What happens if a dog ingests chocolate?

Chocolate Ingestion in Dogs: Immediate Veterinary Assessment Required

If a dog eats chocolate, immediate veterinary intervention is critical because chocolate contains theobromine and caffeine—methylxanthine alkaloids that are potentially lethal to dogs due to their prolonged 18-hour half-life in canines, compared to just 2-3 hours in humans. 1

Mechanism of Toxicity

Theobromine accumulates in dogs because they metabolize it extremely slowly, undergoing hepatic metabolism with extrahepatic recirculation before urinary excretion. 1 This prolonged exposure affects multiple organ systems:

• Central nervous system: Hyperexcitability, hyperirritability, tremors, seizures 1
• Cardiovascular system: Sinus tachycardia, cardiac arrhythmias 1
• Respiratory system: Tachypnea, excessive panting 1
• Renal system: Diuretic effects leading to polyuria/polydipsia 1

Clinical Presentation Timeline

Symptoms typically begin within 2 hours of ingestion but may be delayed up to 24 hours, with recovery potentially taking up to 3 days due to slow theobromine metabolism. 1

Early Signs (First 2-6 Hours)

• Vomiting and haematemesis 1
• Polydipsia 1
• Agitation and restlessness 2

Progressive Signs

• Tremors and muscle twitching 1
• Hyperthermia 2
• Ataxia 1
• Cardiac arrhythmias 1
• Seizures and potential death 1

Risk Assessment by Chocolate Type

The lethal dose of theobromine is 100-500 mg/kg body weight, but toxicity varies dramatically by chocolate type. 1

Theobromine Concentration by Type:

• Cocoa powder: 20 mg/g (highest risk) 1
• Dark/plain chocolate: 15 mg/g 1
• Milk chocolate: 2 mg/g 1
• White chocolate: 0.1 mg/g (minimal risk) 1

Critical calculation: Less than 100 grams of dark chocolate can be fatal for a 10 kg dog. 1 In a recent case series, 28 of 44 symptomatic dogs had ingested dark or bitter chocolate. 2

Laboratory Findings

When clinical pathology is performed, expect: 2

• Hyperlactataemia (most common metabolic derangement)
• Hypokalaemia (from excessive urinary losses)
• Mild hyperglycaemia (stress response)
• Elevated ALT and AST (hepatic involvement)

Immediate Management Protocol

There is no specific antidote for theobromine toxicity—treatment is entirely supportive. 1

Decontamination (if within 2-4 hours of ingestion):

• Induce vomiting with apomorphine 2
• Administer activated charcoal to prevent further absorption 1

Supportive Care:

• Intravenous fluid therapy for hydration and forced diuresis 1
• Esmolol for tachycardia and cardiac arrhythmias 2
• Sedatives (benzodiazepines) for tremors and seizures 2
• Oxygen supplementation as needed 1
• Temperature management for hyperthermia 2

Prognosis

With prompt decontamination and aggressive supportive care, prognosis is excellent—mortality rate is less than 3%. 2 In a recent series of 156 chocolate ingestion cases, 43 of 44 symptomatic dogs survived with appropriate treatment. 2

However, 112 of 156 dogs (72%) remained asymptomatic, emphasizing that not all chocolate ingestions result in clinical toxicity. 2 The outcome depends critically on:

• Type of chocolate ingested (dark > milk > white) 1
• Amount consumed relative to body weight 1
• Time elapsed before treatment 1

Critical Pitfalls to Avoid

Do not wait for symptoms to develop before seeking veterinary care—the 18-hour half-life means theobromine continues accumulating even after ingestion stops. 1

Cocoa shell mulch in gardens poses an equal threat (25 mg/g theobromine concentration) and may attract dogs due to its chocolate aroma. 1

Never assume small amounts are safe—even "occasional small treats" carry risk, and pet-specific chocolate substitutes without theobromine should be used instead. 1