Chocolate Toxicosis (Methylxanthine Toxicosis) in Dogs

Summary

Chocolate toxicosis results when dogs ingest dangerous amounts of chocolate. Methylxanthines like theobromine and caffeine are toxic to dogs, and both are present in chocolate.  Symptoms like vomiting and diarrhea appear within 2 - 12 hours following ingestion of a toxic dose. Higher doses lead to hyperactivity and seizures. High doses cause lethal cardiovascular and nervous system damage.

Treatment depends on the amount ingested and how much time elapsed after consumption. Early treatment focuses on removing the chocolate from the stomach before serious complications develop. There is no antidote, so clinical signs like heart arrhythmias and seizures are treated symptomatically. 

When a dog ingests a dangerous amount of chocolate, the efficacy of early treatment in effort to remove the chocolate is the major determining factor in the outcome.

Risk Factors

Chocolate ingestion by dogs is very common because dogs tend to eat any food within reach, but ingestion of a toxic dose is less common. Concentrated forms of chocolate like baker’s chocolate and dark chocolate are more concentrated sources of methylxanthines, so these are toxic in lower quantities. 

Chocolate that is diluted out into baked goods is much less risky, because the volume of the entire foodstuff the dog would have to eat to be exposed to a dangerous amount of chocolate is large. White chocolate contains a negligible amount of theobromine and is not a cause of chocolate toxicosis.  

Chocolate toxicosis is potentially lethal, so it’s important for pet parents to use online chocolate toxicity calculators with perfect accuracy. Information from a veterinary professional or pet poison hotline is a better option. Time is of the essence when treating chocolate toxicosis, so immediate access to veterinary care is the best plan for a good outcome.  Prognosis is largely dependent on the amount and strength of chocolate consumed and the dog’s size and health status.

Possible Causes

Chocolate toxicosis is caused by ingestion of a toxic dose of theobromine, a compound commonly found in chocolate.  Ingestion of all methylxanthines–such as caffeine– can produce symptoms similar to chocolate toxicosis. Chocolate also contains caffeine, but theobromine is present in significantly higher amounts.

Main Symptoms

The main symptoms of chocolate toxicosis include:

• Vomiting • Diarrhea • Polyuria(frequent urination) • Restlessness • Tremors

• Polydipsia (excessive water drinking) • Hyperactivity• Ataxia (poor muscle control, difficulty walking)

• Seizures

Detailed Characterization

The severity of the symptoms varies in accordance with the dose ingested and the symptoms occur in sequence. A general rule is one ounce (28 grams) of milk chocolate per pound of body weight is a potentially lethal dose. 

The amount of theobromine is sufficient to cause heart arrhythmias once the dose of milk chocolate exceeds more than 0.24 ounces per pound of body weight (15 grams per kg). Doses in excess of 0.35 ounces of milk chocolate per pound of body weight (22 grams per kg) are likely to produce seizures and tremors.   

A large amount of ingested chocolate has the potential to form a firm ball (bezoar) in the stomach. This complicates treatment by interfering with decontamination and prolonging absorption of the toxins.

Testing and Diagnosis

Primary diagnosis is based on history of chocolate ingestion and presence of chocolate in the vomit.  A methylxanthine assay is available to confirm diagnosis. A dog with symptoms of chocolate toxicosis will likely undergo additional bloodwork and heart monitoring (ECG)

Steps to Recovery

Treatment is more likely to be successful when initiated as quickly as possible after ingestion, before any symptoms develop. Early treatment prioritizes removing as much chocolate as possible from the dog’s digestive tract. 

Induced vomiting is helpful within the first 2 hours following ingestion. Gastric lavage is another option for larger ingestions. There is no safe way to induce vomiting at home. Induction of vomiting is best performed in clinic by a veterinarian.

Once as much chocolate as possible is removed from the digestive tract, activated charcoal is given to prevent the absorption of toxins. IV fluids and laxatives speed up the rate in which theobromine is expelled from the body. 

Symptoms such as tachycardia and seizures are treated with medications while the dog is recovering. Hospitalization is required for monitoring and nursing care until symptoms subside fully. In severe cases, symptoms remain for up to 72 hours. In milder cases, time and severity of symptoms vary based on the individual animal and amount ingested. If the chocolate is removed before being digested, symptoms are relatively mild and subside within 12-36 hours.

Prevention

Chocolate toxicosis is not contagious. It is prevented by keeping sources of chocolate out of reach from dogs.

Is Chocolate Toxicosis Common in Dogs?

Chocolate toxicosis is one of the most common causes of poisoning in dogs, due to its abundant availability and appeal.

Typical Treatment

• Decontamination: ◦ Inducing vomiting and gastric lavage to remove chocolate

◦ Activated charcoal to prevent absorption of the toxin ◦ Laxatives to speed passage of the chocolate

◦ IV fluid diuresis to hasten elimination of the toxin

• Supportive and nursing care to keep the dog clean, dry, and comfortable

• Symptomatic care:  ◦ Antiarrhythmics ◦ Anti-seizure medications