Prior to planning surgery, it is essential to obtain a diagnosis of the tumor type. Cytology can often (about 75%) provide a diagnosis, but biopsy is more accurate (about 95%). We will review different techniques for obtaining a biopsy from FNA to excisional biopsy. Once we have a diagnosis, we use tumor behavior to determine an appropriate surgical dose. For benign tumors, marginal excision is usually curative. Unfortunately, for exotic animal species, we do not have a lot of data on tumor behavior and often recommendations for dogs and cats are not appropriate for small exotic animal patients.