Can my pet eat Onions?

August 25, 2023
This article is not intended to be a substitute for professional veterinary advice, diagnosis, or treatment. Always seek the advice of your veterinarian with any questions you may have regarding your pet’s care, treatment, or medical conditions.

Can my dog eat onions?

Onions and dogs do NOT mix. Onions contain a substance called thiosulfate, which is extremely toxic to canines. (Other foods from the allium family of plants — including garlic, leeks, shallots, and scallions — are also extremely unsafe for dogs.)

If your dog eats onions, it can lead to a condition called hemolytic anemia, which causes red blood cells in your dog's body to burst. Hemolytic anemia can cause symptoms such as weakness, lethargy, vomiting, diarrhea, and even death.

Onions are found in many human foods — soups, pizza, salads, you name it — which means you have to be exceptionally careful about which human foods you feed to your dog as a treat. Foods are safe suddenly become dangerous if they're topped or seasoned with onions. (Onion powder and dehydrated onions are just as dangerous as any other types of onions, FYI.)

Even small amounts of onion can have severe negative effects on your dog's health. Symptoms may take several days to appear after ingestion, so it's important that pet parents monitor their dogs carefully after feeding them any new food. If you know your dog has eaten onions, get them to the vet immediately, even if they're asymptomatic. Your vet may need to induce vomiting or administer treatments like activated charcoal. The sooner your dog is treated the, better.

If your dog requires veterinary treatment due to eating onions (or any other unsafe food), pet insurance can help cover the cost of treatment.

Can my cat eat onions?

Onions are toxic to cats; your cat should never eat them, even in tiny portions or as a seasoning. Onions contain a compound called thiosulfate, which can cause a condition called hemolytic anemia in felines. This is a potentially life-threatening illness where red blood cells get destroyed faster than they're produced. Unlike humans, cats (and dogs!) lack the enzymes required to break down the thiosulfate present in onions.

Other foods from the allium family of plants — including garlic, leeks, shallots, and scallions — are also extremely unsafe for cats.

Even small amounts of onion can have serious consequences for your furry friend, with symptoms including lethargy, vomiting, diarrhea, panting and discolored urine. If left untreated, onion toxicity could lead to more severe complications like liver damage, organ failure, or death.

Onions are found in a lot of human foods, so you need to be careful about which foods you're feeding to your cat as treats. Even foods that are safe when served plain will instantly become unsafe if they're topped or seasoned with onions. And onion powder and dehydrated onions are just as dangerous as other types of onions.

If you know your cat has eaten onions, get them to the vet right away, even if they're asymptomatic. Your vet may need to induce vomiting or administer other treatments. The sooner your cat is treated, the better.

If your cat requires veterinary treatment due to eating onions (or any other unsafe food), pet insurance can help cover the cost of treatment.

Information Purposes Only

The suggestions offered here are for informational purposes only and are not a substitute for pet-specific advice from your veterinarian. Never disregard your vet’s recommendations, or delay in acting on them, based on something you have read on this site. Regardless of how a food is rated here, any food that you give your pet can pose potential health risks, including allergic reactions, choking, or other health conditions such as bloat. Always monitor your pet while they’re eating, and never introduce a new food into your pet’s diet without first consulting your veterinarian. 

Pet Poison Emergency Protocol

If your pet is acting sick, call your regular veterinarian immediately. If your regular veterinarian is closed, call a nearby on-call veterinarian, animal urgent care, or veterinary emergency hospital. If your pet is not acting sick but you think they may have been exposed to a poison, call the ASPCA Animal Poison Control Center (888-426-4435) or Pet Poison Helpline (855-764-7661).

Food Safety Statuses

Safe

Could be given almost daily without harm

Safe in moderation

Not toxic, but should not be given regularly

Unsafe

Toxic or simply too risky to give to your pet