Why dog vomiting thick white substance, Why is my dog vomiting this thick white substance? this morning my dog started vomiting which is not normal at all for him to do. the substance is thick and white.. Dogs dog breeds - hubpages., Articles about dog breeds, training your dog, dog food, dog health, and dog grooming.. Dog constipation vomiting | ehow, Dog constipation and vomiting. constipation can be a serious problem for dogs of all ages and breeds. chronic constipation often leads to other symptoms and may.