Can dogs have serrano peppers?
No – serrano pepper is not toxic, but it can irritate your dog’s digestive system.
Why it is or is not safe
Spicy peppers contain capsaicin, which can cause stomach irritation in dogs.
Serving guidance
Do not offer intentionally. If your dog eats a small amount, monitor for vomiting or diarrhea.
Symptoms to watch for
Drooling, vomiting, diarrhea, abdominal discomfort.
Sources: See full veterinary references here