d-limonene

Limonene is a terpene found in citrus peel. Cats' livers lack sufficient glucuronyl transferase, so they metabolize these compounds far less efficiently than people or dogs. The ASPCA Animal Poison Control Center lists citrus oils and d-limonene products among the essential oils most toxic to cats; signs include drooling, tremors, wobbliness, depression, and low body temperature. The main risk comes from concentrated oils and insecticidal or cleaning products, but it is still best to avoid foods listing "citrus extract" or "natural flavor" from citrus.

Other common names: limonene, citrus oil extract, citrus extract, orange oil, lemon oil, grapefruit seed extract, citrus peel extract, 檸檬烯, 柑橘精油, 柑橘萃取, 葡萄柚籽萃取, d-リモネン