Many diseases can have different presentations.
The spectrum of clinical signs is limited and affected by chronic change and selftrauma. It is therefore very important to look for primary lesions, where present, and to be able to distinguish them from secondary lesions. A good history is also crucial in dermatology, especially in a chronic case, in order to rule in or out specific diseases. It is useful to make a note of the breed since certain diseases have an identified heritable basis or simply occur more frequently in some breeds. The age of onset of a dermatological disease is important.