You cannot tell what a lump is by feeling it. Soft, movable and slow growing is reassuring but not diagnostic, and some serious tumours feel exactly like harmless fatty lumps. A quick sample taken with a fine needle usually gives an answer in a single visit, which is why testing beats watching and waiting.
The most common thing owners get told, and why it is wrong
Almost everyone has heard some version of “if it is soft and it moves, it is just a fatty lump”. It is a comforting rule and it is genuinely unreliable.
Lipomas, the benign fatty masses that most dogs eventually develop, are indeed usually soft and movable. The problem is that at least one significant tumour type, the soft tissue sarcoma, frequently feels identical, and mast cell tumours are notorious for imitating almost anything, including a small soft lump that seems to change size from week to week.
So the texture test cannot separate them, and neither can size, location or how long it has been there. What separates them is looking at the cells.
Why this comes up in late summer
Two practical reasons. Coats are shorter or have been clipped, so hands find things that were buried in winter fur. And grooming, swimming and more handling generally mean owners are running their hands over their pets more often than they do in February.
Willoughby and the newer Langley neighbourhoods also have a lot of dogs who arrived as puppies four to eight years ago, and that is exactly the age band where lumps start appearing in numbers.
What is worth acting on quickly
Any new lump deserves examining, but some features move it up the queue:
- Growing noticeably, especially over weeks rather than months
- Changing shape, firmness or colour
- Ulcerated, bleeding, weeping or scabbed over
- Red, hot or obviously painful, or your pet keeps licking or chewing at it
- Firmly attached to underlying tissue rather than sliding freely
- Anywhere on the face, mouth, toes, nail bed or around the anus
- Appearing alongside weight loss, reduced appetite or lethargy
- Multiple new lumps arriving together
- Any lump on a cat, which deserves a lower threshold than in dogs
That last point matters. Cats develop fewer benign skin lumps than dogs do, so the odds are less favourable, and a firm lump in the mammary chain or at an injection site is taken seriously. A cat with a new lump should be seen rather than monitored.
The test that answers most of this
A fine needle aspirate is quick, usually well tolerated in a conscious animal, and often gives an answer the same day or within a few days. A small needle is inserted into the lump, cells are drawn into it, and those cells are examined under the microscope. Most pets object to it less than to a vaccination.
It is not perfect. Some lumps do not shed cells readily, some results come back inconclusive, and some need a biopsy of a tissue sample instead to give a definitive answer and a grade. But as a first step it resolves a large proportion of cases and costs the animal very little.
This is the reason the profession pushes back on watch and wait. Waiting has a cost that only becomes visible in hindsight, because a mass that was small and cleanly removable in August can be considerably harder to deal with by Christmas. Testing runs through our diagnostic services, with the findings discussed in a medical consultation.
What the common answers look like
Lipomas are benign fatty masses, common in middle-aged and older dogs and particularly in overweight ones. Most are simply monitored, and removal is considered when one sits somewhere that interferes with movement, in an armpit or between the legs, or when it grows large enough to be a nuisance.
Sebaceous cysts and skin tags are common, benign and usually left alone unless they become inflamed or catch on things.
Histiocytomas are a benign lump seen mainly in young dogs, often appearing quickly as a small raised button on the head, ears or limbs, and they frequently resolve on their own over a couple of months.
Mast cell tumours are the great imitator and the reason the feel test fails. They vary enormously in behaviour, and grading them guides everything that follows.
Soft tissue sarcomas often feel like lipomas but sit within or under the tissue rather than freely in the fat, and they need proper surgical planning because the margins matter.
Abscesses are a separate category and are common after a cat fight puncture: hot, painful, rapidly appearing swellings that need treatment rather than testing. Those are handled through our urgent care service.
Planning matters more than speed
If a mass does need removing, the single most important factor is the plan. A tumour removed with adequate margins the first time has a very different outlook from one removed narrowly and then needing a second, larger operation on scarred tissue.
That is why the aspirate happens before the surgery rather than after. Knowing what a mass is determines how much tissue needs taking, whether imaging is needed first to check elsewhere, and whether referral is appropriate. Surgery sits with our surgical services team, and removed tissue is normally sent for laboratory analysis even when everyone expects a benign result.
Keeping track at home
For a pet with several lumps, memory is not good enough. Draw a rough body map, or use your phone: photograph each lump beside a coin or a ruler for scale, note the date and the location, and repeat every couple of months. Measuring in millimetres beats “about the same, I think”.
Check your pet properly once a month, ideally when they are relaxed. Work systematically with flat hands: head and muzzle, ears, neck and throat, along the back, chest and belly, armpits and groin, down each leg to the toes and nail beds, and the tail and back end. Feel for anything raised, firm or asymmetrical, and note what you find.
Bring the photographs to your appointment. A documented rate of growth genuinely changes clinical decisions, and it is information nobody but you can provide. Routine checks through our wellness services are where new lumps are most often found first, and our guide to what Willoughby and Latimer owners notice first in aging pets covers the other changes worth tracking at the same time.
Frequently asked questions
Can my vet tell what a lump is by feeling it?
No, and no experienced veterinarian will claim otherwise. Soft, movable lumps are often benign fatty masses, but soft tissue sarcomas frequently feel the same and mast cell tumours can imitate almost anything. Texture, size and duration are all unreliable. Looking at the cells is what gives an answer, and that usually takes one visit.
Is a fine needle aspirate painful?
Most pets tolerate it well and object less than they do to a vaccination. A small needle is inserted into the lump and cells are drawn into it, usually with the animal conscious and without sedation. Some lumps do not yield enough cells, in which case a tissue biopsy may be recommended to give a definitive answer.
My dog has lots of lumps. Do they all need testing?
Not necessarily all at once, but each new one should be assessed, and previously tested lumps should be re-checked if they change. Having many benign fatty masses does not protect a dog from developing something different, and the assumption that a new lump is “another one of those” is a common way a significant mass gets missed.
Should I wait and see if it goes away?
Generally no. A small number of lumps, notably histiocytomas in young dogs, do resolve on their own, but you cannot identify those by looking. Waiting costs nothing when a lump turns out to be benign and costs a great deal when it does not, because a mass that was small and cleanly removable can become much harder to treat.
Are lumps on cats more serious than on dogs?
The odds are less favourable. Cats develop fewer benign skin lumps than dogs, so a new mass in a cat is statistically more likely to matter, and lumps in the mammary chain or at injection sites are taken particularly seriously. Any new lump on a cat should be examined rather than monitored at home.
How should I monitor a lump my vet is happy to leave?
Photograph it next to a coin or ruler for scale, record the date and location, and measure it in millimetres every couple of months rather than relying on memory. Contact the clinic sooner if it grows, changes shape or firmness, becomes red, painful or ulcerated, or if your pet starts licking at it.