Can Dog Chews Go Rancid? What Pet Parents Should Know About Animal Fats and Proteins

by Chisholm Weaver on Sep 08 2026

Quick answer: Edible dog chews and meat- or fat-coated products can develop rancid odors and flavors when their lipids oxidize. Heat, oxygen, light, time, packaging, and antioxidants all affect stability. BetterBone uses no rendered animal protein or animal-fat flavoring, removing that specific animal-fat oxidation pathway from its non-edible chew formulation.

"Rancid" is a powerful word. It is also often used imprecisely.

Meat does not become rancid simply because it is rendered, and protein itself is not the primary chemical driver of rancidity. Rancidity is mainly associated with the oxidation or breakdown of fats and oils.

A premium ingredient conversation should explain that difference rather than use fear.

What rancidity is

Lipids can react with oxygen over time. This process can create peroxides and other breakdown compounds that change aroma, flavor, color, and nutritional quality.

Oxidation is influenced by:

· Type of fat, especially degree of unsaturation

· Oxygen exposure

· Temperature

· Light

· Moisture

· Metals and other catalysts

· Antioxidants

· Packaging

· Length of storage

That is why pet foods and edible chews have shelf-life and storage instructions.

Rendered protein and animal fat are different ingredients

AAFCO explains that rendering uses heat and pressure to remove most water and fat from animal tissue, leaving primarily protein and minerals in a meal. Properly produced rendered ingredients can be safe and nutritionally useful in pet food.

An animal meal can still contain some fat, and a finished pet product may add separate animal fat or a fat-based palatant. Oxidative stability depends on the full ingredient and preservation system.

BetterBone's choice not to use rendered animal protein is a formulation preference for a non-edible toy. It is not a claim that all rendered ingredients are bad.

What research shows about oxidation in pet products

A peer-reviewed study evaluated extruded pet foods made with rendered beef meat-and-bone meal or chicken byproduct meal under different antioxidant conditions. Oxidized and rancid sensory attributes increased during storage, especially in the chicken byproduct meal formula without antioxidants. Antioxidant treatment reduced the changes.

Other research on dry dog food confirms that unsaturated fatty acids are susceptible to oxidation and that storage conditions and antioxidants affect stability.

The practical lesson is balanced:

· Animal-derived ingredients can be stable when properly processed, protected, packaged, and stored.

· Products containing fats have a real oxidation-management job.

· Removing an animal-fat ingredient removes that ingredient's contribution to the oxidation pathway.

Which dog chews are most relevant to rancidity?

Animal tissue chews

Bully sticks, ears, tendons, fish skins, and other dried animal products contain biological material and varying amounts of fat. Follow best-by dates and storage directions.

Meat- or fat-coated rawhide

The rawhide base may be treated with palatants or coatings that change the stability profile.

Edible dental chews

These formulas may contain oils, animal fat, meat meals, and antioxidants. Keep the original package and close it properly.

Meat-flavored non-edible toys

A non-edible base material may be coated or infused with animal-derived fat or protein. Ask what the flavor system contains.

Plant-based chews

Plant oils can oxidize too. "Plant-based" does not mean "cannot become rancid." The actual formula, fat content, processing, and storage determine the risk.

BetterBone's specific rancidity advantage

BetterBone's current formulation contains no:

· Rendered animal protein

· Animal-fat flavoring

· Meat coating

· Animal byproducts

· Peanuts or tree nuts, produced in a nut-free facility

Its scent infusions are vegetarian and plant-based.

This means BetterBone avoids adding animal-fat flavoring and the residual animal-derived lipids that can require oxidation control in rendered animal inputs.

The correct claim is not "BetterBone can never age, smell different, or degrade." Any manufactured product can be affected by contamination, heat, moisture, sunlight, cleaning, or improper storage.

The precise advantage is narrower and stronger:

BetterBone does not depend on animal fat or rendered meat ingredients for scent, so that animal-derived lipid oxidation pathway is absent from the formula.

