Cutaneous and subcutaneous masses are frequently found in dogs in small animal clinical practice. They are often discovered by the owner or by the vet during a general examination of the animal. The possibility to rapidly determine the nature of the mass allows a quick feedback to the owner and define the right therapeutic approach. Cytological evaluation represents the preferred method for obtaining samples from cutaneous and subcutaneous masses, because allow the vet, also in the clinic, to discriminate an inflammatory process from a neoplastic process. The cytological evaluation provides useful information regarding the type of cell responsible for the observed lesion. The test is quick and easy to perform as well as being economical, but obviously requires an executive capacity, to be able to provide quality samples, and above all, experience in reading the slides. In some cases, with the cytological evaluation and collected data the vet is able to give an accurate diagnosis or a diagnosis indication. In other cases, samples collected may not give a clear diagnosis indication, requiring the vet to perform more invasive tests, for example biopsy and histopathology evaluation. This thesis examines the cytologic characteristics of cutaneous and subcutaneous inflammatory lesions, neoplastic lesions and masses of other nature. The thesis also reports experienced cases observed at “Unità Operativa di Patologia Generale ed Anatomia Patologica Veterinaria” from September 2018 to June 2019.