It’s that time of year: the chocolate challenge that runs from the holidays through Valentine’s Day. The risk to us is calorie overload, but for our pets it’s much more sinister.

Dogs are more vulnerable than cats because they have more chocolate cravings. Either way, chocolate ingestion can be fatal. That’s because theobromine — the stimulant found in chocolate — has a much more potent effect on our pets than it does on us. The same goes for caffeine. The combo can overstimulate an animal’s heart and nervous system, causing signs ranging from excess urination and vomiting to seizures. Even if the chocolate content is low, the fat and sugar in many goodies can cause painful indigestion in pets.

So, when it comes to celebrating the holidays with chocolate treats, keep them far away from your four-legged friends.