Toothpaste, along with sugar free gum and mints, often contains a sweetening ingredient called xylitol that’s been found to be extremely toxic to both dogs and cats.
It's become so iconic that attempts to change its taste in 1985 — sweetening it in a move projected to boost sales — proved disastrous, with widespread anger from consumers.
At first, its bitter taste made it suitable as a medicine for ailments, like upset stomachs, but sweetening it with honey, sugar, or vanilla quickly made chocolate a popular delicacy in the Spanish court.