It would seem that dogs have more of a taste for chocolate than cats but chocolate is actually poisonous to both.
The poisonous compound in chocolate is called theobromine and naturally occurs in the cacao pod. The higher the chocolate content the more theobromine there is, for this reason dark chocolate is more poisonous than milk chocolate.
The amount of Theobromine to cause poisoning is in the region of 100-150 milligrams per kilogram of bodyweight, If you have a collie weighing 20kg as little as 2000mg of theobromine could be fatal without urgent veterinary treatment. If you bare in mind that 3000mg of theobromine can be found in one 500 gram bar of chocolate you can see how little dark chocolate needs to be eaten to have a potentially lethal situation.
Once a dog has a taste for chocolate (just like us) they become addicted and crave chocolate. This takes some careful management as Karen and her family found out. Karen’s dog Flash ate more than a fatal dose of chocolate, thanks to them quickly getting him to us we managed to successfully treat him, even so, it was touch and go for a while. Now Flash actively scouts the house for chocolate.
If you think your dog has eaten chocolate then you should call your vet straight away, preferably with an idea of how much chocolate has been eaten.
A small amount of chocolate will probably only cause gastroenteritis- vomiting and or diarrhoea.
Small amounts of high quality dark chocolate or a lot of milk chocolate, the theobromine can produce muscle tremors, seizures, an irregular heartbeat, internal bleeding or a heart attack. The onset of theobromine poisoning is usually marked by severe hyperactivity.
Calling the vet straight away if you suspect your dog has eaten chocolate is essential as successful treatment for theobromine poisoning is to empty the stomach (often by induction of vomiting) within two hours of ingestion.
Sensitivity to grapes, raisins, sultanas and currants depends on the individual, some dogs can eat quite a lot without any ill effects while others only have to have a very small amount to be left with permanent kidney damage. That is only evident days after eating the grapes.
This is why we can never take the risk of seeing how they are. If you suspect your dog has eaten grapes in their fresh or dried forms then contact your vet as soon as possible.
Treatment is in the form of support for your dogs kidneys to help prevent permanent damage.
Foods to avoid are fresh grapes (we have had two dogs in the last couple of months being tempted by fresh grapes in the fruit bowl), Simnel cake, hot crossed buns and especially chocolate covered raisins.