Glossary

Biopsy

The removal of a small piece of tissue, or a sample of cells, for examination under a microscope to find out what a lump or abnormal tissue is.

Also called: tissue sample, fine needle aspirate, FNA, punch biopsy, histopathology, lump testing

A biopsy takes tissue from a lump, organ or skin area and sends it to a veterinary pathologist, who examines it under a microscope. It is the way to learn what a mass actually is, whether it is cancer and, if so, what type and grade, which shapes the options for care.

A fine needle aspirate, or FNA, is a quicker, lighter step in which a thin needle collects cells from a lump and needs no anesthesia in most dogs. It can answer many questions but sometimes does not give enough information. Larger samples, from a punch tool or surgery, are done under sedation or anesthesia and give more detail.

A lump cannot be judged by its look or feel. Ask the vet to explain which test is planned and why, and how long results take.

Last reviewed November 8, 2026

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Related terms

Mast cell tumor The most common skin cancer in dogs, which can look like any lump, so every new skin lump should be sampled by a veterinarian. Lymphoma A cancer of the lymphocytes, a type of white blood cell, that most often appears as firm, painless swelling of lymph nodes. Osteosarcoma The most common bone cancer in dogs, an aggressive tumor that mainly affects large and giant breeds, often in a front leg. Anesthesia A medically induced, controlled loss of consciousness for surgery, dental cleaning or imaging, with monitoring throughout.