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My dog has a new lump behind his knee. Should I worry about cancer?

Updated On September 23rd, 2025

My dog developed a lump behind his right knee. It's about the size of a quarter and it wasn't there yesterday. He is a three year old neutered blue heeler mix who has had no previous health problems. How likely is it to be lymphoma?

2 Answers

Most Helpful Answer

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Answered By Rebecca, DVM

Veterinarian

Published on August 22nd, 2017

I would recommend a vet visit. The vet can do a needle aspirate and take a look at the cells. While this may be a location for a lymph node it does not necessarily have to be lymphoma. Enlarged lymph nodes may be due to cancer, or inflammation or infection. Or it's possible it's not a lymph node and may be another type of mass or swelling. I recommend a vet visit to try to see what is swollen and why.

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    Answered By Laura Johnson VMD

    Veterinarian

    Published on

    Hi, thanks for using Petco Pet Education Center, formerly Petcoach! If it is the only lymph node enlarged probably unlikely to be lymphoma. There are many causes for lumps under the skin: it could be a fatty deposit, skin infection, a cyst or a benign growth. Since it is sudden it is not wrong to have your Vet take a look at the lump. I wish you the best of luck!

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