Leek Poisoning in Cats

Members of the Allium family, leeks are potentially deadly to cats. Most poisonings result from animals eating something from this family that were grown in the family garden or inside the home. The cat can also ingest leeks from prepared foods that it samples. As your cat chews the leek, organosulfoxides in the plant convert into several sulfur compounds. This leads to the breakdown of your cat’s red blood cells. It only needs to eat a small amount (5g of onion per kg of body weight) for the toxins to affect its blood cells.

Leeks are one member of the Allium family, along with garlic, onions and chives. While we can easily eat and tolerate the foods in this group, our pets, including our cats, cannot. Poisoning by garlic and onion leads to oxidative damage to your cat’s red blood cells, which could lead to their rupture. Unfortunately, your cat won’t show symptoms right away. Instead, the onset of symptoms is delayed, making it much more difficult for you to figure out what your cat could have eaten to make it so sick. The distinctive smell of onions or garlic in your cat’s vomit or feces is one distinctive sign of what is making your cat ill. It’s deal if you actually see your cat nibbling at leeks so you can get the cat and a small sample of the plant to your vet’s office before the cat gets noticeably ill.

Keeping in mind that a few days may pass between your cat eating leeks and developing symptoms, this is what you’ll see:

• Excessive drooling
• Oral irritation
• Lack of appetite
• Abdominal pain
• Nausea
• Vomiting
• Strong smell of onion on cat’s breath and in its urine and feces
• Diarrhea
• Lethargy
• Discolored urine (reddish or brown)
• Loss of muscle coordination
• Depression
• Jaundice

Symptoms related to the breakdown of red blood cells include:

• Elevated heart and respiratory rate
• Hemolytic anemia
• Heinz body anemia
• Weakness/fatigue
• Shortness of breath
• Pale gums
• Panting
• Exercise intolerance
• Blood in cat’s urine
• Collapse
• Death related to anemia

Leeks contain N-propyl disulfide; this substance is what can makes your cat so sick. It works by causing oxidative or burning damage to your cat’s hemoglobin within its red blood cells. As this happens, your cat's blood cells are increasingly unable to transport oxygen from its lungs throughout its body. This leads to oxygen starvation (hemolytic anemia). 

Tell your vet that your cat ate leeks when you take it in for diagnosis and treatment. 

Your vet will give your cat a full physical, which should include both a urinalysis and blood work. He will rule out other illnesses and poisonings, such as from brassicaceous vegetables (bok choy, green leaf vegetables, cauliflower, broccoli, cabbage, garden cress, brussels sprouts), acetaminophen, propylene glycol, vitamin K, benzocaine, dl-methionine, copper, naphthalene, and zinc. Common illnesses he will rule out include diabetes mellitus (when connected to ketoacidosis, hyperthyroidism, hepatic lipidosis (fatty liver), lymphoma or other neoplasms.

After your vet has narrowed down your cat’s illness to leek poisoning, he will rehydrate it through intravenous support and a bowl of water. He will also continuously monitor the cat to make sure it isn’t developing signs of anemia.

Your cat will receive activated charcoal, which helps to absorb the toxins specific to leeks, removing them from your cat’s system. If it is vomiting excessively or is experiencing low blood pressure or hemoglobinuria (excreting free hemoglobin in its urine), the vet may provide intravenous medications.

He may also administer vitamin C (ascorbic acid) to your cat. This helps reduce the levels of methemoglobin, which is the oxidized form of hemoglobin. Methemoglobin doesn’t easily or readily adjoin itself to oxygen, which contributes to your cat’s worsening condition. Your vet may need to give two doses to your cat so its blood plasma levels return to normal.

Your cat may need supplemental oxygen therapy until its blood cells are repaired enough to carry oxygen to all parts of its body.

Your cat’s diet may also be changed to a food lower in potential oxidants. 

As long as you get your cat veterinary treatment soon after it ate leeks, it has a good chance of recovery. Beginning treatment before its red blood cells begin to break down helps it to avoid developing anemia. 

Because of the potential lag time between ingestion of leeks and the first symptoms, the risk of anemia for your cat are high. If you only suspect that your cat may have eaten a leek, get veterinary care.

Once your cat returns home, make sure it can’t get to onions, garlic, chives or leeks while you are chopping or cooking them. Even though these are so poisonous for them, cats are still drawn to their scent and, out of natural curiosity, may nibble enough to become seriously ill.