PLEASE NOTE A NEW 4TH EDITION HAS BEEN PUBLISHED AND IS AVAILABLE IN THE LIBRARY AND IN PRINT

Nodules and sinus tracts are common signs in small animal dermatology and are the manifestation of a diverse group of underlying pathological processes, some of which may be common, as in a cat bite abscess, or rare, as in the case of some mycoses. Nodules are solid, cystic or oedematous elevations of the skin that may extend into the subcutis, panniculus and/or muscle. Microscopically, they are made up of accumulations of cells and fluid within the epidermis, dermis and hypodermis. These cells may be neoplastic, inflammatory/reactive or both. Disruption of the epidermis over nodules occurs frequently as a result of inflammation or ischaemia. The clinical features associated with the necrosis and inflammation are sinus tracts and/or ulceration. The chapter looks at the following: Differential diagnosis; and Clinical approach.