If a dog eats onions, it can lead to onion poisoning, which is toxic and potentially life-threatening. Onions contain a compound called N-propyl disulfide, which causes oxidative damage to the dog's red blood cells. This damage leads to the destruction of red blood cells, a process called hemolysis, resulting in hemolytic anemia-a condition where the blood cannot carry enough oxygen

Symptoms of Onion Poisoning in Dogs

• Vomiting and diarrhea
• Abdominal pain and reduced appetite
• Lethargy and weakness
• Pale gums and jaundice (yellowing of skin and eyes)
• Rapid breathing and increased heart rate
• Brown-colored urine and dehydration
• In severe cases, collapse and seizures may occur

Symptoms may appear within 24 hours but often take a few days to manifest, especially the anemia-related signs, which usually develop 1-5 days after ingestion

Toxic Dose

The toxic dose is roughly 15 grams of onion per kilogram of the dog's body weight, about half a cup for a 45-lb dog. Onion powder is even more concentrated and toxic in smaller amounts

What to Do If Your Dog Eats Onions

• Contact a veterinarian immediately.
• Do not induce vomiting at home; a vet can safely induce vomiting and administer activated charcoal to absorb toxins.
• The dog may require intravenous fluids, blood tests to monitor anemia, and possibly a blood transfusion in severe cases.
• Hospitalization for observation and supportive care may be necessary

Additional Notes

• All forms of onions (raw, cooked, powdered) are toxic.
• Other allium family plants like garlic, leeks, and chives are also toxic.
• Some dogs are more sensitive than others.
• Onions can be hidden in pre-made foods, so always check ingredients

In summary, onion ingestion in dogs causes oxidative damage to red blood cells leading to anemia and gastrointestinal upset, with potentially serious health consequences requiring prompt veterinary intervention.