Canis ISSN: 2398-2942

Theobromine / chocolate poisoning

Synonym(s): Methylxanthine

Contributor(s): Lisa Moore, Nicola Bates

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.
Print off the owner factsheet on Chocolate toxicosis Chocolate toxicosis to give to your client.

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.
  • Bates N, Rawson-Harris P, Edwards N (2015) Common questions in veterinary toxicology. JSAP 5​6 (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.

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