Chocolate toxicosis in animals may result in potentially life-threatening cardiac arrhythmias and central nervous system (CNS) dysfunction. Chocolate poisoning occurs most commonly in dogs, although many species are susceptible. Dogs are most often affected because of their indiscriminate eating habits and easy access to sources of chocolate.

Aetiology of Chocolate Toxicosis in Animals

The primary toxic principles in chocolate are the methylxanthines – theobromine  and caffeine. Both constituents contribute to chocolate toxicosis. The exact amount of methylxanthines in chocolate varies with the type of chocolate.

Below is a table showing the methylxanthine content of various types of chocolate:

As you can see from the above table the darker (or more “pure”) the chocolate is the more dangerous it is if consumed by animals. In other words, the less blocks of chocolate they need to eat before becoming sick. With white chocolate actually being a negligible source of chocolate toxicity.

Symptoms of Chocolate Toxicosis

Clinical signs of chocolate toxicosis usually occur within 6–12 hours after ingestion. Initial clinical signs may include excessive water drinking, vomiting, diarrhoea, abdominal distention, and restlessness.

Signs may progress to hyperactivity, excessive urination, fast heart rate, panting or fast breathing rate, uncoordinated (drunken) movements, rigidity, tremors, and seizures.

Sadly, in severe cases coma and death can occur.

Toxic Doses

Individual animals may vary in their susceptibility to methylxanthines but in general, mild clinical signs (vomiting, diarrhoea, excessive water drinking) may occur in dogs ingesting 20 mg/kg; cardiotoxic effects occur after ingesting 40–50 mg/kg, and seizures occur after ingesting doses ≥ 60 mg/kg.

For practical examples this translates to:

So, as you can see from the above tables if your 40kg Rottweiler steals 3 blocks of your Top Deck chocolate at teatime there is no need to even worry about it, they’ll be just fine. But if your 2kg teacup Yorkie breaks into your grocery cupboard and devours the whole slab of Lindt 90% dark chocolate you should seek emergency veterinary care immediately.

Diagnosis of Chocolate Toxicosis

• Clinical signs
• History of exposure

Treatment of Chocolate Toxicosis in Animals

• Emesis induction in patients that remain clinically normal
• Management of potentially life-threatening clinical signs
• Supportive care

In patients that remain clinically normal, induction of emesis should be considered with recent exposures (eg, within 2 hours of chocolate ingestion). Activated charcoal can also be dosed orally to bind the toxins and prevent them from being absorbed from the gut.

Stabilizing patients with clinical signs is a priority in treating chocolate toxicosis. There is unfortunately no specific antidote or cure for chocolate toxicosis and so treatment is supportive and symptomatic and would include:

• Intravenous fluids to help flush methylxanthines through the kidneys and out of the body in the urine and to correct electrolyte imbalances.
• Anti-emetics to control vomiting.
• Anti-epileptics to control seizures.
• Anti-arrhythmic drugs to help control cardiac arrythmias.

Clinical signs may persist for up to 72 hours in severe cases.