Onions are a staple ingredient in many of our favorite dishes, but did you know that they can be extremely toxic for dogs? Onion toxicity in dogs is a serious condition that can have potentially fatal consequences if left untreated. Dogs are particularly vulnerable to onion toxicity due to the thiosulphate content, which has been known to cause damage and anemia in their red blood cells. It is important for pet owners to be aware of the signs of onion poisoning in order to seek medical attention quickly if their dog has been exposed to onions. It is also essential that pet owners take steps to prevent their dogs from consuming onions in the first place as prevention is always better than cure.
What is onion toxicity in dogs and why does it matter?
Dogs can be poisoned by eating foods that contain Allium species like onions or garlic. This is called allium toxicosis, and it can result in hemolytic anemia and gastrointestinal effects.
All members of the Allium species can cause toxicosis in dogs if ingested, whether it be raw or cooked, dehydrated flakes or powder, and even medicinal supplements. The severity of symptoms varies per species and variety though due to the varying degree of toxic compounds present.
Organosulfur compounds such as N-propyl disulfide and thiosulfates in the gastrointestinal tract can disrupt the production of glutathione. This lack of protection leads to the denaturation of hemoglobin molecules, which form clumps called Heinz bodies. This results in the destruction of red blood cells both inside and outside of blood vessels, a process known as hemolysis.
Gastrointestinal effects are also a concern with Allium ingestion, although severity depends on preparation and species ingested.
The severity of gastrointestinal effects experienced after consuming Allium vegetables such as onions depends on the preparation and type of Allium ingested.
The toxicity of onion poisoning in dogs
The consumption of any variety of Allium spp., such as onions, shallots, and garlic, can lead to erythrocyte damage in cats and dogs. However, the clinical illness only occurs when the destruction of red blood cells surpasses the body's capacity to recover and repair itself. Hemolysis or red blood cell destruction occurs 3-5 days after ingesting onions or garlic in dogs.
Eating large amounts of onions or consuming small amounts over a long period of time will be toxic to dogs. The toxicity is related to the concentration and types of organosulfoxides in the plant. When plant tissues are damaged, enzymes release compounds called SCOs that give onions and garlic their taste and odor. The stronger the flavor or odour, the more toxic it is. Eating garlic supplements without strong odors or flavors is less likely to be toxic.
Onion toxicity in dogs is impervious to spoilage, cooking, and dehydration. Onion and garlic powders are much more toxic in small amounts than raw plant material due to their concentrated state.
What are the clinical signs of onion toxicity in dogs?
Onion toxicity in dogs may lead to gastrointestinal signs, such as vomiting, diarrhea, abdominal pain, loss of appetite, and depression. Dehydration is another potential consequence. Although some dogs may experience gastrointestinal upset, most do not show any clinical signs for a few days until there is significant red blood cell damage.
Within 1-7 days post-ingestion, other toxic symptoms may manifest, including tachypnea, dyspnea, weakness, icterus, and brown-colored urine. Additionally, pale mucous membranes may be present.
How is onion toxicity diagnosed in dogs?
In cases of onion toxicity, diagnosis is confirmed through a physical exam and laboratory tests. The initial test recommended for onion toxicity in dogs is a complete blood count (CBC) to detect the presence of Heinz bodies, which are irregularly shaped red blood cells. A Heinz body count is also necessary to determine the severity of onion toxicosis. Additionally, eccentrocytes, if noted in the CBC, are a major diagnostic feature of garlic-induced hemolysis.
Your veterinarian may also recommend other tests to assess organ function or damage caused by onion toxicoses, such as a biochemical profile, urinalysis, and abdominal radiographs or ultrasound which may reveal an enlarged liver and spleen.
What is the treatment for onion toxicity in dogs?
Sadly, there is no specific remedy for onion toxicity in dogs. If the dog displays any life-threatening symptoms, these must be handled immediately. Oxygen and/or a blood transfusion should be administered if necessary.
If a large amount of onion or garlic has been consumed within the last two hours, inducing vomiting may be necessary. Please contact your veterinarian for further instructions on how to induce vomiting. If ingestion has occurred longer than 2 hours, activated charcoal may be administered to help bind and eliminate onion toxins from the gastrointestinal tract.
By providing intravenous fluid therapy, it is possible to alleviate dehydration due to vomiting and/or diarrhea. In addition, this form of treatment can lessen the chance of hemoglobin-related renal tubular damage that occurs within the kidneys.
What is the prognosis for dogs with onion toxicity?
The success of treatment for onion toxicity in dogs is determined by the amount consumed, their current anemia levels, and how soon treatment begins after ingestion.
Can onion toxicity in dogs be prevented?
The best way to prevent onion toxicity in dogs is to avoid feeding them onion and garlic products. If you are using onion or garlic for cooking, make sure that any pieces of onion or garlic that your dog might find on the floor are properly disposed of. Additionally, it is important to make sure that your dog does not have access to onion and garlic products, such as onion powder or dried onion flakes.
Furthermore, some over-the-counter flea preventatives may contain Allium-based ingredients and these should be avoided.
Frequently asked questions
What is more toxic to dogs - garlic or onions?
For dogs, garlic has been clinically proven to be 3-5 times more potent than onions.
What is the toxic dose of onions in dogs?
Ingestion of 15-30 grams of onions per kilogram of body weight is enough to cause serious toxicity in dogs.
How toxic are cooked onions in dogs?
Cooked onion is still toxic to dogs, as the heat does not break down the compounds that cause onion toxicity. For this reason, the cooked onion should be avoided when feeding your dog.
In some cases, cooking can result in an increase in the toxic compounds found in Allium vegetables such as onions and garlic.
Onion toxicity in dogs is a serious condition that can have severe consequences. Symptoms of onion toxicity in dogs can be related to the gastrointestinal system or related to anemia, so seeking veterinary care is important if onion toxicity is suspected. Fortunately, onion toxicosis can be prevented by avoiding onion and garlic products, as well as over-the-counter flea preventatives containing Allium ingredients. If your dog has ingested onion or garlic, it's important to seek medical attention immediately for the best prognosis. By following these guidelines and being aware of the potential dangers posed by onion poisoning, you can help keep your canine companion safe from harm. If you have any further questions about onion toxicity in dogs, please consult with your veterinarian.