When To Throw Your Dog’s Kibble Away

Dog eating kibble

What’s more expensive … your dog’s kibble or the bag it comes in?

Pet food companies invest heavily into the food’s packaging. Packaging with compelling pictures and benefits are a good way to make a sale. And packaging is also critical to the safety of the kibble. Experts with PhDs develop and test the packaging that contains your dog’s kibble so it can sit on the shelf for months or years and still hold much of it’s nutrition. And if they get this wrong, dogs get sick.

But their job ends when you open up that bag of kibble. As soon as you open that bag of kibble, the food changes quickly. And those changes can be toxic to your dog if you’re not careful.

In today’s article, let’s take a look at how long that bag of kibble really lasts and why.

How To Make Dog Food Last For Three Years

The main reason kibble is heated and dried is to remove the moisture from the food. Moisture is the enemy of any food that needs to sit on a shelf for months or years because moisture breeds bacteria. So most kibbles contain only about 10% moisture.

Once the kibble is dried, the packaging is critical to the stability of the food. If air were to get into the food while it sits on the shelf, then something called oxidation would occur. Oxidation happens when the chemicals in the food come into direct contact with oxygen. The result is a decrease in the nutritional value of the food. Oxidation can also cause mold and bacteria to grow in the food.

The most sinister result of oxidation is what happens to the fats in the food. But luckily, modern day packaging has a grease barrier that usually contains a synthetic antioxidant and this prevents the fats from oxidation and becoming rancid.

So with the proper packaging in place, the pet food manufacturer can send that food out on pallets and it will sit on the shelf with a “Best Before” date so you can feel safe knowing the food you buy your dog isn’t spoiled.

As an aside, while AAFCO requires pet food companies to put a “Best Before” date on your food, they don’t require the companies to say when the food was manufactured. So you really have no way of knowing how long the food has been sitting on the shelf before you buy it.

But because the packaging is such an important part of keeping that food safe from the harmful effects of oxygen, what happens when you open that bag?

Why Fats Can Harm Your Dog

The minute you open your dog’s bag of kibble, air gets in and the oxidation process begins.

And every time you open the bag, the amount of oxidation increases, along with the health risks.

The fats and oils in the food are very susceptible to oxidation and every time that bag is opened, the fat particles break down into smaller compounds such as malondialdehyde, and the fat becomes rancid.

Why is this a problem?

1. Rancid fats can destroy vitamins, which can lead to vitamin deficiency. Most dogs today are vitamin D deficient – is there a link?

2. In lab studies, dogs and other mammals suffered vitamin, fat and protein deficiencies when they were fed diets with rancid fats.

3. Many other health issues have been attributed to rancid fats including malnutrition, hair loss, diarrhea, liver and kidney disease, reproductive problems and even cancer and death.

So it’s very important to prevent your dog’s food from oxidation.

The Type Of Fat Matters Too

There are many types of fats and they’re divided into the number of carbon bonds they contain. And the more carbon bonds the fat contains, the more quickly it will oxidize.

Saturated Fats, like those found in beef, contain no carbon bond. So they’re not as unstable as other fats.

Monounsaturated Fats contain one double bone, making them more susceptible to oxidation. Olive oil would be an example of a monounsaturated fat. But the amount of oxidation isn’t nearly as much as PUFA’s, or polyunsaturated fats.

PUFAs, as their name implies, contain several carbon bonds. Chicken fat contains PUFAs, making foods with chicken or poultry fat more likely to oxidize than those with beef.

The fats with the most bonds are DHA and EPA … the fats found in fish oils.

One of the most dangerous trends in the pet food industry today is adding fish oil to kibble. Even if it’s not oxidized and rancid after the kibble is processed, it will become rancid extremely quickly once the bag is opened and your dog’s health will be at risk.

Kibble pet nutrition facts label

Never buy kibble with fish oil added. If you want to give your dog fish oil, by it separately and add it to his diet but never feed him a kibble with fish oil already in it – it’s virtually guaranteed to be rancid.

RELATED: Learn more about fish oil and oxidation … 

Antioxidants: Keeping Things Fresh

Pet food manufacturers are aware of the issue of oxidation. So they use antioxidants to slow down the rate of oxidation.

Antioxidants will be added to your dog’s kibble in two forms:

  1. Antioxidants that your dog’s cells can use to help protect against the free radical damage rancid fat causes, and
  2. Antioxidants your dog can’t use but work as preservatives in the food. If an antioxidant is used, AAFCO requires the pet food company to use the common name of the antioxidant, along with the fact that it’s used as a preservative, like on the label below.
Kibble ingredients label

Antioxidants can be either natural or artificial. The type of antioxidant in your dog’s food really matters.

Synthetic Preservatives

Synthetic antioxidants are a controversial addition to pet foods and most better brands have stopped using them because of their impact on health.

There are four common synthetic antioxidants:


You might not know it, but ethoxyquin not only keeps pet food fresh, but it’s also a pesticide!

Although ethoxyquin is not approved as a direct food additive in foods made for human consumption, it’s still found in pet foods.

The allowable amount in human foods is .5 to 5 ppm but the level allowed in pet foods is 75 ppm.

This is a controversial additive and pet owners have been reporting liver and health issues to the FDA for years. The FDA   asked Monsanto, one of the major manufacturers of ethoxyquin to study the food and they reported that higher diseases could change liver enzymes.

But an independent report from the EPA (Environmental Protection Agency) claims that dogs are more susceptible to ethoxyquin toxicity than the rats Monsanto used in their study.

