Can Cats Eat Onions?

Can I Give My Cat Onions?

Anyone who has spent any time in the kitchen has come to realize that there are some ingredients that improve almost any dish you add them to. These ‘wow’ ingredients, from spices to vanilla extract, can take a bland or boring dish and turn it into something spectacular. One of the healthiest, most commonly used ‘wow’ ingredients, however, is a vegetable: the humble onion. Many of us love to eat onions in stir fries, salads, fajitas, and a wide variety of other savory dishes. And, unlike many other flavorful foods, onions are actually good for our health. We get to indulge and take care of ourselves at the same time!

Since onions are in so many dishes, our cats have many opportunities to get a taste of them, but is this a good thing? Is it okay to share onions with our feline friend? Can cats have onions?

The answer: no, your cat should never eat any amount of onions, or any food that has been prepared with onions. This food is extremely poisonous to both cats and dogs, and if they get more than a little taste, the consequences can be life-threatening. If your cat accidentally consumes onions, it is a good idea to contact your veterinarian and ask for further instruction.

Why You Shouldn’t Feed Your Cat Onions

Though this may be inconvenient, it isn’t much of a loss from a nutritional perspective. Your precious Persian may be just as cute as the average bunny, but unlike bunnies, they are far from being harmless herbivores—cats are meat-eating machines. Billions of years of evolution have resulted in housecats who are essentially lions on a small scale: cute and fluffy, but born to thrive by consuming the flesh of prey animals. Simply put, cats are obligate carnivores who are biologically ‘designed’ to meet all of their nutritional needs by eating meat.

Our own doctors are constantly telling us to eat our fruits and vegetables, but no veterinarian would recommend vegetable foods as a staple in the feline diet. Because cats have been eating strictly meat for billions of years, they no longer have any need for the chemicals found in plant foods—and, in fact, have largely lost the ability to digest them. The vitamins and amino acids cats need to thrive are not present in vegetables in the proper ratios/forms for optimal absorption.

Small amounts of certain plant foods may aid in digestion and immunity (thanks to the fiber and antioxidants), but eating a significant amount of any type of vegetable is almost certain to cause health problems. Many cats who get a large helping of vegetables will suffer from indigestion, vomiting, diarrhea, or constipation. In the long term, they may develop nutritional imbalances or even end up overweight.

But onions are far more dangerous to cats than most other vegetables. Unlike carrots and broccoli, onions are extremely toxic to our feline friends; just a small amount of onion can be enough to necessitate an emergency trip to the vet.

Things to Keep in Mind

Whether raw or cooked, onions can cause a potentially fatal condition called Heinz body anemia. In cats suffering from this condition, red blood cells become damaged and are unable to carry oxygen throughout the body. Over time, the body becomes starved for oxygen, and anemia develops. Symptoms of Heinz body anemia include sudden lethargy or weakness, fever, discolored urine (often brown or red), poor appetite, labored breathing, irregular heartbeat, and discolored skin, gums, and lips. Cats may also exhibit vomiting, diarrhea, poor coordination, and behavioral changes.

Heinz body anemia results in a lack of oxygenation that can cause irreversible damage to your cat’s vital organs, including the heart, lungs, kidneys, and even the brain. Left untreated, Heinz body anemia can cause multiple organ failure as the organs give out under the stress. Cats who have a severe case of this illness often require blood transfusions to survive.

Since Heinz body anemia is life-threatening, it requires immediate veterinary care. In general, the sooner your cat gets to the vet’s office, the better their prognosis. Cats who have recently eaten onions can often get by with fairly simple preventative care: your vet will likely induce vomiting and give them activated charcoal to minimize absorption of the toxins found in onions. If your cat is already showing symptoms of anemia, other forms of supportive care may be required.

Final Thoughts

Though many foods are not recommended for cats, onions are one of the few foods that should be avoided at all costs. This food is extremely toxic to our feline friends, and consuming even a small amount (cooked or raw) can result in a potentially fatal case of Heinz body anemia. To be safe, avoid feeding your cat onions or any food that has been prepared with onions. Before giving your cat any sort of human food, read the label to make sure that it contains no onion flavor.