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My dog has a red, uncomfortable lump on her back leg. What is it?

Updated On September 23rd, 2025

Pet's info: Dog | Irish Terrier | Female | unspayed | 4 years and 2 months old | 18.739 lbs

Ive found a lump on my dogs back leg like a ball its red and she seems abit uncomfortable me touching it what cud this be?

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3 Answers

Most Helpful Answer

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Answered By Linda G, MS, DVM

Veterinarian

Published on November 30th, 2017

Hello, this looks like a histiocytoma, a benign tumor. Fairly common in younger dogs, it usually spontaneously regresses without treatment. Have your veterinarian take a look to make sure that it is not anything else. Thank you for using Petco Pet Education Center, formerly Petcoach.

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    Answered By Jessica Keay, DVM

    Veterinarian

    Published on April 13th, 2018

    Thank you for your question. Histiocytomas most often are red ulcerated lesions, which this does not appear to be. They also most often appear in animals 2 years of age and younger. You can read more about the growths at http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=1676. I would recommend having your vet take a look at the growth. They may recommend what is called a fine needle aspirate, which involves sticking a small needle into the growth to collect cells (can usually be done awake with minimal discomfort) to help identify the type of growth, which helps us determine if it should be removed or just monitored.

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    Answered By Lauren Jones VMD

    Veterinarian

    Published on May 23rd, 2017

    One of the more common red, raised lumps in young dogs is a histiocytoma. These are benign masses that go away without intervention in 2-3 months. However, Hercules' skin lesion could also be related to a malignant mass, cyst, ringworm, skin infection, among others. Your best bet is to take him to the vet for an exam and evaluation of this lesion - better safe than sorry. I hope that all goes well!

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