They found elevated liver enzymes at just 4 mg/kg/day over a 90 day feeding period. which is the equivalent to 160ppm, which is just barely above the upper limits allowed in pet foods.

The important part is that the cumulative effects of eating ethoxyquin past 90 days wasn’t considered in any of the studies.

And what about puppies, nursing dams or working dogs eating that food? They eat more food per body weight than the average dog, so it’s safe to assume they would exceed the “safe” limits.

Here’s another interesting fact …

If your dog’s food contains fish meal, it contains ethoxyquin. Ethoxyquin is required by law when transporting fish meals.

But because the ethoxyquin isn’t added directly to the pet food, AAFCO doesn’t require the manufacturer to put it on the ingredient list. Ethoxyquin can also be added to poultry meals.

Pet food manufacturers can apply for a special permit that allows them to use natural preservatives instead – so it’s best to ask the manufacturer directly for proof. If they don’t provide proof of natural antioxidants, don’t buy the food).

Kibble ingredients label


Both BHA and BHT are artificial preservatives that have been linked to cancer in lab animals. BHT is also suspected to cause developmental defects and thyroid changes.


TBHQ, or tertiary butylhydrquinone, is an antioxidant that’s derived from butane. It’s also used to make varnishes and paints.

TBHQ has been found to cause stomach tumors and it’s also been linked to many other forms of cancer. (Tertiary butylhydroquinone, safety summary from The International Programme on Chemical Safety ↩    and Gharavi N, El-Kadi A (2005), “Tert-Butylhydroquinone is a novel aryl hydrocarbon receptor ligand”, Drug Metab Dispos 33 (3) ↩

Natural Preservatives

Natural preservatives, such as vitamin E (which is usually called mixed tocopherols) and vitamin C (normally called ascorbic acid) are used in better quality foods.

But while natural preservatives are less toxic than their synthetic counterparts, they don’t offer the same shelf life.

And while they’re less toxic, not all “natural” preservatives are, well, natural!

Some of the more common natural antioxidants include:

Mixed Tocopherols

These are technically synthetic as they’re isomers of vitamin E extracted from vegetable oils and restaurant grease. The most effective tocopherol is gamma-tocopherol, which is derived from cereal grains and oils.

Want to learn more about synthetic vitamins and how they can impact your dog’s health? Read this article for more details.

Rosemary Extract

Rosemary extract is the oily residue derived from the leaves of the rosemary plant. Rosemary extract prevents the oxidation of fats and protects flavors.

Most industrial plants use solvents such as acetone, hexane or methanol to extract the oil. Rosemary extract is added to fat as a blend or premix, which can also contain mixed tocopherols, citric acid, emulsifiers and a vegetable oil carrier.

Citric Acid

This is produced by the fermentation of crude sugars. Citric acid is generally recognized as safe (GRAS) and is used in both the human and pet food industry.

Instead of using synthetic vitamin E and C or rosemary extract, some pet foods will choose to use fruits containing citric acid, such as cranberries, blueberries or apples to defend against oxidation.

How Long Will Kibble Last Once It’s Opened?

If you feed your dog kibble, it’s incredibly important to know that the “Best By” date only applies to unopened bags of food.

Once the food is opened, it loses its nutritional value and the fats begin to oxidize. And every time it’s opened, the problem is worse.

So how do you keep your kibble as safe as possible?

Here are some hints to make sure your dog is getting the best nutrition possible.

Know How Your Dog’s Kibble Is Preserved

If you’re looking for food-based preservatives instead of synthetic chemicals and vitamins, then good for you!

But you need to know that your food won’t last as long.

Know The Fat Source

How long your pet food lasts once it’s opened depends on where the fats are from. If your dog’s kibble is beef, then you need to use the bag up within 3 weeks.

If your kibble is chicken or other poultry, the PUFAs are less stable and the food should be used within 2 weeks of opening.

Don’t Buy Big Bags Of Food

It’s true that larger bags of food will cost you less, but your dog needs to get through that bag in 2 to 3 weeks before it goes rancid.

Don’t Buy Kibble With Fish Oil Or Omega-3 Fats Added

Fats from fish and fish oil oxidize very quickly. If you must feed a food with fish, use it up within a week for best results. 

Never Take Your Kibble Out Of The Package

Remember, most pet food makers spend more on the package than the contents, and that bag is designed to keep oxygen out. If you must keep your food in a plastic bin, put the bag in the bin, squeeze as much air out of it as you can and use a clip to seal it.

Bonus Tip

Why not skip the kibble altogether and feed your dog a fresh food diet instead? Then you don’t need to worry about rancid fats and synthetic ingredients!

Check out our free raw food recipes and start making save and balanced meals for your dog today. Download now >>


Pavcek PL, Shull GM. Inactivation of biotin by rancid fatsJournal of Biological Chemistry. 1942;146(2):351-5.

Quackenbush FW. Toxicity of rancid fatsJournal of American Oil Chemists’ Society. 1945;22(12):336-8.

Greenberg SM, Frazer AC, Roberts B. Some factors affecting the growth and development of rats fed rancid fats. The Journal of Nutrition. 1953;50(4):421-40.

Brown S. Better Fats, Better Dogs. Presentation presented at; 2015; NCHS. 

What is TBHQ … and is it safe for your dog. Dog Food Advisor. 

Najjar S. Health effects of rancid fatNutrition Nuts and Bolts. 2012. 

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