Why chocolate is toxic to dogs
Chocolate contains theobromine and, to a lesser extent, caffeine. Both are methylxanthines, stimulants that people metabolise within a few hours but that a dog takes up to three days to clear. Meanwhile, theobromine speeds up the heart, stimulates the nervous system, relaxes smooth muscle and increases urine production.
The dose is what defines the danger, and it depends on three things: the dog's weight, the amount of chocolate and, above all, the type. The more cocoa a product has, the more theobromine it concentrates. That is why 30 grams of cocoa powder are a serious problem for a 10 kg dog, while the same amount of milk chocolate usually stays in the "monitor" zone. White chocolate has barely any theobromine, but its fat and sugar can cause vomiting, diarrhoea or pancreatitis.
The veterinary community uses guideline thresholds: from around 20 mg/kg digestive signs and restlessness appear; from 40 mg/kg cardiac effects may appear; from 60 mg/kg there is a risk of seizures; and the median lethal dose (LD50) sits around 100 to 200 mg/kg. This calculator applies those same thresholds to the data you enter.
Theobromine by type of chocolate
Average values used by the calculator. Brands vary, so if you have the wrapper at hand check the cocoa percentage and pick the closest category.
| Type of chocolate | Theobromine (mg per g) | In a 30 g serving |
|---|---|---|
| White chocolate | 0.25 mg/g | 7.5 mg |
| Milk chocolate | 2.4 mg/g | 72 mg |
| Semisweet or dark chocolate (45–60%) | 5.5 mg/g | 165 mg |
| Dark chocolate (70–85%) | 8 mg/g | 240 mg |
| Unsweetened baking chocolate | 14 mg/g | 420 mg |
| Cocoa powder | 26 mg/g | 780 mg |
Toxic dose by dog's weight
Grams of chocolate needed to reach 20 mg/kg (symptoms likely) and 60 mg/kg (emergency) by weight. These are quick references; use the calculator for your exact case.
| Type of chocolate | Reaches 20 mg/kg with… | Reaches 60 mg/kg with… |
|---|---|---|
| White chocolate | 400 g | 1,200 g |
| Milk chocolate | 42 g | 125 g |
| Semisweet or dark chocolate (45–60%) | 18 g | 55 g |
| Dark chocolate (70–85%) | 13 g | 38 g |
| Unsweetened baking chocolate | 7.1 g | 21 g |
| Cocoa powder | 3.8 g | 12 g |
| Type of chocolate | Reaches 20 mg/kg with… | Reaches 60 mg/kg with… |
|---|---|---|
| White chocolate | 800 g | 2,400 g |
| Milk chocolate | 83 g | 250 g |
| Semisweet or dark chocolate (45–60%) | 36 g | 109 g |
| Dark chocolate (70–85%) | 25 g | 75 g |
| Unsweetened baking chocolate | 14 g | 43 g |
| Cocoa powder | 7.7 g | 23 g |
| Type of chocolate | Reaches 20 mg/kg with… | Reaches 60 mg/kg with… |
|---|---|---|
| White chocolate | 1,600 g | 4,800 g |
| Milk chocolate | 167 g | 500 g |
| Semisweet or dark chocolate (45–60%) | 73 g | 218 g |
| Dark chocolate (70–85%) | 50 g | 150 g |
| Unsweetened baking chocolate | 29 g | 86 g |
| Cocoa powder | 15 g | 46 g |
| Type of chocolate | Reaches 20 mg/kg with… | Reaches 60 mg/kg with… |
|---|---|---|
| White chocolate | 2,400 g | 7,200 g |
| Milk chocolate | 250 g | 750 g |
| Semisweet or dark chocolate (45–60%) | 109 g | 327 g |
| Dark chocolate (70–85%) | 75 g | 225 g |
| Unsweetened baking chocolate | 43 g | 129 g |
| Cocoa powder | 23 g | 69 g |
Example: a 100 g milk chocolate bar provides about 240 mg of theobromine. For a 5 kg dog that is 48 mg/kg (high risk); for a 30 kg dog it is 8 mg/kg (low risk, monitor).
Symptoms of chocolate poisoning in dogs
They usually appear 6 to 12 hours after eating the chocolate, although with high doses they can start earlier. They range from mild to severe depending on the theobromine per kilo.
First signs (digestive)
Vomiting, diarrhoea, drooling, strong thirst and heavy urination. Chocolate or wrapper remains are often seen in the vomit.
Nervous stimulation
Restlessness, hyperactivity, panting, muscle tremors and inability to settle. The dog seems "wired".
Cardiac effects
Very fast or irregular heartbeat, laboured breathing, high temperature. They appear from 40 mg/kg and need immediate veterinary care.
Severe picture
Rigidity, seizures, collapse and loss of consciousness. This is an emergency: every minute counts.
What to do if your dog ate chocolate
Follow these steps in order. The most important thing is to act quickly and with clear information.
Remove the chocolate and gather the facts
Move the dog away from the remaining chocolate and keep the wrapper. Note the type (cocoa percentage), how much of the pack is missing and what time it happened. Weigh the dog if you don't know its current weight.
Calculate the dose and call the vet
Use the calculator to estimate the mg/kg and call your vet or an emergency clinic with that information. If it was eaten less than 2 hours ago, they will likely recommend inducing vomiting at the clinic. Do not induce it at home without professional instruction.
Go in or monitor depending on the risk level
With high risk or emergency, go to the clinic now: treatment (activated charcoal, fluids, heart-rate control and anticonvulsants) works best the earlier it starts. With low risk, keep the dog calm, with water available and under observation for 24 hours.
Frequently asked questions
References
- Merck Veterinary Manual: Chocolate toxicosis in animals.
- ASPCA Animal Poison Control Center: Chocolate toxicity in dogs.
- Gwaltney-Brant S. Chocolate intoxication. Veterinary Medicine, 2001.
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