Cats often do not eat a full serving of their canned cat food at one sitting. Sometimes there either isn't enough time, or other times owners forget to pick up the uneaten portion. How long can you safely leave canned cat food out?
The length of time you can leave canned cat food out depends on room temperature. In the summer, lacking air conditioning, leave the food out no longer than 20 minutes, maximum.
Likewise, in the winter, if the heater is on, or the food is in a warm kitchen, 20 minutes would apply. The absolute maximum under optimum temperature would be around 30 minutes.
Kittens, who should be given smaller meals more frequently, probably will finish their meal well before 15 minutes. It's better to give them only a tablespoon or two every three hours than to take a chance on spoiled food.
Air is Bad
Exposure to air also means exposure to bacteria. Keep the food storage container closed and as airtight as possible. The second is moisture as too much will lead to mold. Last is temperature. Don’t store pet foods (even unopened bags or cans) in the garage or shed where temperatures can go above 100 degrees Fahrenheit. Most manufacturers recommend storing kibble and canned foods in a cool, dry place. The kitchen pantry or an inside closet works great.
Canned food remaining in the can should be covered and refrigerated immediately after opening, and the next serving can be warmed, as most cats don't like cold food.
You can use zippered disposable bags for storing uneaten food. They can be readily warmed with running water in the sink for a few minutes. An alternative would be to put the next serving in a microwavable dish, cover with plastic wrap, and warm on a low setting for a short time. You don't want to heat the food, but warm it to room temperature.
Cat food expiration dates (sometimes known as “best by” or “use by” dates) are established to ensure the safety of your cat. Don’t take the risk by feeding your pet expired cat food.
Dry Food Can Also Go Bad
Dry food is convenient, but when it sits around it can lose some of its nutrients and can even go bad. Store dry cat food in an airtight container away from light. Dump it once it’s past the expiration date. Although it may be more convenient to open a bag of kibble and dump it in a metal or plastic trash can for storage, discarding the original bag isn’t a good idea. The bags are designed to keep the foods good, without spoilage, for quite a while. (Check the ‘sell by’ or ‘use by’ date on the bag.) The original bags also keep the fats in the food from soaking through and thereby turning rancid. Plus, if there’s a problem with the food later, you’ll want the information that’s on the bag, especially the lot number. Once the bag is opened, roll the top to close it, and use a clip or clamp to keep it tight.