The aim of the second edition of this atlas was to improve and update both the images, many of which are new, and the written content, including the latest developments in diagnosis and treatment. Some clinical features that were not included in the first edition have also been added. This atlas has always been intended to help clinicians to recognise the different dermatoses they may see in daily clinical practice. Although dermatology is based on direct observation of the affected organ, which should theoretically make diagnosis easier, it is notably difficult to find pathognomonic images of a given disease, and we must always consider the differential diagnoses when suspecting whichever is most likely. One of the advantages of this book, therefore, is that it links clinical features and presentations to the corresponding dermatological patterns and the probable diagnoses that could match them. In this second edition, we have expanded the range of photographs, many of which are accompanied by the corresponding cytology results or microscopic images that could help bring the diagnosis to light. As the author of this atlas, I would be delighted if it helped veterinarians to reach diagnoses and resolve their cases.