What Are the Dangers of Onions to Dogs?
Onions (Allium cepa) in any form are toxic to dogs—they destroy red blood cells, causing anemia. A small amount of onion can cause problems, although it can be several days before the dog exhibits symptoms. The smaller the dog, the smaller the amount of onion needed to have an adverse effect on your pet. Even very small amounts can build up over time, and the accumulation will eventually cause damage to the red blood cells. Anemia Anemia occurs when the hemoglobin level in red blood cells falls to a low level. Hemoglobin is responsible for delivering oxygen to cells and organ tissue and is essential for good health. Onions contain a substance called thiosulphate that dogs are unable to digest. Thiosulphate causes hemoglobin to oxidize and form into clumps (called Heinz-bodies). These clumps break down the red blood cell membrane structure and, ultimately, the cells die. As the red blood cell count lowers, a dog develops anemia. With a low level of red blood cells, the amount of hemog
