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My dog has a round lump under his skin near his tail. Is it serious?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed Small (up to 22lb) | Male | unneutered | 7 months and 28 days old | 3 lbs

Found this at the base of his tail near hind quarter. If I grab it it feels like a small round lump below the skin.

1 Answer

Most Helpful Answer

Answered By Lauren Jones VMD

Veterinarian

Published on May 31st, 2019

Without examining Aero and performing diagnostic tests, I can't definitively say what the cause of this lesion may be. However, some possible causes include a follicular cyst (a benign fluid filled lesion under the skin that can feel hard), sebaceous cyst (a benign oil/sebum filled cyst), inflammatory lesion from trauma, or many other causes. Given Aero's young age, cancerous lesions are very unlikely.

This is certainly not an emergency, but I do recommend taking Aero to his vet for further evaluation in the coming days to weeks. Your vet will be able to examine him and will likely need to perform a fine needle aspirate, which involves using a needle to draw out a few cells from the lesion for microscopic evaluation. Based on these results, your vet will be able to determine the best course of treatment. In the meantime, keep a close eye on the lesion for any sudden growth, redness or discharge. If Aero begins to lick at the lesion, put an e-collar (cone) on him until his vet visit, as licking could result in infection of the lesion. I hope this helps and that all goes well!

1Pet Parents found this answer helpful

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