Chocolate toxicity in dogs is driven by methylxanthines — primarily theobromine (3,7-dimethylxanthine) and caffeine. The toxic principles come from *Theobroma cacao*. The table below gives methylxanthine concentration by product (verbatim from source):
| Product | Methylxanthine |
|---|---|
| dry cocoa powder | 28.5 mg/g |
| unsweetened (baker's) chocolate | 16 mg/g |
| milk chocolate | 2.3 mg/g |
White chocolate is "an insignificant source of methylxanthines."
Clinical effect doses (theobromine, dogs)
- "(vomiting, diarrhoea, polydipsia) may be seen in dogs ingesting 20 mg/kg" of theobromine.
- "cardiotoxic effects may be seen at 40–50 mg/kg, and seizures may occur at doses ≥60 mg/kg."
- "approximately 1.3 g/kg b.wt. of baker's chocolate is sufficient to cause symptoms of toxicity" (baker's chocolate ≈16 mg/g theobromine → ~80 mg/kg theobromine).
- "A 10-kilogram dog can be seriously affected if it eats a quarter of a 250 g packet of cocoa powder or half of a 250 g block of cooking chocolate."
Dose guidance scales with theobromine content: a dog needs to eat >250 g of milk chocolate to be affected, but far less cocoa powder / baker's chocolate.
Source: pdf-raw/pmc-pet-food-toxic-pmc2984110.txt — first-hand peer-reviewed review "Some food toxic for pets" (PMC2984110, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2984110/), Tavily server-side extract 2026-07-21.