How long does cat food last and when is it no longer good any more? There are several different opinions about how long pet food lasts beyond the “Best By” date that should always be printed on canned and dry pet food. In this article, I will try to provide information that is important to understanding the “Best By” dates, and why you want to pay attention to and follow the “Best By” date on your cat food packaging.

“Best By” Dates

First, always check the “Best By” date stamped on both canned and dry cat food when shopping at your local pet food store. It’s usually printed at the bottom of canned food with the month/year and printed on dry food bags on the side toward the bottom of the bag. Often they say “Best By” which means the food is most potent and effective being used by that date and will provide the nutritional value that is stated in the Guaranteed Analysis—up to that date. This date, however, is not the manufactured date, so there is no real way of knowing how old the food is or when it was produced unless you contact the manufacturer directly. Food is always freshest when it is first produced and new, so as a consumer you want to check to see you’re buying it well in advance of the “Best By” date.

You would expect that most pet food stores would carry food that has time to go well before the “Best By” date posted, and would pull their food if the “Best By” date is reached—but stores vary, so always check the dates anyway. Manufacturers set the “Best By” date to indicate the date the food will maintain its optimum nutritional value and potency, flavor and taste. After this date, the food is not suddenly bad, but the quality and nutritional value and potency will fade and you won’t be giving your pet the nutrition on the label any longer.

Types of Preservatives & Shelf Life

For one, the type of food preservative used will affect the shelf life of the food. Artificial preservatives such as BHT, BHA, and ethoxyquin will lengthen the life of pet food. But these preservatives are also considered by some research reports to be more harmful to your pet’s health over time. Natural preservatives such as Vitamin E will have a shorter shelf life, but are better for your pet’s health and not harmful. But all preservatives degrade over time and become less effective, so best to use the “Best By” date as your guide and toss the food out on or close to that date.

Storing Pet Food

Both oxygen and heat damage the shelf life of pet food and deplete vitamins, weaken the nutritional value, and diminish the flavor. They lead to oxidation of the fat in the food, which makes the food rancid and rancid food can be dangerous for your pet to eat and lead to serious illness. Both dry and wet food should always be stored at room temperature in a cool and dry storage place. Once canned food is opened it should immediately be covered tightly then stored in the refrigerator and used within 2-3 days. The best covers are those made for the cans available at pet food stores, veterinarian offices, and grocery stores—but you can use plastic-wrap like Saran™ wrap too. Ziplock bags are less effective at keeping oxygen out.

Proper storage is critical and includes avoiding extreme heat (above 80-90 degrees F), and avoiding damp and humid spaces like in basements, bathrooms or garages, since moisture can trigger the growth of mold.

Keep dry food in its original packaging sealed tightly, then I recommend putting the dry food package inside of another larger plastic or metal container that has a lid that can be sealed tightly again to keep rodents and insects out, protect the food from oxygen and light, and prevent any contamination or degradation from occurring.

Storing food in an uncontrolled environment like in your garage can mean subjecting it to too much heat or cold, pest infestation, or moisture.

Is “Best By” the Same As “Expired By?”

Pet food manufacturers don’t say “Expired By” on their packaging, which would be a clearer indication of when pet food is clearly too old and unsafe to use. Most packaged food for humans just displays a stamped date, and after that date we know to toss it. Packaged goods companies provide a date that they can best and safely guarantee the food is safe, but beyond that the food becomes more of a risk.

Like human food, you would not want to risk your pet’s health and safety, so it’s best to follow the manufacturer’s guidelines and toss the food after the “Best By” date is reached, the further you wait and keep the food beyond the “Best By” date—the riskier it can be for your pet to eat and they will not be getting the stated nutritional value.

If you do buy pet food from a retail store beyond the “Best By” date, bring it back and get a refund or ask to replace it with a food within the expiration date. Let the store manager know to pull the expired food, to avoid selling it to another unsuspecting customer.

Remember what you feed your pet is critical to their health and well-being, and how and where you store your pet food is very important to keeping the food safe, and since pet food after the “Best By” date is in question regarding its nutritional value, quality and flavor—discard it by or just after that date to be on the safe side. Then you never have to worry about your pet’s health and safety.