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Onions - Why you must never feed them to a dog.

Onions - Why you must never feed them to a dog.

Onions - Why you must never feed them to a dog.

Onions are a food staple found in almost every kitchen. Even though humans may enjoy the taste of onions, they can be extremely toxic to dogs and should not be given to dogs ever.

Why are Onions toxic to dogs?

Onion are part of the Allium family along with Shallots, Spring onions, Leeks, Chives and Garlic (Garlic is the exception to the rule and despite what many will argue actually has some healthy properties to dogs and only become toxic in huge quantities -We will do a blog about this another time!!)

Onions contain a compound called N-propyl disulfide which is toxic for pets and can cause gastrointestinal issues, anemia, and even death.

It is harmless for humans, but in Dogs it can break down the red blood cells. This lead to Anemia as a dogs immune system turns on itself thinking the red blood cells are baddies and attacks to destroy them. Red blood cells are essential to transport Oxygen around the body.

 Onion toxicity levels

Onion toxicity can occur any time after your dog has started digesting the onions … to a few days after eating onions.

Small amounts of onion can be harmful - as little as 0.5% of your dogs weight. As a guide – 100g of onion per 20 kg of a dogs weight can be toxic. So a 20 kg dogs – similar size to Kenzo would only need to eat on medium size onion to be at risk of dangerous toxicity levels.  

 Scarily Skye stole a ¼ of a home made quiche from the worktop which had Spring onions in it- I got advice from a Vet and luckily the amount she had consumed was minimal but I was on edge for days – checking her constantly for any side effects. It would have been a very different story if she had eaten the whole thing.

What are the signs of Onion Toxicity ?

Common signs of onion toxicity in dogs include

  • vomiting,
  • diarrhea,
  • decreased appetite,
  • Pale Gums,
  • increased thirst,
  • abdominal pain,
  • dark urine,
  • Fast heart rate,
  • lethargy,
  • passing out,
  • Troubled movement or balance,

 Signs of Anemia

Checking the colour of your Dogs gums are a good indicator of Anemia – They should be a healthy pink colour. Signs of Anemia may not show for a few days which is why quick and immediate action is needed. Symptoms of Anemia show a severe Toxic reaction and include –

  • Whitish or pale gums
  • Skin bruising
  • Dark / Bloody Poo
  • Blood in vomit
  • Fatigue

Anemia can be fatal and treatments include IV fluids and blood transfusions if detected soon enough.

 How to keep Dogs safe from Onions

It is in our control what our dogs eat and do not feed them anything that contains onions including dehydrated or onion powder as an ingredient, which is often found in Baby food or soups. If you are giving your dogs food scraps or home cooked food - always consider if any onion has been used.

Additionally, you can keep onions out of your Dog's reach by storing them in a secure place or even in the refrigerator.

If you grow anything from the Onion family in the garden be certain your Dog will not help themselves and dig them up to eat. Same consideration if you throw Onion scraps onto a compost heap they may have access too.

 Alliums are not the only food or plant that can be harmful to your dog. There are numerous common plants that may be toxic to your pup such as lilies, tulips, daffodils and azaleas. (Again – for more discussion another time!)


What should you do if your Dog eats Onions?

 Should you Dog somehow get there little cheeky paws on something with onions in and eat it… You need to seek advice quickly. Once Onions have been digested – the damage has been done.

Your vet may suggest providing activated charcoal or other medications to help reduce further absorption and toxicity. They may also consider inducing Vomitting. You can buy activated charcoal in a dog-specific product and it is useful for lots of emergencies, so worth keeping some in your first aid kit. 

 It is also important to keep a close eye on your Dog for any signs of illness such as vomiting, diarrhea, and abdominal pain as described above.


By following these tips, you can help keep your pup safe and healthy. If you have any questions or concerns, it is always best to consult with your veterinarian.