Is it Safe for Dogs to Eat Expired or Leftover Food

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There are so many different brands, types, and flavors of dog food on the market that picking one can be overwhelming. Feeding your pup a healthy, nutritious food doesn't stop once you make an educated decision on what to feed, though. Knowing how to properly store your dog's food to prevent spoilage, being aware of the signs of contamination, and understanding the difference between a 'best by' date and an expiration date are all important aspects when it comes to your pet's nutrition.

Best By vs. Expiration Dates

Best by dates and expiration dates are not synonymous. An expiration date denotes when the food item has 'turned' and is no longer safe to eat. A best by date, on the other hand, is the date in which a pet food item isn't as nutritionally complete as the label may say. It doesn't always mean that the pet food is no longer safe, though. Most pet food will still list best by dates so that pet owners can confidently know they are feeding their pet nutritious, safe pet food.

A pet food company can gauge what the best by date for a particular food line will be based on the type of preservatives used in the food. When it comes to canned food, canning is the preservative, so unopened cans usually stay fresher longer than unopened dry food. In regards to added preservatives, there are various kinds of natural and synthetic preservatives used in pet food. While the word preservative has gained a bad reputation in recent years, they are vital in keeping your pet's food safe for consumption.

Not all preservatives have the same rate of degradation, though, and pet food companies will use this knowledge to determine how long their food is good for. Once the best by date has passed, the preservatives will begin to degrade. Once that happens they can no longer protect your dog's food from spoiling, either from mold or bacterial overgrowth.

fawn Pembroke Welsh corgi sitting on orange textile
fawn Pembroke Welsh corgi sitting on orange textile

Preservatives aren't the only ingredients that begin to degrade after the best by date, though. Micronutrients like vitamins and minerals will begin to diminish and the food will lose its nutritional value and no longer be nutritionally complete and balanced.

Dog Food Storage Best Practices

Even if you purchase a product that hasn't gone past its best by date, there is a risk for contamination and food spoilage if the food is not stored properly. The most common ways dog food can spoil is by exposure to air, moisture, or excessive heat. Exposure to air allows harmful bacteria to grow and multiply. If the food is stored in an area that has excess moisture, the pet food can grow moldy. If the ambient temperature of where the food is stored is excessively high the food can go rancid. You may not be able to tell that your dog's food has spoiled at first glance, but it may have a noticeable sour or rancid odor to it. You may also see signs of moisture or bugs in the food. Depending on how finicky your dog is, he may even snub his nose at the food if he smells something that you may not, so pay close attention to how your dog reacts to the food. If he gets excited while you are getting his breakfast ready, runs up to the bowl, and then stops dead in his tracks, hesitantly sniffs the kibble and then walks away, he may smell something off in the kibble that you may not.

Opened bags of dry dog food is best stored in the bag it came in, sealed with a chip clip and placed in an airtight food storage container. Roll the opening down in order to not leave excess air inside the bag. Pouring the kibble directly into the food storage container is not advised because you cannot limit the amount of air inside the container the food is exposed to and you cannot have the food's lot number and best by date information in the case of a recall. Dry dog food can also be stored in the freezer to further stretch its shelf life. Ideally you should use up a bag of dry dog food within a month or so of opening it.

Opened cans or pouches of wet dog food are best stored tightly covered in the fridge. Once opened, wet food should be used within three days. This is in part because there are inherently less preservatives added to the canned food (since the canning process itself preserves the food) so the nutrients will begin to degrade more quickly once opened. Similar to dry dog food, freezing can increase shelf life once opened. You can open a can of dog food, transfer to a freezer safe container, and place in the freezer for longer food storage.

selective focus photography of short-coated brown puppy facing right side
selective focus photography of short-coated brown puppy facing right side
A white dog sitting on a rock formation near a large mountain pond.
A white dog sitting on a rock formation near a large mountain pond.
long-coated brown dog
long-coated brown dog

What If My Dog Eats Contaminated or Expired Dog Food?

If your dog does happen to get into spoiled or expired dog food you may see signs of general gastrointestinal upset such as vomiting or diarrhea. Depending on the pathogen, though, your dog may become seriously ill. Bacterial pathogens like E. coli and Botulism can cause life threatening illness if left untreated. Certain species of mold can produce mycotoxins such as vomitoxin (which can cause severe disease if left untreated) and aflatoxin (which can cause death if left untreated). This is why, even though vomiting and diarrhea can be a symptom of so many different ailments, it is important to have your pup checked over by your vet as soon as these symptoms arise.


If your dog is allowed to eat expired dog food for an extended period of time, you may see signs of malnutrition because of nutritional depletion. These signs may manifest as a loss in energy, weight loss, or muscle wasting.