Chocolate is digested much more slowly by dogs than people. Therefore symptoms may not appear for many hours after the chocolate is eaten.
Do not be fooled by this into thinking that everything is okay. The earlier chocolate poisoning is treated the more likely you are to save the dog’s life.
In addition, the very slow deactivation of theobromine by dogs means that the effects of chocolate poisoning can be very prolonged – up to three days, so the dog may need to be hospitalised throughout this time.
Theobromine has no specific antidote – cases are treated symptomatically. The prognosis depends on how much chocolate or cocoa powder the dog has eaten, and how long prior to being seen by the vet that the dog ate it.
Up to 50% of dogs will die if treatment is delayed until severe, persistent vomiting has developed. If seizures have begun then an even higher proportion of dogs will die.
Treated early enough, except for dogs that have consumed very large quantities of chocolate or cocoa powder, the outlook is generally quite good. Recovered dogs show no long term ill effects from the poisoning.