It is unethical and illegal for a dog to determine a diagnosis via phone. Unless a dog has been physically examined by a vet, it is impossible to come up with an accurate diagnosis and a rational plan of treatment. A veterinarian cannot provide a diagnosis based solely on the symptoms observed by the dog owner. A dog's external symptoms can be indicative of the cause of many internal diseases, with a variety of diagnostic treatments. A complete physical exam is required along with diagnostic tests to determine the best way to treat and cause the symptoms of a dog's illness.