Are onions and garlic toxic to dogs?
Yes. Onion, garlic, leek and chives damage a dog's red blood cells, and the anaemia builds over several days rather than appearing at once. Raw, cooked, dried and powdered forms are all toxic, and garlic is three to five times stronger than onion. Pativo flags amounts from about 0.5% of body weight in onion, 25 g for a 5 kg dog. Call your vet today with the amount.
General information, not veterinary advice. If your pet may have eaten this, contact a vet now; do not wait for signs.
What to do right now
- Remove the food and work out what was eaten: fresh, cooked, dried or powder
- Estimate the amount and note your dog's weight
- Call your vet today with those details, even if your dog seems well
- Do not make your dog sick unless a vet on the phone tells you to
Go to an emergency clinic now if
- Your dog's gums look pale, white or yellow
- Your dog's urine is red, brown or dark
- Your dog is weak, tires very quickly or collapses
- Your dog is breathing fast or has a racing heart at rest
- Your dog ate a large amount, or onion or garlic powder, soup mix or supplements
Who to call
Your own vet first. If they are closed, the nearest emergency or out-of-hours clinic.
In the United States
Both answer 24 hours a day and may charge a consultation fee.
Signs to watch for
| Sign | Usually starts |
|---|---|
| Drooling, vomiting, diarrhoea, belly pain | Within a day |
| Lethargy, loss of appetite | 1-3 days |
| Pale or yellow gums | 3-5 days |
| Red or brown urine | 3-5 days |
| Fast breathing, racing heart, weakness | 3-5 days |
| Collapse | 3-5 days, severe cases |
Why are onions and garlic toxic to dogs?
Onions, garlic, leeks, chives and shallots belong to the Allium family. They contain sulphur compounds that damage the haemoglobin inside red blood cells. The damaged haemoglobin clumps into small lumps called Heinz bodies, and the body then destroys the affected cells, causing haemolytic anaemia: too few red blood cells to carry oxygen.
The Merck Veterinary Manual describes Heinz bodies forming within 24 hours, with the breakdown of red blood cells typically 3 to 5 days after the meal. This delay is why a dog can seem fine the next day and become weak and pale later in the week. Severe red cell breakdown can also strain the kidneys.
How much onion or garlic is dangerous for a dog?
Sources give different figures, and the difference is worth knowing. The Merck Veterinary Manual and a 2016 review in Frontiers in Veterinary Science report clinical signs after 15 to 30 g of raw onion per kg of body weight. Some veterinary references use a lower working threshold of 0.5% of body weight, which is 5 g per kg. Pativo uses this lower, more cautious figure.
| Dog weight | Onion at 0.5% of body weight (Pativo's threshold) | Onion at 15 g/kg (lower end reported by Merck) |
|---|---|---|
| 5 kg | 25 g | 75 g |
| 10 kg | 50 g | 150 g |
| 20 kg | 100 g | 300 g |
| 30 kg | 150 g | 450 g |
These figures are for fresh onion. Adjust for the form eaten:
- Garlic is three to five times more toxic than onion, so the same weight of garlic counts for much more.
- Dried and powdered forms are concentrated. VCA Animal Hospitals notes that one teaspoon of garlic powder equals about eight fresh cloves.
- Small amounts eaten every day, for example in table scraps, can add up over time.
Pativo's poison check does this calculation on the phone from your dog's weight and the amount.
What will the vet do?
If the meal was recent and your dog has no signs, the vet may make your dog vomit and may give activated charcoal, although Merck notes its effect on these compounds is unknown. There is no antidote.
The vet will then check a blood count, often repeating it over the following days to catch anaemia as it develops. Dogs with significant red cell damage may be admitted for intravenous fluids to protect the kidneys, oxygen if needed, and in severe cases a blood transfusion. Most dogs treated before severe anaemia recover as their bodies make new red blood cells.
How do I stop it happening again?
- Do not share leftovers, gravy, stuffing, pizza, curries or baby food made with onion or garlic.
- Keep onion and garlic powder, soup and stock mixes in a closed cupboard.
- Fence off vegetable beds with onions, leeks, garlic or chives.
- Avoid garlic-based supplements or treats unless your vet recommends them.
- If your dog has eaten some, keep up the daily log for a week and add a note on energy, appetite and gum colour, so changes are easy to report.
Cats are more sensitive than dogs: see onion and garlic in cats. For signs that need a clinic immediately, see emergency signs.
Questions owners ask
Is a little cooked onion in gravy or stuffing dangerous?
A small taste is unlikely to cause anaemia in a healthy adult dog, but cooking does not make onion safe, and powders and soup mixes are far more concentrated. Call your vet with the recipe and the amount eaten.
Is garlic safe for dogs in small amounts, as some supplements claim?
Garlic belongs to the same family and is three to five times more toxic than onion. Do not give garlic supplements or garlic-flavoured food unless your vet advises it.
Why does it take days to show?
The damage to red blood cells starts within a day, but the cells are destroyed gradually, and the Merck Veterinary Manual says anaemia typically appears 3 to 5 days after eating.
Sources
- Merck Veterinary Manual: Garlic and Onion (Allium spp) Toxicosis in Animals
- VCA Animal Hospitals: Onion, Garlic, Chive, and Leek Toxicity in Dogs
- Cortinovis and Caloni (2016), Household Food Items Toxic to Dogs and Cats, Frontiers in Veterinary Science
Checked against the sources listed on this page. How we write and check these pages