Chocolate Toxicity

Pets are commonly exposed to chocolate, particularly around holidays such as Easter, Halloween, and Christmas.

Overview

Chocolate and cocoa products found in sweets, cakes, cookies, brownies, and baking ingredients are highly attractive to pets. They contain toxic compounds known as methylxanthines, such as theobromine and caffeine, which can cause severe illness. The amounts of these toxic compounds vary significantly between products, with dark chocolate, baking chocolate, and cocoa powder containing the highest concentrations.

Toxic Doses of Theobromine*

Mild Illness	20 mg/kg
Moderate to Serious	40 mg/kg
Lethal	100-200 mg/kg

*Pets can respond differently to chocolate doses and the type of chocolate ingested, with some dogs being more sensitive than others.

Levels of Theobromine

Cocoa contains 20-30 mg/g of theobromine

Baking chocolate or dark chocolate contains 6-16 mg/g of theobromine

Milk chocolate contains 2 mg/g of theobromine

White chocolate contains 0.1 mg/g of theobromine

Calculating the Chocolate Dose

You will need to know:

1. Your pet's weight (kgs)
2. The amount of chocolate ingested in grams or ounces
3. The estimated concentration of theobromine

To calculate the mg/kg dose of chocolate:

1. Multiply the amount of chocolate ingested (in grams) by the concentration of theobromine.
2. Divide this number by your pet's weight.

Examples

Milk Chocolate Toxicity 15 kg dog Ingests 85 g milk chocolate bar Milk chocolate concentration is 2 mg/g	85 x 2 = 170 mg 170/15 = 11.33 mg/kg You would expect a dose of < 20 mg/kg to cause only mild tummy upset in most dogs.
Dark Chocolate Toxicity 15 kg dog Ingests 85 g dark chocolate bar Dark chocolate concentration is approximately 16 mg/g	85 x 16 = 1,360 mg 1,360/15 = 90.66 mg/kg You would expect a dose above 40 mg/kg to cause serious illness in most dogs.

Estimated Doses of Chocolate Toxicity**

Size of Dog	Milk Chocolate	Dark or Baking Chocolate
Small Dogs	60-600 g	7-70 g
Medium Dogs	900 g-1.5 kg	100-200 g
Large Dogs	2 kg+	200-500 g

**The amount of theobromine and caffeine will differ between chocolate brands. Always contact your veterinary practice and inform them of the amount of chocolate ingested. They will be able to accurately calculate the dose that your pet has been exposed to.

Signs

Common signs of chocolate toxicity include:

• Twitching
• Vomiting
• Diarrhoea
• Panting
• Bloat
• Restlessness
• Tremors
• Seizures
• Heart arrhythmias
• Respiratory failure

Clinical signs usually occur within 6-12 hours of chocolate ingestion and can persist for up to 72 hours in severe cases.

The half-life of theobromine is approximately 17.5 hours, while caffeine has a half-life of about 4.5 hours, meaning it takes this amount of time for half of it to be excreted from the body.

Management

Your veterinarian will determine the amount of theobromine and caffeine ingested, so it is crucial to recall the type and amount of chocolate your pet has consumed. Chocolate ingestion can be a serious issue that requires urgent veterinary attention.

Treatment may include:

• Induced vomiting and removal of gastrointestinal contents
• Stabilisation and supportive care with fluids
• Medication for tremors or seizures

Depending on the level of toxic compounds ingested, most pets will make a full recovery with aggressive veterinary treatment.

Prevention

Tips to help prevent chocolate toxicity:

• Keep chocolate out of reach of pets.
• Look for dog treats made with carob (a chocolate alternative that contains no theobromine or caffeine).

References

Beasley, V.R., et al. (2023). A Systems Affected Approach to Veterinary Toxicology. University of Illinois College of Veterinary Medicine.

Drolet, R., et al. (2023). Cacao Bean Shell Poisoning in a Dog. Journal of the American Veterinary Medical Association.

Finlay, F. (2023). Chocolate Poisoning. British Medical Journal.

Hooser, S.B., Beasley, V.R. (2023). Methylxanthine Poisoning (Chocolate and Caffeine Toxicosis). In: Current Veterinary Therapy for Small Animal Practice, 10th ed. WB Saunders.