Chocolate — Food safety facts
Do not feed · Dogs · full breakdown on the linked food page
Toxic. Theobromine and caffeine cause vomiting, tremors, seizures and heart problems. Dark and baking chocolate are worst.
Short answer
Yes, call your vet or the ASPCA Animal Poison Control Center at 888-426-4435 right away. Chocolate is toxic to dogs because it contains theobromine and caffeine, which can cause vomiting, tremors, and heart problems. The danger is highest with dark or baking chocolate, but any chocolate ingestion should be treated as an emergency. Do not wait for symptoms to appear, as they can be delayed and become severe.