Onions?

Why it’s unsafe

Onions belong to the Allium family, along with garlic, leeks and chives. Pet Poison Helpline explains that when onions and garlic are eaten in large or chronic amounts, they cause Heinz body formation in red blood cells and anemia, and the anemia causes the main clinical signs.

The Merck Veterinary Manual notes that dogs and cats have been affected by raw, cooked, dehydrated and granulated onions. It reports that cats are the most susceptible species, followed by dogs, and that poisoning is most often linked to concentrated forms such as dehydrated flakes, powders or dry onion soup mixes. Pet Poison Helpline also warns against using onion or garlic powder chronically in pet food.

Onion powder is hidden in many soups, sauces, gravies, seasoning blends and some baby foods, so check labels.

Signs often take days to show. Merck says hemolysis typically occurs 3 to 5 days after exposure, because the anemia develops gradually.

What to give instead

Do not feed onions in any form. Before sharing leftovers, check that the dish has no onion, onion powder or other Allium ingredients, and be wary of gravy, stuffing, soups and pre-seasoned meat.

For a crunchy, low-calorie treat, offer plain carrots or cucumbers instead, keeping treats to no more than 10% of daily calories.

If your dog already ate it

If your dog has eaten onion, note how much, what form (raw, cooked, powder) and when, and your dog's weight. Then call your vet, an emergency clinic, or ASPCA Animal Poison Control (888) 426-4435 / Pet Poison Helpline (855) 764-7661 (US; fees may apply). Outside the US, call your local emergency vet.

Do not try to make your dog vomit at home; leave that decision to a vet. Your vet may advise monitoring or bloodwork over the following days.

Watch for tiredness, weakness, pale or yellowish gums, fast breathing or heart rate, reduced appetite, vomiting, diarrhea or dark urine. Clinical signs usually appear a few days after exposure.