Our dogs can be great gardeners, cupboard emptiers, food thieves and bin surfers. They are opportunists and see a cake left to cool or a nice smelling bin as fair game! The problem with this is that by doing this they may eat or drink something that is poisonous to them, and without immediate veterinary attention, the consequences could be fatal. The best prevention is to ensure that your house and garden is ‘dog safe’ and that you do not leave anything within their reach.
I have attached 2 very good links that outline many everyday plants/food etc. that are poisonous to our dogs. Our first reaction maybe to make our dogs vomit after having eaten a poisonous item, but never ever do this without instruction from your vet, you could damage the health of your dog further and complicate an already serious condition. If you suspect that your dog has ingested anything that is harmful to them, get them to a vet immediately.