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My dog has a bleeding lump on his back. Is it serious and what to do?

Updated On September 23rd, 2025

Pet's info: Dog | Labrador Retriever | Male

My dog has a lump on his lower back which is about 0.5cm wide. It has been there for 2 days now. It seems to have a centre of which it bleeds from and we have no clue as to what it is or the cause of it

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2 Answers

Most Helpful Answer

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Answered By Laura Johnson VMD

Veterinarian

Published on September 11th, 2017

Hi, thanks for using Petco Pet Education Center, formerly Petcoach! Thanks for the pictures! Many skin masses can look the same. Red dermal masses, like this one, can be benign or malignant. Some possibilities are an inflamed sebaceous adenoma, hemangioma, histiocytoma or it could be a Mast Cell Tumor. Since it showed up quickly I would have Oscar seen by your Vet. They can decide if aspirating it (sticking it with a needle and sending the slides to the lab) or removing the mass and sending it for biopsy is best. I hope this helps and I wish you and Oscar the best!

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    Answered By Jenna Beyer, DVM, MBA, cVMA

    Veterinarian, Certified Veterinary Acupuncturist

    Published on August 8th, 2017

    That looks like a very large mass. I would recommend that you take Slat to the vet for evaluation. The shiny surface looks like it is starting to ulcerate, and I am sure it is very painful. Make sure that he isn't licking it as that can cause infection and more issues. Your vet may use a needle to collect a few cells to look at under the microscope to determine if there is an infectious cause (bacterial or fungal) or cancerous cause (benign or malignant). Based on that information, a treatment plan could be made.

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