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Why does my dog have a hard, black, painful bump on his back?

Updated on September 23rd, 2025

Pet's info: Dog | American Pit Bull Terrier | Male | unneutered | 9 months and 10 days old | 38 lbs

My dog has a bump on his back; it has a black top (his coat is white and gray); it feels hard to the touch and doesn't move a lot, he allows me touch the area but looks at me when I do, like it bothers him a little.

4 Answers

Most Helpful Answer

Answered By Ricardo Fernandez, DVM

Veterinarian, Veterinary Oncology Resident

Published on August 9th, 2018

Thanks for using Petco Pet Education Center, formerly Petcoach! This could be a benign or malignant growth. This could even be an abscess. There is no way of knowing what it is just based on its appearance. This is often differentiated by a test called a fine needle aspirate (FNA) which is a pain free, inexpensive and easy procedure which in most cases will help reach a diagnosis. Sometimes a biopsy is needed for a definitive diagnosis. I recommend that you have him evaluated by your veterinarian for further assessment and treatment. I am really hoping for something benign. Good luck and have a good night!

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Jessica Keay, DVM
Veterinarian
Published on July 2nd, 2018
There are many different causes for dermal masses as you describe. Many are benign growths such as sebaceous adenomas, which do not spread or cause problems elsewhere. We can, however have more aggressive growths affect the skin so for this reason a vet exam is recommended. Depending on the appearance the vet may recommend monitoring the growth for changes, as aspirate to perform cytology to help identify the growth, or removal and biopsy.
1Pet Parents found this answer helpful
Answered By Jenny, DVM
Veterinarian
Published on December 16th, 2017
It has been for some time. Is it changing in any way or getting larger? If it looks and feels the same without getting larger and causing him any discomfort then the chances of it being cancer are drastically reduced and unlikely. It may be a cyst if that is the case. If you do notice it changing or getting larger then you will need your vet to aspirate some cells to see what it is made up of to see if surgery is needed to remove it or you can continue to monitor it.
1Pet Parents found this answer helpful
Answered By Daniel Fonza, DVM
Veterinarian
Published on October 1st, 2017
Hi there and thank you for using pet coach to address your concern. What you are seeing looks to be a benign skin mass. It looks like what we call sebaceous adenomas, basically a benign mass of the glands in the skin. This is not a tick and I would not be alarmed by this. If it continues to grow in size, drastically change in appearance or all of a sudden it is bothering him, I would have a veterinarian examined him to perform additional tests on this Mass to ensure it is nothing to be concerned about. I hope this helps! Please feel free to contact me with any other questions or concerns that you may have.
1Pet Parents found this answer helpful

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