Other than the fact that you need to bring him immediately to the veterinarian, here are certain things you need to do prior to taking him.

1. Gather the evidence. If possible, determine what medicine your dog swallowed. It's also best to bring a sample packaging of it with you.

2. Prepare to give your veterinarian your dog's medical history and how it happened.

3. Try to take a sample of the vomit with you.