Lumps & Bumps — What To Do If Your Dog Has a Mass Under Their Skin

Author: Dr. Jason Nicholas

Published: February 3, 2015

Updated: January 30, 2021

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checking for lumps on your petMany pets, especially as they age, grow little lumps and bumps on the surface of their skin or just under their skin, in what’s called the subcutaneous space. Such growths can be all kinds of things from benign (not harmful), although potentially unsightly, “skin tags” and cysts to bug bites or masses, which themselves can be either benign or problematic.

It's always best to play it safe

The best thing to do when confronted by a new lump or bump is to bring your pet to the vet so that your vet can evaluate the new growth. They’ll feel it, measure it, document it in your pet’s record, and likely even recommend doing a “fine needle aspirate” to begin to get a sense of what it might be.

Lumps: Take Note, Take Measure, Take Pictures

dog-lump-on-legWhat are you to do when your schedule or finances prevent you from going to the vet for each new growth? This is a very real question that pet owners face.Here are some tips to help you keep track of those lumps & bumps, and to begin to figure out which ones you might be able to wait on and which you definitely shouldn’t.

  • Using electric clippers or an electric beard trimmer, slowly and carefully remove the fur from around the growth. Use extreme caution with any masses around the eyes, as the clippers or the falling fur can damage the eye. And NEVER use scissors or a razor to remove fur from around any growths on your pet’s body, as you’re likely to wind up cutting their skin.

  • Use a ruler, or calipers, to measure the size of the growth when you first notice it. Be sure to record the size and note the date and location on your pet’s body, too. Remeasure frequently to monitor for growth.

  • Use a Sharpie marker to trace the outline of the growth. This is a quick and highly visual way to know if and when a growth starts to increase in size. The mark will fade over time but in the short term it will help you identify a fast growing mass.

  • Take a picture of the growth. Be sure to put a ruler or an object of a known and fixed size (such as a coin) next to the growth and in the frame of the picture, so as to better gauge the size later.

Some indications that you definitely shouldn’t delay veterinary evaluation

  • The lump is growing rapidly, ulcerating or bleeding, or otherwise causing your pet discomfort.
  • The lump is purplish-red or darkly colored.
  • The growth is associated with or near the mammary (breast) tissue of a female pet.
  • The growth is on your pet’s ear or nose, or in their mouth.
  • Your pet has a history of malignant skin tumors.
  • Your dog is a breed that is predisposed to skin cancers.
  • Your pet exhibits a decrease in energy, appetite, or weight coincident with the development or growth of the mass.
  • Your pet starts vomiting, having diarrhea, or coughing.
  • Your dog is showing signs of pain.


Again, earlier veterinary evaluation is always the safest bet. The "lump" in the photo above, looks rather "innocent" but it ended up being cancer. You can read more about it on Orchard Veterinary Group's site. But if you need to delay, for whatever reason, please take into account the tips and rough guidelines above.

And - whatever you do - regardless of the size, location, or cooperation level of your pet…  PLEASE never attempt to remove, squeeze, or cut off a lump yourself! It's alarming how many people do this.

About the author

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Dr. Jason Nicholas

Dr. Nicholas graduated with honors from The Royal Veterinary College in London, England and completed his Internship at the Animal Medical Center in New York City. He currently lives in the Pacific Northwest.

Dr. Nicholas spent many years as an emergency and general practice veterinarian obsessed with keeping pets safe and healthy. He is the author of Preventive Vet’s 101 Essential Tips book series.

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