Same allium family as onion and garlic — avoid entirely.
Toxic. Chive plants in the garden are a real risk for grazing cats.
Allium toxins damage red blood cells.
ASPCA Animal Poison Control: (888) 426-4435 · Pet Poison Helpline: (855) 764-7661 — 24/7, a fee may apply. Your own vet first when reachable.