Chocolate and dogs: how much is toxic?

The short answer: Dark and baking chocolate are severely toxic; milk chocolate is moderately toxic; white chocolate is essentially safe

Chocolate toxicity in dogs comes from theobromine and, to a lesser extent, caffeine. Both are methylxanthines metabolized slowly by dogs — theobromine has a half-life of about 17.5 hours in dogs vs 2–3 hours in humans. Dogs cannot clear it efficiently, and toxic effects stack with repeated exposure.

Toxic doses (theobromine per kg body weight)

• >20 mg/kg: mild GI signs (vomiting, diarrhea, restlessness)
• >40 mg/kg: cardiac signs (rapid heart rate, arrhythmia)
• >60 mg/kg: seizures, tremors, severe cardiac toxicity
• >100 mg/kg: potentially fatal

Theobromine content by chocolate type

| Chocolate type | Theobromine (mg per oz / 28g) | |---|---| | White chocolate | 1 mg | | Milk chocolate | 60 mg | | Dark chocolate | 150 mg | | Semisweet baking chocolate | 170 mg | | Unsweetened baking chocolate | 400 mg | | Cocoa powder | 800 mg | | Dry cocoa beans | 600 mg |

How much dangerous per dog weight

Milk chocolate:

• 5 kg dog: 50 g (~2 oz) for mild signs, 200 g for severe
• 15 kg dog: 150 g for mild signs, 600 g for severe
• 25 kg dog: 250 g for mild signs, 1 kg for severe

Dark chocolate — about 2.5× more toxic per gram than milk.

Baking chocolate / cocoa powder — 7–13× more toxic than milk chocolate. A single 30 g (1 oz) square of unsweetened baking chocolate can cause severe toxicity in a medium-sized dog.

Signs of chocolate toxicity

Onset 6–12 hours after ingestion: