Will a 30 kg dog be ok after eating 20Mg of Valium?

Maybe - it would be best to notify your veterinarian of the accidental ingestion immediately. Your veterinarian can then tell you what to watch for to know if your dog is having a problem. There are other factors that influence whether a dog of a certain size will have a reaction to a certain dose of a drug, including age, health status, breed and any other medications or treatment he might be receiving.