Coffee & caffeine — Food safety facts
Do not feed · Dogs · full breakdown on the linked food page
Toxic. Caffeine overstimulates the heart and nervous system — vomiting, tremors, seizures and even death at high doses.
Short answer
Yes, coffee is toxic to dogs and this is an urgent situation. Caffeine can overstimulate the heart and nervous system, causing vomiting, tremors, seizures, and possibly death. Even a small amount like a teaspoon can be dangerous for a small dog. You need immediate veterinary care; call your vet or the ASPCA Animal Poison Control Center at 888‑426‑4435 right away.