Are onions safe or poisonous for dogs?

Can Dogs Eat Onions?

No, dogs should never eat onions as they are highly toxic and harmful to canines. 

Onions are part of the allium family which includes chives, spring onions and ornamental plants.  They contain a toxic principle known as N-propyl disulfide. This compound causes oxidative damage to your dog’s red blood cells by attaching to the oxygen molecules in those cells. This reduces the ability of the red blood cells to carry oxygen and also tricks your dog’s body into thinking that the blood cell is an invader. The red blood cell is destroyed in a process known as hemolysis, resulting in hemolytic anaemia. This can cause symptoms like weakness, vomiting, diarrhoea, lethargy, and even life-threatening consequences.

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What are the symptoms of dogs eating onions?

Dogs that have consumed onions can exhibit a range of symptoms, typically within a few days of ingestion. These symptoms can vary in severity depending on the amount of onion ingested.

  • Vomiting and Diarrhoea: Dogs may experience frequent vomiting and diarrhoea as their body reacts to the toxins present in onions.
  • Lethargy: Onions can lead to a decrease in energy levels and overall lethargy in dogs. They might appear unusually tired or unwilling to engage in their usual activities.
  • Weakness: One of the more pronounced effects of onion toxicity is weakness. Dogs might have trouble moving or even standing up.
  • Loss of Appetite: A decreased appetite or complete loss of interest in food is another common sign. Dogs may refuse to eat even their favourite treats.
  • Abdominal Pain: Dogs could display signs of discomfort or pain in the abdominal area. They might whine, whimper, or show signs of restlessness.
  • Rapid Heart Rate: An elevated heart rate (tachycardia) is another symptom of onion ingestion. You might notice your dog's heart beating faster than usual.
  • Pale Gums: Gums that are paler than usual or even slightly yellowish can indicate anaemia, which is a serious consequence of onion consumption.
  • Difficulty Breathing: In severe cases, onion toxicity can lead to breathing difficulties. Dogs might struggle to breathe properly, which requires immediate medical attention.
  • Dark Urine: Onions can lead to the destruction of red blood cells, which can result in a condition called hemoglobinuria. This can cause a dog's urine to become dark or discoloured.

Symptoms of onion poisoning in dogs can appear within a few hours to several days after ingestion, depending on the amount of onions consumed and the dog's individual sensitivity. 

symptoms of onion poisoning

Here's a general timeline of how quickly symptoms might manifest:

  • Within a Few Hours: In some cases, dogs may show initial signs of distress within a few hours of consuming onions. This could include vomiting or diarrhoea as their body tries to expel the toxins.
  • 12 to 24 Hours: More noticeable symptoms such as weakness, lethargy, and loss of appetite might become apparent within the first day after onion ingestion.
  • 24 to 72 Hours: As time progresses, symptoms can intensify. Dogs might experience more severe gastrointestinal distress, weakness, and possibly darkened urine due to the destruction of red blood cells.
  • 72 Hours Onward: In severe cases, dogs might continue to deteriorate over the next few days, with symptoms like rapid heart rate, difficulty breathing, and pale gums becoming more pronounced.

It's important to note that the timeline can vary depending on factors such as the dog's size, age, overall health, the amount of onion consumed, and the form in which the onions were ingested (cooked, raw, powdered, etc.). Additionally, some dogs may be more sensitive to onion toxicity than others.

If you suspect your dog has ingested any amount of onions, it's advisable to contact a veterinarian immediately, even if symptoms haven't appeared yet. Onion toxicity can be serious and potentially fatal, so early intervention is crucial for the best possible outcome.

timeline of onion poisoning in dogs

What amount of onion is toxic to dogs?

It only takes 100g of onion (about the size of a small onion) per 20kg of a dog’s weight to cause toxic effects. This means that a dog weighing approximately 20kg would only have to consume one medium-to-large onion to experience dangerous toxicity levels.

Can Dogs Safely Eat Cooked, Raw, or Powdered Onions?

No, dogs should not consume cooked, raw, or powdered onions. Onions, in all forms, contain compounds that are toxic to dogs and can lead to serious health issues.

Cooked Onions: Cooking onions does not eliminate the toxic compounds responsible for their harmful effects on dogs. Even though the potency of these compounds might be slightly reduced, cooked onions are still unsafe for dogs and can lead to the same adverse health reactions.

Raw Onions: Raw onions are particularly potent in their toxicity. They contain a higher concentration of the compounds responsible for damaging a dog's red blood cells and causing hemolytic anaemia. Even a small amount of raw onion can be harmful to dogs.

Powdered Onions: Onion powder, often found in various processed foods, is concentrated and can contain a significant amount of the toxic compounds. Due to its concentrated nature, even a small quantity of onion powder can be highly toxic to dogs.

The level of toxicity can vary based on factors such as the dog's size, breed, and individual sensitivity. It's important to understand that there is no safe threshold for onion consumption in dogs. Even small amounts can potentially lead to severe health complications.

What to do if your dog eats onion?

If you suspect that your dog has consumed onions, it's crucial to take immediate action to ensure their safety and well-being. Onions can be toxic to dogs and can lead to serious health issues.

  • Contact Your Veterinarian: Call your veterinarian. Provide them with information about the situation, including the amount of onions your dog may have ingested, the form of onions (cooked, raw, powdered), and your dog's size and breed.
  • Observe Symptoms: Keep a close watch on your dog for any signs of onion toxicity, such as vomiting, diarrhoea, lethargy, weakness, rapid heart rate, difficulty breathing, pale gums, or darkened urine.
  • Do Not Induce Vomiting: Do not attempt to induce vomiting in your dog unless specifically instructed to do so by a veterinarian. In some cases, inducing vomiting can worsen the situation, especially if the onions have been consumed within the past hour.

If onion toxicity is treated promptly and effectively, the prognosis for a dog's recovery is generally positive. Early intervention can significantly increase the chances of a successful outcome.

treatment of onion poisoning in dogs

What Are Alternative Safe Natural Treats for Dogs?

There are many natural, safe alternative treats for dogs to enjoy without any harmful effects. Natural treats and chews should be free from artifical flavourings and additives.


Fishcakes are a delicious, natural biscuit treat for dogs packed with healthy Omega Oils whilst providing a satisfying crunch.  They are naturally grain and gluten free.

Just Meat Sticks

Just Meat Sticks are available in a range of different proteins for your dog to enjoy. They are moist and tasty, easy to break into different pieces and perfect for a post walk snack.

With Wags and Woofs,

Laura, Dolly & Reggie

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