If you think your dog has been poisoned, the first thing you should do is call the Animal Poison Control Center at 1-888-426-4435. They will ask you to describe the symptoms your dog is experiencing.
Note: Animal Poison Central may charge a consultation fee.
The next step is to try to figure out what type of poison the dog ingested. Poison control may be able to narrow it down based on your dogs' symptoms. Watch their vomit and stool for color as well as parts of anything they ate. If you can't identify the substance this way, look around your house and your yard for anything they might have eaten. If you can identify the poison, you will be directed to make your dog vomit or give charcoal depending on the poison. If you need your dog to vomit, you can use salt water or diluted hydrogen peroxide. You can find activated charcoal at most drug stores. It can also be used in many cases of human poisoning, so it is a good thing to have in your medicine cabinet. You may be directed to take your dog to the vet, or you may be able to treat him at home.
You should write the Poison Control number and the common symptoms down so that you can use it for quick reference if you ever need it. You should also keep activated charcoal and learn the household products that can be hazardous to your pet.