Onion Poisoning in Cats: Everything You Need to Know

Onions and garlic contain substances that are toxic to cats. As little as 5 grams of onion per kg of body weight can be dangerous and it does not matter if the onion is eaten raw or cooked. Garlic can be up to five times as toxic, ie the poisoning dose even lower.

In onion poisoning, the cell wall of the red blood cells is damaged, which leads to degradation of the blood cells, so-called hemolytic anemia. It can also cause gastrointestinal upset. If the cat regularly eats small amounts of onion or garlic, this can also cause poisoning.


Symptoms of onion poisoning are somewhat delayed and usually appear a few days after ingestion. Then nausea, vomiting, diarrhea, salivation, weakness / impaired condition, impaired general condition, abdominal pain, increased heart rate and respiratory rhythm and pale mucous membranes are seen. Seizures and deaths also occur. If the cat often eats smaller amounts of onions, symptoms of anemia can appear more gradually over a longer period of time, in the form of pale mucous membranes, reduced fitness and increased heart rate and respiratory rhythm.


The medical history, with information that the cat has eaten onions, gives the veterinarian important clues. When a cat comes to the vet with the above symptoms, both clinical examination and analysis of blood samples are usually done. Analysis of the blood picture shows that the cat has anemia and typical changes in the red blood cells can be observed under a microscope. Gradually, deviations in the cat’s liver values ​​are also seen.


For the next 1-3 hours after ingestion, you may try to induce vomiting in the cat by injecting a sedative that often has vomiting as a side effect. NOTE – do not try to induce vomiting yourself with the help of salt, as this can lead to life-threatening salt poisoning. The cat can also be given activated carbon to prevent the toxic substances from being absorbed into the body.

When the cat has developed symptoms, the treatment is symptomatic, and consists of intravenous drip, oxygen supply and in severe cases, blood transfusion.


If the right treatment is started early, the prognosis for complete recovery is good. Untreated onion poisoning can, however, be fatal in the worst case.


Avoid giving your cat food that contains raw or cooked onions or garlic. Also as an ingredient in other dishes, such as minced meat sauce or pudding in a pan, the amount can be large enough to be dangerous, as well as food spiced with onion powder or garlic powder should be avoided.

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