Chocolate intended for human consumption contains the chemical theobromine which can be fatal for dogs. It is found in greater quantities in rich, dark expensive chocolate. As little as 250g can kill a small dog.
One gramme of dark chocolate - or cocoa powder or dark cooking chocolate - contains 13.7mg of theobromine compared to 1.5mg in milk chocolate.
Theobromine belongs to the same group of chemicals, known as the methylxanthines, as caffeine.
It passes into the bloodstream rapidly, speeding up the heartbeat and causing fast breathing and strong muscular contractions, which may progress into convulsions. Increased urine output causes increased drinking which leads to vomiting.
"The clinical picture is one of great distress and death can occur as a result of cardiac and respiratory arrest," said Alison Hudd, a veterinary nurse writing in the Veterinary Nursing Journal.
The LD50 (lethal dose which will kill 50 per cent of a group of subjects) for dogs is 250-500mg of theobromine, equivalent to a dog eating between 19g and 38g of chocolate per kilogramme of its weight. The lowest dose of theobromine which has been recorded as causing death in a dog is 110mg/kg. There is no known antidote.
Vet Roger Green advises owners: "If you think your dog has consumed any quantity of chocolate take it to the vet straight away.
"If you can make it sick with a crystal of washing soda down the throat so much the better, but still bring it to the vet as soon as you possibly can."Reuse content