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My dog has a hard, baseball-sized lump on his back. What should I do?

Updated on September 23rd, 2025

Pet's info: Dog | Dogo Argentino | Male | 3 years and 8 months old | 70 lbs

My dog has a baseball size lump in his back. This developed in within 60 days. We didn't see any changes in his personality or behavior at all , nor to the way he eats or sleep. The lump is not a bother to him as I touch it without any reaction to pain or any indication or infection. The mass of the lump is hard and the diameter is like a baseball.

1 Answer

Most Helpful Answer

Dr. Melanie, BVSc MS

Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on April 20th, 2018

This lump on Messi could be a cyst, a benign tumor, or a malignant tumor. Any suspicious lumps should be examined by the vet. The vet can perform a test called a fine needle aspirate on it. To do this, the vet sticks a small needle into the lump to get a sample of it's cells, and examines the cells on a slide under a microscope. It's usually painless to the animal, and relatively quick to perform. Given that it has developed within the past 60 days and gotten as large as a baseball, I would give your vet a call first thing in the morning to make an appointment to have this seen and treated. Best of luck!
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