canis - Articles
Theobromine / chocolate poisoning
Synonym(s): Methylxanthine
Introduction
- Toxic signs caused by theobromine (a methylxanthine).
- Signs: gastrointestinal, CNS and cardiovascular signs.
- Diagnosis: History, clinical signs.
- Treatment: activated charcoal orally, supportive therapy.
- Prognosis: good in most cases but guarded in dogs with seizures or arrhythmias.
Presenting signs
- Animal found near chocolate wrappers, chocolate debris.
- Vomiting.
- Diarrhea.
- Excitability.
- Chocolately odor to the breath.
Acute presentation
- Tachycardia.
- Sudden death (cardiovascular collapse) - rare.
Geographic incidence
- Theobromine toxicity can occur anywhere chocolate is consumed.
Cost considerations
- Yes.
Special risks
- Smaller breeds where quantity consumed relative to bodyweight may be greater.
- Dogs with pre-existing cardiac disease and/or on theophylline medication.
- Dogs with CYP1A2 1117C>T polymorphism may be more at risk of toxicity due to reduced metabolism. This polymorphism is not breed-related.
Pathogenesis
Etiology
- Theobromine is a methylxanthine occurring as the major alkaloid in chocolate and cocoa powder. Chocolate is made from the fermented, dried then roasted beans of Theobroma cacao.
- Chocolate also contains a small amount of caffeine (also a methylxanthine).
- The type of chocolate is defined by the quantity (percentage) of cocoa solids the chocolate contains.
- Cocoa mulch used in gardening is also a potential source of theobromine.
- Some laxatives (usually senna-based) contain theobromine.
Pathophysiology
- Toxic effects in dogs occur at theobromine doses of 20 mg/kg, with severe signs at 40-50 mg/kg and seizures at 60 mg/kg.
- Deaths have occured after ingestion of 80-300 mg of theobromine/kg body weight.
- The amount of theobromine in products will vary due to natural differences in cocoa beans and the formulation of the products.
- Milk chocolate contains 1.0-2.1 mg theobromine/g.
- Dark or plain chocolate contains around 0.4-8.8 mg theobromine/g.
- White chocolate and cocoa butter contain a negligible quantity of theobromine.
- Cocoa powder can contain 4.6-38 mg theobromine/g.
- Cocoa mulch can contain 10-30 mg/g.
- Rapidly absorbed from small intestine.
- Excreted in urine.
- Theobromine inhibits phosphodiesterase, thereby increasing cAMP concentrations and causing catecholamine release.
- Antagonize adenosine receptors and inhibit phosphodiesterase → stimulate myocardial and skeletal muscle contraction.
Timecourse
- Generally within 2-4 hours, sometimes 6-12 hours
- Recovery can occur within 24 hours but can be 48-72 hours.
- Sudden death (cardiovascular collapse) may occur - rare.
Epidemiology
- Cases of chocolate ingestion in dogs are common when chocolate and chocolate products are readily available in the home, eg Christmas, Valentine's Day and Easter.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Weingart C, Hartmann A, Kohn B (2021) Chocolate ingestion in dogs: 156 events (2015–2019). JSAP doi.org/10.1111/jsap.13329.
- Bates N, Rawson-Harris P, Edwards N (2015) Common questions in veterinary toxicology. JSAP 56 (5), 298-306 PubMed.
- Agudelo C F, Filipejova Z, Schanilec P (2013) Chocolate ingestion-induced non-cardiogenic pulmonary oedema in a puppy: a case report. Vet Med 58 (2), 109-112 VetMedResource.
- European Food Safety Authority (EFSA) (2008) Theobromine as undesirable substances in animal feed - Scientific Opinion of the Panel on Contaminants in the Food Chain. European Food Safety Authority Journal 6 (9), 725 EFSA.
- Gwaltney-Brant S (2001) Chocolate intoxication. Vet Med 96 (2), 108-111 VetMedResource.
- Stidworthy M F, Bleakley J S, Cheeseman M T, Kelly D F (1997) Chocolate poisoning in dogs. Vet Rec 141 (1), 28 PubMed.
- Drolet R, Arendt T D, Stowe C M (1984) Cacao bean shell poisoning in a dog. JAVMA 185 (8), 902-908 PubMed.
- Glauberg A & Blumenthal H P (1983) Chocolate poisoning in the dog. JAAHA 19 (2), 246-8 VetMedResource.
- Gans J H, Korson R, Cater M R, Ackerly C C (1980) Effects of short-term and long-term theobromine administration to male dogs. Toxicol Appl Pharmacol 53 (3), 481-96 PubMed.
Other sources of information
- Dolder L K (2013) Methylxanthines: caffeine, theobromine and theophylline. In: Small animal Toxicology, 3rd edition. Peterson M E, Talcott P A (eds). St Louis, Missouri: Elsevier.
Organisation(s)
- ASPCA Animal Poison Control Center: www.aspca.org/pet-care/animal-poison-control, telephone number (888) 426-4435
- Veterinary Poisons Information Service (VPIS): www.vpisglobal.com. + 44 (0) 2073 055 055