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.
From needle test to major resection, tier by tier
Watch, test or cut: a framework that is honest about all three
Usually gentle; the pathology report is the real finish line
Type, grade, margins and timing decide almost everything
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.
Send what your vet said and quoted. A veterinary surgeon reads it and comes back to you with what they can do and what it would cost, before you pay anything. A written second opinion is from $250.
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.
Send the case, hear back from a surgeon with what they can do and what it costs, and only pay if you go ahead.
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.
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.
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.