Lumps, masses and tumour surgery: test first, then decide

Every grey muzzled dog collects lumps, and most are harmless. The whole game is knowing which ones are not, before choosing between watch and wait, a simple removal, and proper cancer surgery. The single most useful sentence on this page: lumps get tested, not guessed.

EMReviewed by Eben Martin, Veterinary Surgeon · Updated August 2026
Simple removal
$500 to $2,000
Small skin lumps at a general practice
Cancer surgery
$2,000 to $8,000+
Wide margins, reconstruction or internal masses
The rule
Test, not guess
A needle sample costs little and changes everything

In this guide

Why guessing fails

Experienced vets are decent at guessing lumps, and still get meaningfully wrong often enough that guessing is not a plan. A mast cell tumour can look and feel exactly like a fatty lipoma. The fix costs comparatively little: a fine needle aspirate, a few cells under a microscope, and suddenly you are making decisions about a named thing instead of a mystery. Insist on it before any removal, and be suspicious of a plan that skips it.

Margins: why cancer surgery costs more

Removing a benign lump means taking the lump. Removing a malignant one properly means taking a margin of healthy tissue around and beneath it, because tumour cells you cannot see extend past the edges you can. That is the difference between a $700 lumpectomy and a $4,000 oncological resection, and it is also the difference between done once and done properly versus a second, harder surgery through scar tissue when it grows back. If the cytology says malignant, the margins conversation is the whole ballgame.

Told a lump needs removing?

The cytology, the margins plan and the quote reviewed independently. From $250.

Ask about your case

Common questions

The vet says it is probably just a lipoma. Fine to leave?

Probably is doing a lot of work in that sentence. A needle sample turns probably into confirmed for a modest cost, and confirmed lipomas can usually be left unless they impede movement. It is the cheapest peace of mind in veterinary medicine.

How urgent is a lump that is growing?

Growth, ulceration, sudden appearance, or a lump that changes size day to day all move testing from sometime to this fortnight. Fast growing masses are also the ones where waiting narrows the surgical options.

My cat has a lump where injections are given.

Take that one seriously and promptly. Cats can develop injection site sarcomas, which are locally aggressive and need wide, well planned first surgery. The standard advice: a vaccine site lump persisting past three months, bigger than two centimetres, or growing after a month, gets investigated.

Found a lump, or holding a removal quote?

An independent written opinion on the diagnosis, the technique and the quote. From $250.