Lumps and Bumps – Nov 2024

WE CALL THEM TUMORS. Technically, most lumps and bumps you feel on your pet’s body, in or underneath the skin, are neoplastic tumors. What that means is they are “cancerous” cells multiplying at an unreasonable, unregulated, and abnormal rate. Some will be benign tumors, meaning that they will grow where they started, usually slowly; and that they are not likely to spread to other parts of the body by “metastasis” though the blood or lymph streams. Some will be malignant tumors, meaning that they will grow more aggressively where they started, are more likely to spread to other parts of the body (such as lungs, liver, spleen, bones, brain), and generally grow faster than benign tumors. Speed of growth does not dictate “good vs. bad” tumors, and size does not dictate “good vs. bad tumors.

There certainly are other disease conditions that can feel like a lump in or under the skin. Scar tissue from an injury or inflammation from a bug bite or an injection of medication are other common lumps and bumps. The difference with these abnormalities is they do not get bigger (they tend to shrink over days to weeks), and they often have a very clear explanation.

WHY SHOULD YOU CARE ABOUT LUMPS AND BUMPS?

Speaking as a board-certified surgeon specifically, and as a veterinarian generally, early action taken on a lump, in or under the skin, is dramatically more beneficial to your pet’s health and well-being (and your pocketbook and time) than “waiting and seeing” how big a lump can get before you act. I do surgery because I generally want to help animals live and be healthy and happy (and I took an oath to “above all do no harm”). I do surgery specifically because I like a challenging, highly technical occupation—very large tumors are certainly challenging!

I would trade away that professional challenge, for a simple procedure, in a heartbeat knowing the simple procedure will do your pet less harm.

(If you are squeamish about medical abnormalities, best you stop here. 😐)

Below are photos of big tumors (literally very large), and tumors that are big-for-their- location (meaning they may look like just a golf ball, but they are growing on a leg the size of your thumb!)

Tumors in these locations (skin or just under the skin) are most commonly either “soft tissue sarcomas” or “mast cell tumors” or “lipomas”. Lipomas deserve their own mention, simply because they are quite benign and soooooooo common. And because they are benign and sooooooooo common, they lull us into a sense of no urgency and no action.

My writing space and your boredom ( 😊 ) prevent me from creating an exhaustive treatise on these types of tumors, but below are some take-away points you can consider:

• Don’t wait, aspirate! (see online “Dr. Sue Cancer Vet”)
• If your dog is 4lbs soaking wet, size recommendations below are likely smaller!
•  If a lump is 1⁄4-1/2 inch in size, it is worth it to have it sampled with a needle and sent to a laboratory. (These are useful tests, not just padding a bill!)
• If a lump is a tumor, it deserves some attention.
• That “attention” will look different based on each scenario, but knowledge is power well beyond “just watch it”.
• Benign lipomas are a dime a dozen, so removing them all does not make medical sense for your dog. Tested/confirmed lipomas getting bigger and bigger, still deserve attention early rather than later.
• Surgical recommendation for “cure” of malignant tumor is to remove a 3cm “margin” of normal skin tissue around the tumor (1cm tumor, 3cm one side, 3cm other side = 7cm wide hole in skin; get out a ruler—that’s big surgery to your pet.)
• Surgical recommendation for “cure” of malignant tumor is to remove one normal layer of “barrier tissue” beneath the tumor (depending on location, that barrier tissue might be a leg bone, an ear flap cartilage or “just” an extra muscle belly.) Big is bad here too!
• Location matters—take a tumor off a toe sooner/smaller than a tumor off a flank.
• But size matters too—I say, take a tumor off any body location before it is larger than 1in/2cm (this number is probably more related to the art of surgery than the science of surgery; when I mentally balance “no big deal” surgery with “big deal” surgery and risks of any surgery, that number tumbles out.)
• As these tumors get larger or when located in a spot that bumps the ground, the skin will be damaged and weepy wounds will develop. These get infected and smell and leak…and can get really ugly in the hygiene department. You and your dog will not like this scenario

• We cannot see the future for your specific pet. We can only predict the likelihood of some future medical problem based on some data from your pet (aspirate test) and published scientific studies that have followed a large group of pet’s with similar data. **We can increase our ability to predict the future with more data from your pet; a tissue biopsy provides dramatically more information (but requires a minor surgery procedure to collect the sample).
• We can fix these. Even when quite large, we can make your pet better—it just takes more surgical effort and anesthesia time from us; and recovery care from you

• Difficult location tumors, such as leg and face, may require 2-3 procedures to fully cover the removal location with skin. Some difficult locations can be managed with “second intention healing” when we cover the removal location with a bandage and let the skin creep across to cover the site over 1-2mo.
• Damage control procedures (“palliative” surgery) are always an option in large or difficult location tumors when simpler recovery care is needed (for medical, logistical or financial reasons); “cure” is not the goal.

• If/when we say “watch it”, it makes medical sense to watch a lump that already has had an aspirate test. And watching is for weeks, maybe months, but not usually years! If it is a suspected tumor on aspirate test and still there at 1” or so, start thinking — quick and easy removal.

There are many other considerations with faced with lumps and bumps, but the above information scratches the surface of “taking action” and why. Have the discussion with your veterinarian, get comfortable with your decisions and plan, and then work your plan for when they “don’t just go away”. Less is more, as they say!

Lara Marie Rasmussen, DVM, MS
Diplomate, American College of Veterinary Surgeons
Direct Veterinary Surgery, LLC