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My dog has a painless, growing neck lump after vaccine. What's next?

Updated On September 23rd, 2025

Pet's info: Dog | American Bully | Male | unneutered | 3 months and 22 days old

My fur baby has had a golf sized lump on the back of his neck for about a week now but he doesn’t present with any pain or tenderness when we touch it. Today it seems to have gotten a little bigger. The only thing we can think of is his immunization he got about 2 weeks ago in that area or a bee sting. What should we do for Aries?

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1 Answer

Most Helpful Answer

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Answered By Ann Dion, DVM

Veterinarian

Published on November 25th, 2018

Hello and welcome to Petco Pet Education Center, formerly Petcoach. Lumps and bumps can be many different things, including inflammation (reaction to vaccine is possible), infections (this could be a small pocket of pus), tumors that are both cancerous and not-cancerous, foreign objects stuck inside the body causing inflammation/infection, etc. I recommend you have your boy back to your vet where you had the vaccine and have them check to make sure it's nothing serious. They will likely put a needle in the mass and see what type of material is present inside, and this will lead their treatment plan. This doesn't present like a bee sting. Best of luck with your boy!

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