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.

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

Treatment

Prevention

Outcomes