In achieving a successful treatment in animals there are many factors that must be examined by a veterinarian. These elements, often neglected, are the difference between being or not successful in their therapeutical management. For these reasons, in this LLL paper it was envisaged a remembrance of useful major practical issues related to: drug formulation, dosage regimens, safety limit, counter-indications, side effects, drug interactions etc., and the associations of good nature which are reach practitioners in the field.