Not only is it unethical and illegal to prescribe for an animal that has not been physically examined by a veterinarian, it is also impossible to accurately diagnosis and determine a rational plan of treatment.
A veterinarian cannot make a diagnoses based on symptoms only as observed by an owner. The outward signs may be an indication of any number of internal causes with a wide variety of clinical treatments. A complete physical examination and other diagnostic tests are required to determine the cause of the symptoms and the appropriate course of treatment.