Cat Tumor and Mass Removal Surgery

Katie Grzyb, DVM
By Katie Grzyb, DVM on Jul. 28, 2021

Lumps and bumps commonly occur on cats of any age. These masses can form anywhere inside and outside your cat’s body. Unfortunately, however, many lumps and bumps look and feel the same, whether they’re harmful to your cat or not.

To understand the risks associated with each mass and whether cat tumor removal is necessary, we must know the type of cells and the origin of the mass. Assuming that all masses are safe unless they are large or open can be risky, and without microscopic evaluation, determining cell type is impossible.

If your cat has a mass, your vet needs to perform a complete physical examination with microscopic evaluation of all masses to determine their origin, even if your cat has a history of benign (noncancerous) bumps.

Diagnosing Your Cat’s Tumor or Lump

A biopsy is necessary to definitively diagnose the cause of your cat’s tumor. A biopsy is a sample of the growth (and sometimes, requires the removal of the entire growth), which is sent to a lab for a pathologist to review. The pathologist (a specialist that diagnoses disease based on evaluating bodily fluids and tissue) can trace the origin of the tumor and provide a confirmed diagnosis.

This process will give your veterinarian information to determine the next best steps for your cat.

In some cases, your vet will recommend watching the growth and waiting to see if it changes. In other cases, a follow-up with a veterinary oncologist or board-certified veterinary surgeon may be needed.

Caring for Your Cat After Tumor Removal

Post-surgery care for the lump will depend on where it was located and the extent of the surgical procedure required to remove it.

Internal Tumors

If your cat had surgery to remove an internal tumor, then they need to rest for at least 10-14 days after surgery. After surgery, you must:

  • Monitor the incision for proper healing

  • Use an e-collar or recovery suit at all times

  • Give all medications, for pain and/or infection, as directed

  • Pay attention to your cat’s appetite and bathroom behavior

If your cat displays any of the following, contact your vet immediately. These could be signs of a surgical complication:

  • Refusing food

  • Discharge or swelling at the surgical site

  • Sluggishness

  • Changes in breathing rate

  • Pale gums

  • Vomiting or diarrhea

  • Not peeing or pooping or urinating more frequently or in inappropriate places

Surface Lumps

If the lump was removed from your cat’s skin, then you must monitor the surgical site.

Depending on how much tissue was removed and from what area, fluid can accumulate under your cat’s skin, causing a sagging appearance, or even leakage, through the incision.

If you see this, call your veterinarian right away. This can be a sign of infection or something called a seroma (buildup of fluid), which may require further monitoring and care.

These other signs also warrant a call to the vet:

  • Swelling

  • Redness

  • Pain

  • Discharge

  • Early loosening of stitches

If bandages are used to protect the incision, they must remain dry and in place. Follow your vet’s instructions on when they should be removed during recheck examination.

If a bandage prematurely comes loose or becomes soiled or wet, call your vet to ask what to do. This may mean a quick trip to your vet’s office for a recheck and replacement bandage, or your vet may clear the bandages for early removal. 

Katie Grzyb, DVM


Katie Grzyb, DVM


Dr. Katie Grzyb received her Doctorate of Veterinary Medicine from Ross University in 2009. She continued her clinical training at...

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