Today I Discovered Why Onions Make Humans Cry (And Pets Ill)

Today I Discovered Why Onions Make Humans Cry (And Pets Ill)
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Cutting onions is one of the easiest ways to make yourself cry and feeding them to your pet will make them extremely ill. The same chemical compounds are responsible for both adverse reactions.

Onions produce sulfur compounds including thiosulfate as a defense mechanism to stop bugs and other pests from eating them. Not just onions but all plants in the allium family including garlic, leek and chives.

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Unlike our eyes, our red blood cells are well-equipped to deal with sulfur compounds but cats and dogs don’t eat these types of vegetables in the wild. Cats and dogs never developed a way to deal with them so now that they have been domesticated, pets can be exposed to onions in their food which lets thiosulfate into their blood stream causing anemia and rupturing of red blood cells.

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Even low doses of onion can cause severe issues for your pets. Just 5g/kg of onion is enough to cause severe reactions in your pet.

If you suspect your cat or dog has eaten onion you should induce vomiting within the hour. It can take several days to notice the effects of onion poisoning in pets and they will show signs of lethargy, vomiting, laboured breathing and red urine.

From there the damage to their blood cells can prove fatal. So you should take your pet to the vet immediately if you suspect any form of poisoning.

This article has been updated since its original publication.


  • That is the 3rd article I am reading here on onions and the problems with cutting onions. Get over it. Cutting onions is just 2/3 minutes of crying. Wear glasses if you need. There are far better things to write about such as the dedication of employees at Coles/Woolworths/Aldi or the courage of health workers. These are my two or three thoughts. Take care

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