How Much Onion Will Hurt A Cat. Answered by anita runolfsson on sun, may 16, 2021 4:16 am. The toxicity of onions in cats is caused by the hypersensitivity of the cat’s red blood cells to the oxidant present in fresh or dried onions.
Will one piece of onion hurt my cat? Onions, like others in its family, can damage a cat’s red blood cells. Onion toxicity in cats is a hypersensitive reaction of the feline’s red blood cells to the oxidant present in fresh or dried onions.