Onions are highly toxic to dogs and cats.
Fortunately, most cats have better sense than to eat onions, but onions that have been cooked with a tasty sauce may be attractive to both species. Grocery store onions are not the only culprit. Wild onions growing as volunteers in your yard are just as poisonous. Even rotten onions thrown out in the compost pile retain their toxic capabilities. Dietary supplements, cooking products (such as seasonings and flavorings) as well as juice have the potential for causing poisoning.
The dangerous poison results in anemia in its victim. “Heinz body” formation occurs, “tagging” the red blood cell for destruction by the immune system or even outright breakdown of cells because of increased fragility. If a sufficient number of red blood cells (RBCs) is destroyed, the result is too few red cells to carry sufficient oxygen for normal body function. Several days may pass between the ingestion of onions and onset of clinical signs.
One-half of one percent (0.5%) of a pet’s body weight in ingested onions is sufficient to cause toxicity. That equates to just 2.5 ounces of onion in a 30-pound dog. Cats and Japanese dog breeds (Shiba Inu, Akita) tend to have an even greater sensitivity to onion poisoning because of an inherited, non-fatal defect in red blood cell formation.
A pet concurrently on certain medications is placed at even greater risk for illness. These include, but are not limited to acetaminophen and sulfur-based antibiotics. Acetaminophen (the active ingredient in Tylenol) should never be administered to pets under any circumstances.
Treatment is aimed at removing the offending material. Your veterinarian will induce vomiting. He may also administer one or more treatments with activated charcoal. If anemia has reached dangerous levels, he may also begin a blood transfusion with type-matched blood. No specific antidote is available.
The toxic ingredient is in the organosulphoxide family. Think carbon molecules combined with sulfur. The combination makes a strong oxidizer, which results in damage to hemoglobin molecules in red blood cells.
See you Monday, Dr. Randolph.