Biopsy – Histological examination of tissue biopsies frequently leads to a definitive diagnosis of disease. Tissue biopsies are typically obtained at the time of surgical removal of soft tissue masses from the body. Samples are placed in a transport solution (10% formalin) for transport to the outside reference laboratory where microscopic slides are prepared and are read by a board-certified veterinary pathologist. Results are faxed to the clinic, usually within a day or two. The image below left is a benign papilloma (wart) and the image below right reveals the black pigment characteristic of a melanoma.