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Onion, Garlic, Chive, and Leek Toxicity in Dogs

By Renee Schmid, DVM & Ahna Brutlag, DVM, MS, DABT, DABVT Pet Poison Helpline; Lynn Buzhardt, DVM

Emergency Situations, Pet Services

What a tantalizing aroma…onions, garlic, chives, and leeks sizzling in a pan. This combination of kitchen herbs is the basis of many culinary masterpieces. While these traditional seasonings delight our taste buds, they can make our pets very sick. Here is what dog owners and amateur chefs should know about this fearsome foursome.

What are these species of herbs?

All four species of herbs belong to the Allium family and have been kitchen staples for ages. This is quite a large family of plants with approximately 95 species of cultivated or native leeks, chives, garlic, onions, shallots, and scallions in North America, not counting ornamental varieties. These plants form bulbs that nestle underground and are very aromatic. Green above-ground shoots are edible as well but emit a less intense odor.

The domesticated species commonly implicated in canine toxicity are Allium cepa (onion), Allium porrum (leek), Allium sativum (garlic), and Allium schoenoprasum (chive), with garlic being the most toxic.

Any form of these vegetables and herbs can cause poisoning. Dried, powdered, liquid, cooked or raw herbs are all poisonous to your dog. Dried and powdered ingredients, including dried minced onions and garlic powder, contain a higher concentration of substance on a per weight basis due to the water content being removed. For example, 1 teaspoon of garlic powder is equivalent to 8 cloves of fresh garlic. Thus, this type of exposure can result in a higher risk of poisoning. Human nutritional supplements may also be a source of these toxic plants.

What do they do?

Besides making your dinner taste great, onions, garlic, leeks and chives can cause serious medical problems for your dog. Although clinical signs of illness, such as vomiting, can occur soon after your dog eats any of these, the full onset of signs may take several days to appear.

 In most cases, consumption causes gastroenteritis or inflammation of the gastrointestinal tract. Irritation of the mouth, drooling, nausea, abdominal pain, vomiting and diarrhea may occur.

The potentially deadly part of Allium spp. damages red blood cell membranes. This makes the red blood cell fragile and causes them to burst. Red blood cells are needed to carry oxygen throughout the body. When these cells are destroyed, important organs do not get enough oxygen. A low red blood cell count (anemia) results in increased heart rate, elevated respiratory rate and effort, weakness, discolored urine, kidney damage, collapse and even death. Certain breeds, especially dogs of Japanese descent (Akita, Shiba Inu), may have a higher risk for toxicity.

How do they do it?

These simple plants have a complicated mechanism of action. These plants contain oxidizing agents that cause oxidative hemolysis of the red blood cells. As the concentration of oxidants in the red blood cells exceeds the ability of antioxidant metabolic pathways to “de-toxify” the cell, poisoning occurs. The red blood cell membranes become fragile due to direct oxidative damage and burst.

What are the signs of illness?

Signs of poisoning vary depending upon the amount eaten. Gastrointestinal upset commonly occurs, including signs of decreased appetite, vomiting, diarrhea, depression, abdominal pain, and drooling. Eating larger amounts may cause red blood cell damage resulting in weakness, elevated heart rate, increased respiratory rate and effort, panting, pale gums, or red-colored urine. Kidney damage can occur in dogs that have red blood cell destruction. Increased drinking, increased or decreased urination, vomiting and decreased appetite are common signs of kidney damage.

How is poisoning diagnosed?

Most cases are diagnosed in pets that have the expected signs along with changes in the red blood cells and a known or suspected ingestion. Bloodwork to evaluate red blood cell counts are performed to support the diagnosis. Bloodwork to assess kidney function and a urinalysis may also be recommended.

How is poisoning treated?

Early decontamination and treatment decrease the risk for serious effects. If ingestion occurred within a few hours of treatment, the veterinarian may induce vomiting. Once vomiting is controlled, activated charcoal may be administered. This can decrease absorption of the toxins from the gastrointestinal tract. Activated charcoal should only be administered by a veterinarian. Otherwise, aspiration into the lungs and life-threatening changes in sodium levels may occur. Blood work to look at the red blood cells will also be performed. Since destruction of the cells may not show up for several days, repeated blood work is typically recommended for up to a week. If you believe your pet ingested ibuprofen, it is important to call your veterinarian or Pet Poison Helpline, a 24/7 animal poison control center, at 1-800-213-6680 right away to have the risk of poisoning assessed.

If red blood cell destruction occurs, hospitalized care may be recommended. Fluids are often administered intravenously. Pets that develop a low red blood cell count (anemia) may require oxygen supplementation or a blood transfusion. Repeat bloodwork to monitor the red blood cell count and kidney values is often needed for days to weeks in these pets.

How can poisoning be prevented?

Preventing access to plants, herbs, seasonings and supplements is key to avoid poisoning. Never give food seasoned with onions or garlic to your dog. Fence off gardens and plant beds containing onions, garlic, chives, or leeks. Dispose of leftovers containing these ingredients in an area where pets do not have access. Remember, some pets will even open lower cabinets or get into open drawers. Keep in mind that pets can get on counters or knock items off counters and tables.

Never give medications or supplements to a pet without first consulting a veterinarian. Do not leave any vitamins and supplements where unattended pets may reach them. It is not uncommon for pets to chew through closed bottles. Curious pets may want to check out purses, back packs, lunch boxes or suitcases. These items should not be left in areas where pets can get into them. Do not assume a pet will avoid eating something just because it has a bad taste. If medications/plants/seasonings are dropped, confine all pets in another area of the home until all the material can be picked up.

Whenever a toxic exposure is suspected, immediate action is recommended. Early consultation and treatment are often less expensive and can help prevent serious health effects.

Pet Poison Helpline, an animal poison control center based out of Minneapolis, MN is available 24/7 for pet owners and veterinary professionals that require assistance treating a potentially poisoned pet. The staff provides treatment advice for poisoning cases of all species, including dogs, cats, birds, small mammals, large animals and exotic species. As the most cost-effective option for animal poison control care, Pet Poison Helpline’s fee of $65 per incident includes follow-up consultations for the duration of the poison case. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can be found online at www.petpoisonhelpline.com

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