What should I do if my pet has a lump or bump?

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Last updated: July 13, 2025View editorial policy

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What To Do If Your Pet Has a Lump or Bump

If you discover a lump or bump on your pet, you should have it examined by a veterinarian as soon as possible to rule out cancer and determine appropriate treatment.

Initial Assessment

When you find a lump on your pet, take note of the following characteristics:

  • Size (measure if possible)
  • Location on the body
  • Texture (soft, firm, movable, fixed)
  • Any changes in the skin over the lump (redness, ulceration)
  • How long it has been present
  • Whether it has changed in size or appearance
  • Whether it seems painful to your pet

Veterinary Evaluation

Diagnostic Process

  1. Physical examination: The veterinarian will examine the lump and assess its characteristics.

  2. Fine needle aspiration: Often the first diagnostic step, where a small needle is used to collect cells from the lump for microscopic examination 1.

  3. Biopsy: If the fine needle aspiration is inconclusive or suggests cancer, a tissue biopsy may be recommended.

  4. Advanced imaging: For concerning lumps, additional tests may include:

    • Radiographs (X-rays)
    • Ultrasound
    • CT scan
    • In some cases, PET/CT scanning 2

Types of Common Lumps and Their Management

Benign Lumps

  • Lipomas: Soft, fatty tumors that are usually harmless
  • Sebaceous cysts: Blocked oil glands that may resolve on their own
  • Warts: Viral growths that are typically harmless
  • Histiocytomas: Usually self-resolving in young dogs

Concerning Lumps

  • Mast cell tumors: Common skin tumors that vary in behavior
  • Soft tissue sarcomas: Including injection-site sarcomas in cats
  • Mammary tumors: More common in unspayed females
  • Lymphoma: Can present as lumps in lymph nodes

Special Considerations for Cats

Cats are particularly prone to injection-site sarcomas (FISS), which can develop at sites of previous vaccinations or injections. These tumors:

  • Are aggressive and have a metastasis rate of 10-28%
  • Require aggressive surgical excision
  • May benefit from additional radiotherapy and/or immunotherapy 1

For prevention of FISS:

  • Avoid administration of irritating substances
  • Use non-adjuvanted, modified-live or recombinant vaccines when possible
  • Avoid injections in the interscapular region 1

Special Considerations for Dogs

In dogs, demodicosis (caused by Demodex mites) can sometimes present with nodular skin lesions. Diagnosis involves:

  • Deep skin scrapings (gold standard)
  • Trichograms or tape squeeze preparations in certain cases 3

When to Seek Immediate Veterinary Care

Seek immediate veterinary attention if the lump:

  • Appears suddenly and grows rapidly
  • Is ulcerated or bleeding
  • Seems painful to your pet
  • Is accompanied by other symptoms like lethargy, loss of appetite, or difficulty breathing

Follow-up Care

  • Monitor existing lumps for changes in size, shape, or appearance
  • Keep records of when lumps were discovered and any changes
  • Follow your veterinarian's recommendations for rechecks

Emotional Support

A cancer diagnosis can be emotionally challenging for pet owners. Many veterinary practices offer support for clients dealing with a pet's serious illness 4. Remember that early detection and treatment offer the best chance for successful outcomes.

Prevention

While not all lumps can be prevented, regular home examinations of your pet can help detect new growths early. Run your hands over your pet's body during regular petting sessions, feeling for any unusual bumps or swellings.

References

Research

Feline injection-site sarcoma: ABCD guidelines on prevention and management.

Journal of feline medicine and surgery, 2015

Research

PET-Computed Tomography in Veterinary Medicine.

The Veterinary clinics of North America. Small animal practice, 2016

Research

The owner of the pet with cancer.

The Veterinary clinics of North America. Small animal practice, 1990

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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