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My dog's leg lump is changing color and size. What should I do?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed Small (up to 22lb) | Female | spayed | 12 years and 4 months old | 15 lbs

We recently discovered a lump on our dogs leg. It started to shrink yesterday but today grew larger and changed from pink to purple.

4 Answers

Most Helpful Answer

Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on May 27th, 2020

Thank you for contacting Petco Pet Education Center, formerly Petcoach with your question about Lady. This lump could be a cyst, a benign growth, or a malignant 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 her vet a call to make her an appointment. I hope this helps!

3Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Dr. Melanie, BVSc MS
Veterinarian
Published on July 14th, 2017
Please keep in mind that without seeing the lump in person, or even a picture of it, there's no way I can say for sure what it could be. The lump on Joni could be a benign tumor, due to a foreign body such as a grass seed, a cyst, or even a malignant tumor (unfortunately always a possibility in a middle aged dog). the only way to know for sure 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. I would take her into the vet on Monday to diagnose what is causing the lump so it can be treated as needed.
1Pet Parents found this answer helpful
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.
1Pet Parents found this answer helpful
Answered By Ricardo Fernandez, DVM
Veterinarian, Veterinary Oncology Resident
Published on April 29th, 2018
Thanks for using Petco Pet Education Center, formerly Petcoach! This could be a benign or malignant growth. There is no way of knowing what it is just based on its appearance. This is often differentiated by a test called a fine needle aspirate (FNA) which is a pain free, inexpensive and easy procedure which in most cases will help reach a diagnosis. Sometimes a biopsy is needed for a definitive diagnosis. I recommend that you have her evaluated by your veterinarian for further assessment and treatment. I am really hoping for something benign. Good luck and have a good night!
1Pet Parents found this answer helpful

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