Why is Garlic bad for pets?

Garlic is sort of the miracle vegetable proven to have various medicinal values in humans, but the opposite goes for dogs and cats alike. Just like onions, garlic is toxic to dogs and cats, but since garlic is more concentrated, so is the toxicity level. A small amount of garlic clove can cause toxicosis in small dogs and cats. If ingested in certain amounts, it can result to death.

When Garlic is ingested by pets, it causes hemolytic anemia, Heinz body anemia, and methemoglobinemia which cause damage to their red blood cell. These types of anemia can essentially cause the red blood cells to become weak and burst due to the disulfides and thiosulphates compounds found in garlic. Toxicity may vary depending on your pet's weight, breed, and clinical history. Always contact your vet for medical advise.

What are the symptoms of Garlic Toxicity?

Please note that it may take several days after ingestion for the symptoms to appear. When symptoms do occur, this may include vomiting and diarrhea coupled with symptoms of anemia which can be “breathlessness, lethargy, pale, yellow, or “muddy” colored gums, rapid breathing, and an elevated heart rate”. When this occurs, your pet could also develop discolored urine along with abdominal pains. It may take several days to weeks for symptoms of anemia to appear.  Source.