animal fat — Rendered fat that supplies energy and flavor. It is not a hydrolyzed protein material.

Sources

1. Dry Pet Food Flavor Enhancers and Their Impact on Palatability: A Review (Samant et al., Foods 10(11):2599) — Foods (MDPI), via PubMed Central, 2021. What animal digest is: chemical and/or enzymatic hydrolysis of clean, undecomposed animal tissue, with exclusions, and a named kind must match (the review summarizes the AAFCO definition). Also: poultry and mammal parts used; protease and lipase enzymes; liquid and dry forms; 'probably the most commonly used flavor enhancer'; Maillard 'meaty' and 'brothy' notes from a trained human panel; dry food is the most popular but least palatable form; typical palatant rates of 0.5–2% (dry) and 1–3% (liquid), mostly sprayed on dry food; cat and dog palatants differ; palatants for canned food may not suit dry food.
2. Reading Labels (the 'flavor' rule) — Association of American Feed Control Officials (AAFCO). A flavor name may be used when a listed ingredient provides the flavor. A food does not need a large amount of an ingredient that only provides flavor.
3. Food and Drug Administration/Center for Veterinary Medicine Report on the Risk from Pentobarbital in Dog Food — US Food and Drug Administration, Center for Veterinary Medicine, 2002. Some dry dog foods bought in 1998 and 2000 contained pentobarbital. DNA tests found no dog or cat material. FDA assumed the residues came from rendered, euthanized cattle or horses. It concluded adverse effects in dogs were highly unlikely at the levels found.
4. Appendix – Dog Food Samples Used in CVM Pentobarbital Surveys and Analytical Results (surveys of 1998 and 2000; page content current as of 21 Nov 2017) — US Food and Drug Administration, Center for Veterinary Medicine, 2017. Associations between pentobarbital and rendered or hydrolyzed ingredients: strongest for animal fat, somewhat weaker for animal digest. The sampling was not representative and was a snapshot in time, with no conclusions about dog food in general. The results do not predict pentobarbital in foods on the market today.
5. Commission Regulation (EU) No 68/2013 on the Catalogue of feed materials, consolidated text of 24 July 2022 (entry 9.6.1 and footnote on naming) — EUR-Lex, Publications Office of the European Union, 2022. The catalogue has no feed material named 'animal digest'. 'Hydrolysed animal proteins' are polypeptides, peptides and amino acids from hydrolysis of animal by-products. When the Catalogue is used for labelling, the name is supplemented as appropriate by the animal species processed (e.g., porcine, avian).
6. Hydrolyzed chicken liver and increasing crude protein levels on palatability, digestibility, and intestinal fermentation products of cats (Sezerotto et al., J Anim Sci 103:skaf173) — Journal of Animal Science (Oxford University Press), via PubMed Central, 2025. Protein hydrolysates are commonly applied to kibble as palatant enhancers. Hydrolyzed chicken liver was the only animal protein in the test diets. Cats (n=20) mostly preferred these diets over poultry by-product meal diets. The authors called the protein well digestible, but fat or energy digestibility was lower on some hydrolysate diets. They called for long-term research. The supplier funded the study and supplied the ingredient, and three authors were its employees.

Checked against these sources on 2026-10-15. Definitions are in our own words. This is a reading aid, not veterinary advice: a vet who knows your animal comes first.