How to tell when an edible chew may have a problem

FDA advises pet parents to report pet food or treat problems such as foul odor, leaking or swollen packaging, foreign objects, or illness after use.

For edible chews, stop use when you notice:

· Unexpected rancid, paint-like, bitter, sour, or stale odor

· Oily seepage or discoloration not described by the manufacturer

· Mold

· Insects

· Damaged or unsealed packaging

· Product past its best-by date

· Vomiting, diarrhea, lethargy, or refusal after use

Smell is useful but not a perfect safety test. Some contaminants are not detectable by odor.

How to store chews and treats

FDA recommends keeping pet food and treats in their original packaging in a cool, dry location below 80 F, unless the label says otherwise. The original package preserves the lot number and best-by information.

General practices:

1. Keep the package sealed.

2. Avoid hot cars, windowsills, and humid storage rooms.

3. Do not mix new product into an unwashed container holding old residue.

4. Keep chews away from household chemicals.

5. Save the lot number.

6. Wash hands and clean pet-contact surfaces.

7. Follow refrigeration instructions for perishable products.

For BetterBone, rinse with warm water and let it air dry. Do not add food spreads during a strict elimination diet unless the veterinarian approves them.

Rancidity and allergy are different concerns

A food allergy is an immune reaction to an allergen, commonly a protein. Rancidity is a chemical deterioration process involving fats.

A product can be:

· Fresh but allergenic to a particular dog

· Rancid but not related to that dog's allergy

· Both

· Neither

BetterBone's animal-protein-free formulation addresses common animal-protein exposure. Its lack of animal-fat flavoring addresses a separate oxidation pathway. They are complementary benefits, not the same claim.

Questions to ask a chew manufacturer

· Is animal fat used in the formula or coating?

· Are rendered animal proteins used?

· What antioxidants or preservation systems protect edible ingredients?

· What is the shelf life?

· What storage temperature is recommended?

· Is the scent infused, coated, or sprayed on?

· What does a normal product smell and look like?

· What lot and complaint process is available?

Quality is not only the ingredient list. It is also stability, packaging, traceability, and honest storage guidance.

Frequently asked questions

Is rendered animal protein always rancid?

No. Rendering is a controlled process, and properly produced meals can be stable and safe. Oxidation depends on residual fat, antioxidants, handling, packaging, and storage.

Is rancidity caused by protein?

Rancidity is primarily associated with fats and oils. The phrase "rendered protein rancidity" usually reflects residual lipids in an ingredient or product, not oxidation of the protein itself.

Can plant oils go rancid?

Yes. Plant oils can oxidize, especially when rich in unsaturated fatty acids. Evaluate the actual formula rather than assuming plant-based means oxidation-proof.

Can BetterBone go rancid?

BetterBone does not use animal-fat flavoring, so the animal-fat oxidation pathway is absent from the scent system. It also contains no rendered animal protein, which supports a separate allergy-conscious formulation goal. Plant-derived inputs can still age or change, so store the chew clean and dry and discard it if contaminated, damaged, or abnormally changed.

What should I do with a foul-smelling dog chew?

Stop use, keep the packaging and lot number, contact the manufacturer, and call your veterinarian if the dog is ill. Food and treat complaints can also be reported to FDA in the United States.

Is BetterBone made in a nut-free facility?

Yes. BetterBone is manufactured in a nut-free facility, with no peanut or tree nut ingredients in the current formulation.

The bottom line

Rancidity is a fat-stability issue, not a reason to label every rendered ingredient unsafe.

The premium standard is to know which fats are present, how they are protected, how the product is stored, and whether animal fat is needed in the first place.

BetterBone chooses a different path: no rendered animal protein, no animal-fat flavoring, and a plant-based scent system. That gives dogs an engaging chew without relying on meat-derived ingredients that can introduce common animal allergens, or animal-fat flavoring that adds a lipid-oxidation pathway.

That is a cleaner approach to flavored chewing.

Explore BetterBone or read Why BetterBone Doesn't Use Rendered Animal Protein.