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How to tell if my dog's leg lump is cancer or a benign growth?

Updated On September 23rd, 2025

Pet's info: Dog | German Shepherd | Female | spayed | 7 years old | 85 lbs

my dog has a single lump on her right rear leg, on the toe second from the left. it is about 4mm in diameter and it has normal hair growing out of it because the lump occupies a place where my dog has hair on her toes. i have read about interdigital furunculus, to mast cell tumor and frankly they all scare the bejesus outta me. what are some factors/symptoms that would differentiate between mast cell or scary cancers and non scary benign growths?

4 Answers

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on February 17th, 2017

I can understand being worried about Benny, but I wouldn't get freaked out. The best way for you to know if this lump on her leg is to have her seen by a vet. The vet can perform a test called a fine needle aspirate on it. To do this, the vet sticks a small needle into the lump to get a sample of it's cells, and examines the cells on a slide under a microscope. It's usually painless to the animal, and relatively quick to perform. This test may help differential between a malignant tumor or a benign one. I say "may" because some tumor types need a biopsy to diagnose them, and the vet can recommend having that done if needed. Have this lump examined and diagnosed by a vet, and then they can discuss treatment options with you.

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Other Answers

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on September 18th, 2019

    Unfortunately I cannot make a diagnosis from a picture, but it could just be a benign growth. Any suspicious lumps should be examined by the vet. The vet can perform a test called a fine needle aspirate on it. To do this, the vet sticks a small needle into the lump to get a sample of its cells, and examines the cells on a slide under a microscope. It's usually painless to the animal, and relatively quick to perform. Once the cause of the lump is diagnosed, the vet can discuss treatment options if needed. Give Lulu's vet a call to make her an appointment.

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on November 25th, 2018

    This could simply be a benign growth, but it is concerning that it is growing. Any suspicious lumps should be examined by the vet. The vet can perform a test called a fine needle aspirate on it. To do this, the vet sticks a small needle into the lump to get a sample of its cells, and examines the cells on a slide under a microscope. It's usually painless to the animal, and relatively quick to perform. Once the cause of the lump is diagnosed, the vet can discuss treatment options if needed. I'd make an appointment with her vet to have this done. Best of luck.

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    Answered By Ricardo Fernandez, DVM

    Veterinarian, Veterinary Oncology Resident

    Published on August 30th, 2017

    Hi there! Thanks for using Petco Pet Education Center, formerly Petcoach! This could be a benign growth or a malignant growth such as a mast cell tumor, melanoma, among many other possibilities. I recommend you have Herman evaluated by your veterinarian for a test called fine needle aspirate which is an easy, quick and pain-free procedure which in the majority of cases will help reach a diagnosis to identify what the best course of action is based on the findings. In some cases, a biopsy is needed for a diagnosis. If it truly is benign then removal is not necessarily recommended. However, if it is malignant and it has not spread to other locations, then surgical removal is recommended. Good luck! Keeping my fingers crossed that it is something benign.

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