Can cats eat onions?
Written by Meowledge · Last updated
No — raw, cooked or powdered, onion harms cats.
What to do if your cat ate onions
Contact your veterinarian or an animal poison control hotline immediately, even if your cat seems fine — hemolytic anemia can take several days to appear. Do not induce vomiting at home; a vet will look for Heinz body hemolytic anemia to confirm the diagnosis.
No. Cats should not eat onion in any form: raw, cooked, dried or powdered. Even a little cooked onion has poisoned cats, and the damage can take days to show, so call a vet now even if your cat seems fine.
- Dangerous amount
- Toxicosis has been reported in cats after ingesting less than a teaspoon of cooked onions or 5 g/kg of raw onions (Merck Veterinary Manual).
- When signs appear
- 3-5 days for hemolytic anemia to develop
- Day 0: Onion eaten. Call a vet now, even if your cat seems fine.
- The first days: Your cat may seem well: signs are generally not seen until many red blood cells have broken down.
- Days 3–5: Red blood cells break down (hemolysis), causing anemia.
Timing from the Merck Veterinary Manual.
Symptoms of onions poisoning in cats
- Vomiting
- Lethargy or weakness
- Yellow gums (icterus)
- Rapid heart rate and breathing
- Red or brown-tinged urine (hemoglobinuria)
- Collapse in severe cases
Why are onions toxic to cats?
Onion contains sulfur compounds that damage red blood cells; ASPCA names N-propyl disulfide. Chopping, cooking and chewing release them. The damaged cells break down, which causes a type of anemia (Heinz body hemolytic anemia) and methemoglobinemia. Cats are the most sensitive species, ahead of dogs.
The same damage can show later as yellow gums or urine that has turned red or brown, once enough red cells have broken. That is days after the meal, not at the bowl, which is why the call does not wait for a sick-looking cat. None of it is an allergic reaction, either: the harm Merck records is oxidative damage done to the red cells themselves, and no source here describes an onion allergy.
How much onion is toxic to a cat?
Very little. The amounts on record for cats are cases of poisoning, not safe limits. Cats have been poisoned by 5 g/kg of raw onion, while in dogs signs have followed 15–30 g/kg.
Poisonous enough to kill: Merck's record lists collapse and death among the possible outcomes, which is why these amounts are treated as an emergency, not a limit.
Can cats eat cooked onion or onion powder?
No. Cooking does not make onion safe. Merck reports poisoning in cats after less than a teaspoon of cooked onion, and says concentrated forms cause poisoning most often: dehydrated flakes, onion powder and dry onion soup mixes.
So check the ingredient list of any seasoned or ready-made food before you share it. You can look up other foods in the food list. Chocolate is on the same list of everyday dangers — see chocolate.
Are garlic, chives and leeks toxic to cats too?
Yes. Garlic, chives, leeks, shallots and green onions all belong to the same plant family (Allium), and all of them are poisonous to cats. Garlic is 3–5 times more toxic than onion.
Onions on the counter and lilies in the vase are the two classic household emergencies for a cat — lilies are treated as toxic in any amount, with no threshold at all.
When do signs of onion poisoning start?
Usually at 3–5 days. Signs are generally not seen until many red blood cells have already broken down, so a cat can seem well at first. That is why you should call before any signs appear.
Onion can also upset the stomach, causing nausea, vomiting and diarrhea. Once the anemia is underway, Merck also lists lethargy, loss of appetite, rapid breathing, panting, a fast heart rate, weakness and exercise intolerance.
How do vets treat onion poisoning in cats?
If the onion was eaten recently, the vet may start by clearing it from the gut, then treat the anemia. The diagnosis rests on what your cat ate, its signs and lab tests.
There is no safe way to make a cat vomit at home. Only trained people should do that, so the gut-clearing step belongs at the clinic, not the kitchen.
Sources
1.Merck Veterinary Manual — Garlic and Onion (Allium spp) Toxicosis in Animals
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dogs and cats have been affected after ingesting raw, cooked, dehydrated, or granulated onions and garlic... Several days after ingestion, clinical signs of acute hemolytic anemia develop... Treatment entails early GI decontamination and management of acute hemolytic anemia... Garlic is 3–5 times more toxic than onion... Cats are the most susceptible species, followed by dogs... toxicosis in these species is most commonly associated with ingesting concentrated forms of Allium, such as dehydrated flakes, powders, or dry onion soup mixes... toxicosis has been reported in cats after ingesting less than a teaspoon of cooked onions or 5 g/kg of raw onions... In dogs, ingestion of 15–30 g/kg of raw onion has resulted in clinical signs... Sulfur-containing oxidants in Allium spp are thought to be responsible for the hemolysis that occurs after ingestion... These compounds are released via mechanical disruption (chopping, cooking, chewing) of the plant... Absorption of these oxidant compounds results in oxidative damage to RBCs, Heinz body formation, and methemoglobinemia... Hemolysis typically occurs 3–5 days after exposure... Clinical signs of Allium spp toxicosis are generally not noted until substantial hemolysis has occurred, usually a few days after exposure... Lethargy, anorexia, tachypnea, tachycardia, weakness, exercise intolerance, icterus, hemoglobinuria, collapse, and death may occur... Diagnosis of Allium spp toxicosis relies on patient's history of exposure, clinical signs, and clinicopathological confirmation of Heinz body hemolytic anemia... GI decontamination in cases of recent ingestion is recommended... Ingestion of raw, cooked, or concentrated forms of onions and garlic can result in Heinz body hemolytic anemia in cats, dogs, and food-producing animals... clinical signs of anemia may take as long as several days to appear
2.ASPCA — Toxic and Non-Toxic Plants: Onion
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Toxic Principles: N-propyl disulfide... Vomiting, breakdown of red blood cells (hemolytic anemia, Heinz body anemia), blood in urine, weakness, high heart rate, panting... contact your local veterinarian as soon as possible
3.Pet Poison Helpline — Onions Are Toxic to Dogs (and Cats)
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Alternate Names Chives, Garlic, Green Onions, Leeks, Shallots... Onion, along with chives, garlic, and leeks, belong to the Allium family; all are poisonous to dogs, cats, and livestock... Poisonous doses of Alliums damage red blood cells leading to anemia and cause GI distress with nausea, vomiting and diarrhea
4.Pet Poison Helpline — Why You Should Not Induce Vomiting in Cats
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Only trained medical professionals should induce vomiting in your pet... There is simply no safe way to induce vomiting at home with cats.
How sources are picked: methodology. Spot an error? Email hello@meowledge.app.