Four Signs That Your Dry Cat Food Is Bad




a cat saying "Four signs that your dry cat food is bad"

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Dry cat food is an affordable and convenient option for your cat. It is easier to feed to your cat and it lasts much longer than wet food. But just how long? You may have found half a bag of cat kibbles in the back of the cupboard and are wondering if it would do any harm feeding it to you cat.

If dry cat food pellets smell rancid, feel soft or there is mold or dust on them, they have gone bad. Unopened, dry cat food can store for 6 months in a cool, dry, dark place. But once opened, it must be used in 14-21 days, after which it will start to go rancid and stale.

Naturally, you want to make sure that your cat is eating a diet that is nutritious and healthy for them. Choosing a high-quality brand of food is only the first step. How you store dry cat food impacts its flavor, texture, and nutrient profile. How can you tell if your dry cat food is bad?

Can dry cat food really spoil?

While feeding your cat dry food is very convenient because it lasts longer than wet food, it does not mean that dry cat food is immune from going bad. Just like a box of crackers that is left open near the back of the pantry absorbs moisture from the air and goes stale, as does an opened bag of dry cat food. Dry cat food also contains protein and oil that goes rancid.

All commercial dry cat foods contain preservatives and antioxidants, that maintain the flavor, texture, and nutrient profile of the food. After the expiry date, the preservatives begin to degrade, lowering their efficacy, increasing the risk of mold and bacteria growing in the food.

High quality cat goods are preservative free, making them go bad even faster. Store your cat’s expensive food correctly to avoid wasting it, and to ensure that your kitty is getting all the possible nutrients from their food.

Even if dry cat food still looks and smells fine after the expiry or “best by” date, the food will be lower in quality nutritionally, due to the natural breakdown of fatty acids and preservatives. Feeding your cat expired food is dangerous to their long-term health because it can lead to nutrient deficiencies.

How to tell if dry cat food has gone bad

  1. Looks funky. Are there little creepy crawlies or mold on the food? Some biodegradable packaging types are permeable, meaning that insects and other pests may get in. Do the pellets look unusual? If you are brave, pick a pellet up and squeeze it. If it feels softer than normal or slightly moist, it might have gone bad.
  2. Smells rancid. Dry cat food pellets are coated in oils and fats. We all know what happens if an oil, like butter is left out of the fridge on a hot day – it goes rancid! If exposed to high temperatures, fatty acids and vitamins in the food are oxidized and destroyed and the food becomes rancid. It gets a sour, off-putting smell. Give the food a sniff to check. If the bag has been open for more than three weeks, it has probably gone bad.
  3. Check the expiry date. Has it been sitting on the shelf for a long time? Is there dust on the bag? Look on the bag for an expiry date (there may only be a “best by” date). This date indicates how long a product has been designed to store for. Past this date preservatives will start degrading and the nutrient profile of the food will change. Mold and microbes will start to grow. Even if the food looks and smells fine, if it has expired, do not feed it to your cat.
  4. Your cat refuses to eat it. Cats are generally very fussy eaters and will let you know, if you cannot decide, whether their bag of dry food is still good. Place some of the pellets in a bowl next to another bowl with some fresh pellets. If your cat only eats the fresh food, throw out the old bag. If they nibble from both, the food is still good.

How long does dry cat food last once opened?

Unopened, a bag of cat food lasts for six months. However, once it is opened, it must be used within three weeks to a month at most. This is if you store the food correctly!

Most cats prefer to eat small meals throughout the day, so one can leave their pellets out for them all day. It is not safe to do this with wet food. The dry food in the bowl can get soggy and stale after a day of standing out. If there is food left in their bowl after a day, you should toss it out before putting fresh food in.

Store dry cat food correctly

It is a good idea to keep the cat food in its original packaging, with the barcode, batch number and expiry date. That way, if the manufacturer issues a product recall, you can check your bag! Another good reason to keep it in its original packaging is that the plastic has been designed to retain freshness, flavor, and moisture.

Keep the bag sealed so that the food is exposed to air as little as possible. Most good quality cat foods are packaged in plastic bags with resealable zips. Always reseal the bag and store in an airtight container. Prevent exposure to humidity, which speeds up the rate fatty acids are oxidized and increases the risk of bacteria contaminating the food. Keeping it in a plastic box has the added benefit of keeping the food safe from cats, who will scratch at the bag and make a mess trying to get more snacks.

Even before opening dry cat food, it should be kept out of direct sunlight, in a cool, dry, dark place. Dry cat pellets should never be heated above 38 degrees Celsius, as vitamins will denature, making the food less nutritious. Exposing an opened or unopened bag of cat food to sunlight will increase the humidity and temperature inside the bag, increasing the risk of Salmonella and other microbes.

You may be left with a little expired dry cat food in the previous bag and just add it to the new bag, not wanting to waste it. Do not mix old and new pellets, as you risk spoiling the while new bag.


Dry cat food can go bad, just like any other food. To tell if it has spoiled, give it a smell. If it has gone bad it will smell rancid. Check the expiry date – it is important never to feed cats expired food! Examine the dry food for mold or insects that may have gotten into the package. If you are still struggling to determine whether cat food is still okay – put it in front of your cat alongside some fresh food and see if they eat it. If they refuse it, throw it out, but if they eat it, it is probably still good.

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