Onion Poisoning (Allium Toxicosis) in Dogs

Onions and other plants in the allium family contain oxidizing compounds that damage red blood cells. If the dog’s red blood cell regeneration cannot keep up with the damage, anemia results.

Professional advice from a pet poison hotline or veterinary professional is helpful for determining the risks associated with onion ingestion. All forms - fresh, dried, and powdered - are toxic with powders being the most concentrated, garlic being the most toxic (3-5 times more toxic than onions), and chives and leeks the least toxic. The toxic dose of fresh onions in healthy dogs is anything over 15 grams per kilogram of body weight.

While ingestion of any amount of onion (and other Allium species) causes red blood cell damage, healthy dogs have an abundance of red cells and are always making more. The prognosis depends on the amount consumed and the extent of resulting red blood cell damage.

Timely intervention immediately after ingestion makes a big difference in the prognosis and is the best way to avoid serious health effects. Onion toxicosis is potentially lethal if enough is consumed to cause a life-threatening degree of red blood cell damage.

Onion poisoning results when a dog consumes a toxic dose of garlic, onions, chives, or leeks, either all at once, or after small ingestions over time.

Sometimes onion toxicosis also leads to kidney damage.

Dogs presenting for treatment within four hours of ingestion of a potentially dangerous dose of onion, etc., undergo induction of vomiting or gastric lavage to remove as much onion from the digestive system as possible.

Note: induction of vomiting and administration of activated charcoal should only be performed by a veterinarian. There is no safe way to induce vomiting at home.

Dogs with no known ingestion presenting with symptoms of anemia undergo routine diagnostic testing such as physical examination, bloodwork, and urinalysis.

There is no antidote for onion toxicosis, so baseline bloodwork and repeated monitoring are useful for dogs presenting too late for decontamination.

Treatment for severe anemia includes IV fluid administration, supplemental oxygen, and blood transfusions.

Prognosis is dependent on the size of the ingested dose, the efficacy of decontamination efforts, and the severity of the resulting anemia.

To reduce the possibility of onion toxicosis do not allow access to onions, garlic, chives, or leeks. Strategies include:

• Cleaning up promptly if these plants are dropped on the floor while cooking; keeping dogs out of the kitchen while preparing food
• Fencing any garden beds containing these plants
• Ensuring any indoor plants, garlic braids, or other means of growing or storing these plants are well out of reach of pets
• Not sharing people food; storing leftover people food in sealed containers away from pets

Ingestion of Allium spp. plants is common in dogs, but ingestion of enough to cause life-threatening anemia is not. Eating small portions of foods seasoned with these plants does not usually pose a significant risk to healthy, larger dogs.

• Induction of vomiting
• Gastric lavage
• Activated charcoal
• Intravenous fluids
• Supplemental oxygen
• Blood transfusion