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My dog has itchy lumps under his arm. When should I be concerned?

Updated on September 23rd, 2025

Pet's info: Dog | Labrador Retriever | Male | neutered | 8 years and 7 months old | 95 lbs

Hello I have an 8yr old Labrador A while back I noticed he had a lump under his arm, after a week it became two lumps. It's not noticeable, and does not seem to hurt him. We also live in a ranch, so I'm not sure if it could be a bug bite or something way more serious. He's been acting very normal super active but just a little itchy on that area. What should I do?

4 Answers

Most Helpful Answer

Answered By Dr. Davis

Veterinarian

Published on August 19th, 2017

I am concerned about those lumps. Being itchy in that area could be from insect bites or he could have had a puncture wound that became infected. Those generally would be more red and uncomfortable. There are lymph nodes and lots of vessels and nerves in that location. Definitely I would take him to your veterinarian to have these examined and they may take some cells through a needle aspirate to diagnosis whether it is infection or a cancer. Then when they know what it is they can decide on the best treatment. This could be serious so I wouldn't wait too long as treating most problems early is most effective. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Junior.

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Daniel Fonza, DVM
Veterinarian
Hello and thank you for your post! If you are feeling a lump and are concerned, you can have your vet examine this and do some additional testing to help determine if it is benign or malignant. A simple test that we can do is insert a small needle into the mass and look at the cells under a microscope to see whether or not it is something to be concerned about. It looks like a fatty tumor (lipoma) but difficult to tell since I am unable to feel it myself. Please do not hesitate to contact me if you have any other questions or concerns. I am also available via text / phone consultation if needed.
1Pet Parents found this answer helpful
Answered By Dr. Elizabeth
Veterinarian
Published on September 21st, 2019
Pets can get many types of lumps and bumps. Most of these tumors will be benign but some will be malignant and you can't tell by looks. Here is a helpful link discussing the various types of skin masses in general:
https://www.petcoach.co/article/lumps-and-bumps-on-your-pet/

Since the mass seems to be bothering her, I do recommend to have it checked out to be safe. There is a type of skin cancer called a mast Cell Tumor which is frequently itchy. The doctor may recommend to aspirate the mass to examine the cells under a microscope. That is one of the best ways to know what it is and if further action is needed. You may look into financing through Care Credit or Scratch Pay. You may find more information on their websites. Hopefully it's nothing serious.
1Pet Parents found this answer helpful
Answered By Dr. Elizabeth
Veterinarian
Published on February 12th, 2019
That looks like a mass or perhaps a very inflamed tick or spider bite. It’s impossible to say based on the photo. Regardless the area looks very angry and I recommend to have Scout seen by his veterinarian within the next 24 hours. If it is a skin mass, the doctor will likely recommend to aspirate the tissue to check for a skin cancer called a Mast Cell tumor. If it is more related to a bug bite, it’s possible that area is infected. Make sure Scout does not lick at that area as it will make it worse. I hope this is helpful and please feel free to post any additional questions!
1Pet Parents found this answer helpful

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