How much onion does it take to kill a cat?

My sister fed the ferals potato salad with chopped onion in it. Not a lot-but still, it was in there. I'm worried. Any advice?

I wouldn't say it would kill them - not a once off

Health problems can occur from eating onions.

Onions contain a substance (N-propyl disulphide) which destroys red blood cells in the cat, causing a form of anemia called Heinz body anemia. Garlic contains a similar substance in a lesser amount.

They are just fine. In fact, they got a chimpmunk this morning-and that was the cat who got the most of the salad!

I think onion/garlic toxicity is a cumulative thing. If they got a small dose every day, that would be more dangerous than a large dose once.

Originally Posted by Willowy

I think onion/garlic toxicity is a cumulative thing. If they got a small dose every day, that would be more dangerous than a large dose once.

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I don't know...the cat's body would be able to repair over time, with the small repeated doses. A really massive dose all at once could completely shock the cat's system.

Hmmm, this is a quote from the info I found: "Daily feeding of onions could have a cumulative effect due to ongoing formation of Heinz bodies versus a single exposure with a wide gap until the next exposure, allowing the bone marrow time to regenerate the prematurely destroyed red cell"

Well, I'm sure a one-time feeding is better than repeated feeding for a given amount. I just think that a one-time large dosage, at some point, would have to be worse than a small daily dose.

Onions  contain an ingredient called thiosulphate which is toxic  to cats  and dogs. The ingestion of onions  causes a condition called hemolytic anemia, which is characterized by damage to the red blood cells. Onion toxicity  can cause the red blood cells circulating through your pet's body to burst.

ria1999 said:

Onions contain an ingredient called thiosulphate...toxic to cats and dogs.... Ingestion of onions causes...hemolytic anemia...damage to the red blood cells...can cause the red blood cells circulating through your pet's body to burst.

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And if enough of them burst there won't be enough viable cells to carry oxygen from their lungs to the rest of their body ... and they *can* suffocate.

I don't think a single incidence will hurt them, although onions aren't good for cats. Mine got into the potato salad too one time and ate quite a bit of it. I watched them pretty close and they didn't have any problems.

Won't turn my back on my potato salad while I go get a sandwich any more, though!

I'm pretty sure that I read it can take up to 5 days before there's evidence of a problem in a cat that has eaten sufficient onion to cause harm, to present with symptoms. By then the damage is done.

The big problem is that those affected red blood cells aren't around to do their oxygen-transporting job until the cat's body can make new ones. That takes time. What do they do for an affected cat in the meantime? Make a blood transfusion?