I agree with Margot49, it is more likely to be blood, which is an indication of so many potential health issues, from ulcers to more serious complaints, that it would not be appropriate to comment here. It is vital you get your dog to a vet as soon as possible, so he can be properly assessed. Much also depends on how your dog is behaving when he is not vomiting. Does he behave normally? Does he still have the same level of energy? Is he sleeping more? These are questions your vet will undoubtedly ask you about, so be prepared. Also, what are you feeding him? Have you changed his diet recently or started giving him different treats to what were being given previously? If you can, collect a sample of the vomit in a washed-out jar and take this with you to your vet, so they can assess it and attempt a diagnosis. Please come back and let us know how you get on. Tony
Red bile? You sure that isn't blood?