Why Is Onion Bad for Dogs? Everything You Need to Know

Is onion toxic for dogs?

Onion is toxic for dogs; it contains a substance called thiosulphate which is especially harmful to them. Thiosulphate is harmless to us, but in dogs (and also cats) it can cause hemolytic anemia, a condition in which red blood cells are destroyed faster than the body produces them. So no matter how you prepare it, dogs cannot eat onion under any circumstances.

Can dogs ever be given onion?

The answer is clear: dogs cannot be given onion, neither as a "treat" nor as part of their diet. Not raw, not cooked, not powdered. It is not an ingredient that we can make an exception for occasionally. In fact, the problem can worsen if consumed repeatedly, as the effects can accumulate and damage their blood system.

How much onion is bad for dogs?

When we talk about quantity, very little is enough for negative effects to start showing. For example, for a 10 kg dog, about 50 grams of onion can cause the first symptoms of toxicity. So, how much onion is bad for dogs depends on their weight, but even a small amount is dangerous.

What happens if a dog eats onion?

When a dog ingests onion, its body begins to react to the toxic compounds present in it, especially thiosulphate. This chemical directly affects the dog's red blood cells, which are responsible for transporting oxygen throughout the body. Onion causes a specific type of anemia known as hemolytic anemia.

Here we explain how the problem develops and what symptoms may appear in the dog.

Damage to red blood cells

The dog's red blood cells begin to be destroyed because thiosulphate affects their membrane, weakening it. This causes them to break down faster than the dog's body can produce new cells. Without enough red blood cells, the oxygen that should circulate throughout the body decreases, and the dog begins to show symptoms of oxygen deficiency, which severely impacts its health.

Common symptoms

The first symptoms are usually subtle, but they worsen over time. Here are some key signs to look out for:

Lethargy and weakness

The decrease in oxygen to organs and muscles causes extreme tiredness, lack of interest in play, and difficulties in carrying out daily activities. One way to motivate and stimulate them is to offer dog toys suitable for their size and energy.

Pale gums

This is a very characteristic sign of anemia. If you observe that your dog's gums are less pink than normal or have a whitish tone, it could be a sign of a lack of oxygen in the blood.

Vomiting and diarrhea

The dog may experience digestive problems after ingesting onion, as its system is trying to expel the toxic substance. This also causes dehydration and discomfort.

Rapid breathing or difficulty breathing

With the lack of red blood cells, the dog is forced to breathe faster to try to get more oxygen. In severe cases, it may appear panting or with labored breathing, which requires immediate veterinary attention.

Other side effects and severe cases

In cases of severe poisoning, the dog may experience collapse, tremors, and even seizures due to decreased oxygen in the brain. Additionally, if a very high amount of onion was consumed or the dog did not receive timely attention, it may suffer permanent damage to some organs due to prolonged oxygen deprivation.

The importance of veterinary care

If you suspect your dog has eaten onion, the safest thing to do is take them to the vet. Treatment may include intravenous fluids to prevent dehydration, medication to control symptoms, and in extreme cases, even blood transfusions to replenish damaged red blood cells.

How long does onion poisoning last in dogs?

The duration of poisoning depends on the amount ingested and the dog's size, but generally, symptoms can last from a few days to several weeks. Even with treatment, the dog's body needs time to recover and produce new red blood cells.

How to prevent a dog from eating onion?

It is essential to keep onion out of reach of dogs, whether in its natural form, powdered, or as part of a dish. Here are some basic tips to prevent your dog from accessing onion:

Keep onion out of reach

Store onion in safe places, either in the pantry or refrigerator, and make sure they don't have access to food scraps containing onion.

Avoid giving food scraps containing onion

Food scraps that we prepare for ourselves may contain onion, even in small quantities. Although it may seem like a good idea to share, it's best to avoid it.

Read labels on prepared foods

Some human foods contain onion powder, even if it's not visible. Make sure to check labels before offering any prepared food.

Educate your family

If you live with other people, it's important that everyone knows that onion is bad for dogs and that they should not offer food containing it. This includes visitors and friends who might want to give them "a treat" without knowing it.

Feed your dog a proper diet

The best thing you can do is ensure your dog receives a balanced and appropriate diet. This way you will avoid risks and ensure they get all the nutrients they need to be healthy and happy. Supplementing their diet with quality dog treats can be a good option, always in moderation.

Onion is, without a doubt, a food you should keep out of your dog's diet. It's easy to prevent something like this from affecting them, but you need to be aware of the risks and, above all, be informed. Remember that it doesn't matter if it's a small amount or if it's cooked: onion is toxic for dogs in all its forms.