Meghann Hugo, MN 4/2/2011 7:26:21 PM This happened to my brothers dog today so we gave him the hydrogen peroxide and then got him to the emergency vet. The ER vet was very unhappy that he had the hydrogen peroxide and said it can cause more damage and it should not be given. Sometimes dogs do not vomit from it and it sits in their stomach and causes more trouble. My suggestion is to call poison control or a vet before you give them anything. My brothers dog had his stomach pumped within 2-3 hours of eating the rat poison and should be fine. He was also given a lot of water which apparently helped.