The festive season is upon us and it is a time of year where indulgence is at the forefront of most families and friends. Rich foods and sweets are readily available and are all too tempting  for our furbabies and chocolate poisoning is a very common occurrence around Christmas.

Chocolate is derived from the roasted seeds of the plant Theobroma cacao, and the main toxic components are the methylxanthine alkaloids theobromine and caffeine. Humans can easily digest and excrete methylxanthines, the half life of theobromine being 2-3 hours. However absorption in dogs is slow, with metabolism in the liver and extrahepatic recirculation before excretion in the urine. The half life of theobromine in dogs is about 18 hours.

Theobromine primarily affects the central nervous system, cardiovascular system, and respiratory system, as well as having a diuretic effect. The first signs of poisoning in dogs include:

1. Vomiting
2. Haematemesis, and polydipsia.

Other signs may include; Hyperexcitability, Hyperirritability, Tachycardia, Excessive panting, Ataxia, and muscle twitching.

Effects may progress to cardiac arrhythmias, seizures, and death.

Most symptoms will begin to appear within two hours of ingestion, but, as theobromine is metabolised slowly, it can take as long as 24 hours for them to appear and up to three days for recovery

The lethal dose of theobromine is reported to be 100-500 mg/kg of body weight in dogs. However, not all types of chocolate contain the same amount of theobromine: cocoa powder and plain/dark chocolate contain the highest concentrations (20 mg/g and 15 mg/g), milk chocolate has much less (2 mg/g), and white chocolate has the lowest concentration (0.1 mg/g). Thus, less than 100 g of plain chocolate may be fatal for a 10 kg dog.

There is no specific antidote for theobromine; however, a combination of detoxification, supportive and symptomatic treatment can be successful. Detoxification includes emetics within the first 3-4 hours of ingestion, gastric lavage, activated charcoal administration, and oral cathartics.

Although it is relatively safe to give your pet a small chocolate treat occasionally, all dogs are potentially at risk from chocolate, and the safer alternative is to give special “pet chocolate” that does not contain theobromine (but can still cause obesity).