Due to the fact that in Colombia neither a program nor a center for monitoring adverse reactions to drugs (ARD) in animais exist, the aim of this work was to carry out a global characterization of the State of ARD in dogs in veterinary clinics at Tunja and Bogota. This work is the first of a group of proposals which have been constructed in order to support the development of a center for drug surveillance. Data were collected personally at selected veterinary clinics by filling out a questionnaire. According to the results, 40 ARD's were reported, characterized by allergic reactions, as well as digestive, neurological, cardiovascular and dermatological alterations. The groups of pharmaceuticals associated with these effects comprised vaccines, antibacterials, antiparasitics, INSAID 's, vitamins and CNS depressors. With this study it was concluded that ARD 's are an important group of pathologies in canines, worthwhile to pay attention to with higher responsibility. Likewise, a lack of attention was found in recording and notificaron of ARD by the veterinarians. The importance to create a center for surveillance of veterinary drugs in Colombia is ratified.