It’s natural for cat owners to want to share tasty treats with their feline companions. While some human foods are safe for cats in moderation, it’s crucial to know which ones pose a threat. Onions are a common ingredient in many human meals, but are they safe for cats? The definitive answer is no. Cats should never eat onions in any form.
Onions, along with other members of the Allium family such as garlic, chives, and leeks, are toxic to cats. While onion poisoning is also a concern for dogs, cats are significantly more vulnerable to its harmful effects. Understanding why onions are dangerous and what to do if your cat ingests them is vital for every cat owner.
Why Are Onions Toxic to Cats?
While a curious cat might occasionally nibble at a raw onion, it’s more common for them to ingest onions hidden within other foods. Whether cooked, raw, or powdered, onions remain toxic to cats. This means keeping your feline friend away from dishes like sauces, soups, gravies, pizzas, and anything else that might contain onions. Even onion powder, often found in seasonings and processed foods, is equally – or even more – dangerous than fresh onions.
Onion toxicity in cats stems from compounds that cause significant gastrointestinal distress and, more seriously, damage to red blood cells. This damage can lead to the rupture of red blood cells, resulting in life-threatening anemia. Red blood cells are essential for carrying oxygen throughout the body. When these cells are destroyed, a cat’s body is deprived of oxygen, impacting vital organs like the lungs, liver, and kidneys.
How Much Onion is Poisonous to Cats?
The toxic component in onions and other Allium plants is called N-propyl disulfide. This compound is responsible for the harmful effects of onion ingestion in cats. While even a small amount of onion can cause stomach upset, severe poisoning occurs when a cat consumes more than 5 grams of onions per kilogram of their body weight, or 0.5% of their body weight in kilograms. This is considered the toxic dose, but cases of onion toxicity have been reported in cats after consuming as little as one teaspoon of cooked onions.
It’s critical to remember that onion powder is far more concentrated than fresh onions. This means even a tiny amount of onion powder can be toxic to cats. To put this into perspective, a medium-sized onion weighs roughly half a pound (226 grams) and is equivalent to about 1 tablespoon of onion powder. This highlights the potent danger of onion powder in a seemingly small quantity.
Recognizing Onion Poisoning Symptoms in Cats
The signs of onion poisoning in cats may not be immediately apparent. Symptoms can be delayed, appearing only after a considerable number of red blood cells have been damaged. Anemia can develop as quickly as 12 hours after onion ingestion, but it typically manifests within two to five days post-exposure.
The most frequently reported symptoms of onion poisoning in cats include vomiting, diarrhea, and lethargy. However, other symptoms can also indicate onion toxicity:
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Early, Non-Specific Signs:
- Nausea
- Excessive drooling (ptyalism)
- Oral irritation
- Abdominal pain
- Vomiting
- Diarrhea
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Signs of Anemia and Potential Organ Damage (Liver and/or Kidneys):
- Pale, yellow, blue, gray, or brown gums and mucous membranes
- Lethargy and depression
- Increased heart rate
- Rapid, shallow breathing
- Weakness
- Exercise intolerance
- Dark-colored urine
- Jaundice (yellowing of skin and eyes)
- Collapse
- Seizures
- In severe cases, death
What to Do if Your Cat Eats Onion
If you know or suspect your cat has eaten onion, or food containing onion, immediate veterinary attention is crucial. Contact your veterinarian or an emergency animal hospital without delay. The sooner your cat receives medical care, the better their chances of recovery.
It’s also advisable to contact a pet poison helpline, such as the Pet Poison Helpline at 855-764-7661 (US), to consult with a veterinary toxicologist. They can provide specific guidance on how to manage your cat’s onion exposure. Prompt veterinary intervention is key to treating onion poisoning and minimizing red blood cell damage.
Treatment for Onion Poisoning in Cats
Treating onion poisoning in cats often requires hospitalization. Your cat may need to stay at the veterinary clinic until the extent of red blood cell damage is assessed and treated.
If onion ingestion is recent (within the past couple of hours), your veterinarian might induce vomiting to remove any remaining onion from the stomach. They may also administer activated charcoal and other decontamination treatments to limit toxin absorption into the bloodstream. Never attempt to induce vomiting at home unless explicitly instructed to do so by a veterinarian, as it can be harmful if done incorrectly.
Your vet will perform regular blood tests to monitor your cat’s red blood cell levels and determine if a blood transfusion is necessary. Additional blood work and urine tests will be conducted to evaluate the function of other organs, such as the liver and kidneys, for signs of toxic damage.
During hospitalization, your cat will likely receive intravenous fluids and medications to manage gastrointestinal symptoms and support liver function. In cases of severe anemia, supplemental oxygen therapy might be required to compensate for reduced oxygen-carrying capacity due to red blood cell loss.
Cats that recover from onion toxicity will need ongoing monitoring of their red blood cell counts for several weeks. With prompt decontamination and medical treatment, the prognosis for cats with onion poisoning is generally favorable. However, the prognosis is less optimistic for cats with severe anemia, liver failure, or those who do not receive timely and aggressive treatment.
References
- A pungent poisoning: Onion toxicosis in a cat. DVM 360. Accessed May 2, 2023. https://www.dvm360.com/view/pungent-poisoning-onion-toxicosis-cat
WRITTEN BY:
Barri J. Morrison, DVM
Veterinarian
