Onion Poisoning in Dogs – Watch Out What you Feed your Pekingese


Onion Poisoning in Dogs – Watch Out What you Feed your Pekingese

Giving your pet hamburger, spaghetti, pizza and other scraps from the table can only cause Heinz body hemolytic anemia. Majority of pet parents are aware of chocolate toxicity in dogs but have never heard of onion poisoning in dogs. You may say that you have given your pet gravy or a leftover pizza and nothing happened. A small amount wouldn’t really cause him any issues since onion toxicity is dose dependent. But onions in raw form (e.g. cooked, raw, dehydrated, or powdered) can cause a life-threatening form of hemolytic anemia to your beloved pet.

Onions contain a substance called Thiosulphate which dogs lack the enzyme in order to properly digest it. Thiosulphate causes the oxidation of hemoglobin in your dog’s red blood cells, which then form clumps thus weakening their cell membranes. The said clumps are called Heinz bodies which would protrude from the cell and causes rupture thus shortening the cell’s life span. And when a significant number of red cells are destroyed, anemia would then occur.

A massive decrease of red blood cells from your pet’s body would lead to lots of problems including heart failure. And the number of cells destroyed would depend on the amount of onion your pet has eaten. Small amounts of onion given over a long period of time can still cause the disease due to the gradual build up of Heinz bodies.

Onion Poisoning in Dogs

Onions are toxic to dogs. The toxicity is dose dependent, so the bigger the animal, the more onion need be consumed to cause a toxicity. Onion toxicity causes a Heinz body anemia. Heinz bodies are small bubble-like projections which protrude from a red blood cell and can be seen when the cells are stained. This “bubble” is a weak spot in the red blood cell and, therefore, the cell has a decreased life-span and ruptures prematurely.

If numerous red cells are affected and rupture, anemia can result. It is a form of hemolytic anemia. Onions are only one of the substances which can cause Heinz body anemia. Other substances such as Acetominophen (Tylenol) and benzocaine-containing topical preparations can also cause Heinz body anemia in the dog.

Source: JL Web, http://www.jlhweb.net/Boxermap/onions.html by Dr. Wendy Wallner, DVM

How to Deal with Onion Toxicity

In Large Doses:

  • Determine if your pet has taken a large dose of onion. If you have seen it yourself or you saw the remnants, call your vet immediately. Signs would include weakness, vomiting and blood in urine. Do not way for any of the signs to occur before taking action.
  • Induce vomiting once advised by the vet. If instructed, administer orally 1 tsp of hydrogen peroxide per 10 pounds of his weight. If you don’t have hydrogen peroxide isn’t available, substitute 1 tbsp. of dry mustard in 1 cup of water.
  • Rush your pet immediately to the vet as he may need other interventions necessary.

In Small Doses:

  • Call your vet to inform about the incident and ask for guidance.
  • Give him milk of magnesia as directed. If not available, give him dairy milk. This won’t treat but would slow the effect of the poison.
  • Keep an eye out for other signs and symptoms of the toxicity for the next days. If only a very small dose was eaten, symptoms won’t appear or would even disappear when onion has been discontinued from his diet.
  • Regardless of how small the onion intake is, bring him to the vet immediately to be checked thoroughly.

Professional guidance is critical to such events. So, if you suspect onion poisoning in dogs seek out your vet immediately. As a pet parent, you should also take the initiative to educate yourself on what foods that should and should not be given to your pet.

Do you feed your pet table scraps? Better think twice if you do.  Tell us more about your habits when it comes to your pet, we might be able to help you out.




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  1. Firstoff, the dogs came first. Their welllbeing and care come first. If the cat makes them nevuors, stressed, or uncomfortable, don’t get it.It’s completely unfair to the cat to keep it locked up in your room. This will probably just result in extreme shyness and unwillingness to adapt to new situations or people, should you have to move it or have it exposed to the rest of the house with time.Again, you know the answer.Let the kitten go to a different home.

  2. Does the same hold true for garlic? We used to give our large dog garlic to help with fleas.

    • Onions and garlic in all forms — powdered, raw, cooked, or dehydrated — can destroy a dog’s red blood cells, leading to anemia. That can happen even with the onion powder found in some baby food. An occasional small dose is probably OK. But just eating a large quantity once or eating smaller amounts regularly can cause poisoning. Symptoms of anemia include weakness, vomiting, little interest in food, dullness, and breathlessness.

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