Dog Ate Onion or Garlic? Onion Toxicity Calculator
Check what your dog ate, from a slice of onion to sage and onion stuffing and gravy, against their weight
Last updated: 29 October 2026
Dogs cannot eat onions or garlic, raw or cooked. They damage red blood cells and can cause anaemia. Problems are consistently seen when a dog eats more than 0.5% of its body weight in onion: 5 g per kg.
For a 10 kg dog that is about 50 g of onion, under half a medium onion. Garlic and dried onion are stronger, so smaller amounts count. Signs often take 3–5 days to appear. Use the calculator, see the table of UK foods, and call your vet if you are unsure.
Do Not Wait for Symptoms
Anaemia can take days to develop, and early treatment is easier. If you are worried, call your vet or Animal PoisonLine on 01202 509 000 (24 hours, charged). Do not try to make your dog sick at home. This calculator is a guide only and is not a substitute for veterinary advice.
Check What Your Dog Ate
Cooking does not make onion safe. Counts as about 1 g of raw onion per gram.
How Much Onion Is Toxic to Dogs? Chart by Weight
Amounts eaten in one go at which to call your vet (5 g of onion per kg), with the level at which poisoning signs are reported (15 g per kg) underneath.
| Dog’s weight | Onion | Garlic cloves | Onion powder |
|---|---|---|---|
| 2.5 kg (6 lb) | 13 gsigns: 38 g | 0.8signs: 2.5 | 0.6 tspsigns: 1.8 tsp |
| 5 kg (11 lb) | 25 gsigns: 75 g | 1.7signs: 5 | 1.2 tspsigns: 3.6 tsp |
| 10 kg (22 lb) | 50 gsigns: 150 g | 3.3signs: 10 | 2.4 tspsigns: 7.2 tsp |
| 15 kg (33 lb) | 75 gsigns: 225 g | 5signs: 15 | 3.6 tspsigns: 10.8 tsp |
| 20 kg (44 lb) | 100 gsigns: 300 g | 6.7signs: 20 | 4.8 tspsigns: 14.4 tsp |
| 30 kg (66 lb) | 150 gsigns: 450 g | 10signs: 30 | 7.2 tspsigns: 21.6 tsp |
| 40 kg (88 lb) | 200 gsigns: 600 g | 13.3signs: 40 | 9.6 tspsigns: 28.7 tsp |
A medium onion is about 110 g and a garlic clove about 3 g. Garlic is treated as 5 times stronger than onion, and onion powder as about 8.7 times stronger than fresh onion. Repeated small amounts over several days add up, and some dogs react to less.
Stuffing, Gravy and Other UK Foods: How Much Is Too Much?
How big a dog one portion could put over the “call your vet” level (5 g per kg) and the level where signs are reported (15 g per kg), worked out from UK supermarket labels.
| One portion | Call your vet for dogs up to | Signs possible in dogs up to |
|---|---|---|
| Onion, medium (about 110 g)about 110 g of raw onion | 22 kg | 7.3 kg |
| Garlic clove (about 3 g)about 15 g of raw onion | 3 kg | 1 kg |
| Onion powder or granules (teaspoon)about 20.9 g of raw onion | 4.2 kg | 1.4 kg |
| Garlic powder (teaspoon)about 120 g of raw onion | 24 kg | 8 kg |
| Stuffing ball made from Paxo sage & onion mixabout 18.5 g of raw onion | 3.7 kg | 1.2 kg |
| Aunt Bessie's sage & onion stuffing ball (26 g)about 6.5 g of raw onion | 1.3 kg | under 1 kg |
| Onion gravy from granules (50 ml)about 1.9 g of raw onion | under 1 kg | under 1 kg |
| Onion bhaji (45 g)about 39.6 g of raw onion | 7.9 kg | 2.6 kg |
| Garlic bread (quarter of a baguette, 48 g)about 8.4 g of raw onion | 1.7 kg | under 1 kg |
Labels checked October 2026. Recipes vary, and many ready meals, sausages, crisps and sauces contain onion or garlic powder without stating how much, so treat these as a rough guide. Homemade stuffing and gravy made with fresh onions can contain far more.
Christmas Dinner and Dogs
Stuffing and gravy are the main onion risks on the plate, but they are not the only ones. Christmas pudding, mince pies and fruit cake contain raisins (see the grape and raisin calculator), and chocolate is everywhere (see the chocolate calculator).
Cooked bones can splinter, and fatty leftovers such as turkey skin and pigs in blankets can trigger an upset stomach or pancreatitis. Plain, unseasoned turkey meat with no skin or bones is the safest treat.
Why Are Onions and Garlic Toxic to Dogs?
Onions, garlic, leeks, shallots and chives belong to the allium family. They contain compounds that damage a dog’s red blood cells, which the body then destroys faster than it can replace them, leading to anaemia. Cooking, drying and powdering do not remove these compounds, and dried forms are more concentrated. Akitas, Shiba Inus and Jindos are reported to be more sensitive.
Frequently Asked Questions
Can dogs eat onions?
No. Onions, garlic, leeks, shallots and chives can damage a dog’s red blood cells and cause anaemia. Raw, cooked, dried and powdered onion are all harmful, and cooking does not make them safe. That includes foods made with onion, such as stuffing, gravy and onion bhajis.
How much onion is toxic to dogs?
Problems have been seen consistently when a dog eats more than 0.5% of its body weight in onion at once, which is 5 g per kg, or 50 g for a 10 kg dog. The MSD Veterinary Manual reports clinical signs at 15 to 30 g per kg. Dried onion and onion powder are much more concentrated, and repeated small amounts can add up.
Is garlic worse than onion for dogs?
The MSD Veterinary Manual says garlic is 3 to 5 times more toxic than onion, although sources differ and no exact garlic dose is agreed. This calculator treats garlic as 5 times stronger to stay on the safe side. Garlic powder is the most concentrated of all.
Can dogs eat stuffing?
It is best not to. Sage and onion stuffing is made with onion, and stuffing made from a dried mix contains dried onion, which is more concentrated. A few balls from a packet mix can reach the level where vets want to know for a small dog. Use the calculator to check what your dog ate.
Can dogs have gravy?
Gravy is not a good idea. Many gravies contain onion or garlic powder, and gravy is very salty and fatty. A small lick of gravy made from granules contains little onion, but onion gravy and homemade gravy with onions contain more, so check what your dog had.
How long after eating onion will a dog get sick?
A dog may be sick or have an upset stomach within a day, but the damage to red blood cells usually shows 3 to 5 days later. Watch for pale gums, weakness, tiredness, fast breathing and red or brown urine, and call your vet even if your dog seems fine at first.
My dog ate onion. What should I do?
Call your vet or Animal PoisonLine on 01202 509 000 with your dog’s weight and what they ate. Do not make your dog sick at home. If it was recent, your vet may make your dog sick and give activated charcoal, then check their blood over the next few days.