You rub the rib cage — new grape under skin — slides under fingers. Lipoma — benign fat tumor — top guess in middle-aged chunky Labs. "Soft and movable" alone does not guarantee benign — mast cell tumors masquerade — aspirate every new lump.
Key points at a glance
- New lump any size — vet FNA or biopsy — don't watch six months.
- Lipoma — soft, freely movable, slow grow, under skin — common on trunk.
- Fast grow, fixed, ulcerated — urgent — not lipoma profile.
- Location on leg or armpit — harder to ignore — remove if growing.
- Obese dogs — multiple lipomas — each still documented.
Lipoma typical features
| Feature | Lipoma | Suspicious |
|---|---|---|
| Feel | Soft, doughy | Firm or mixed |
| Move | Slides under skin | Fixed to tissue |
| Growth | Slow years | Weeks |
| Surface skin | Normal | Red, ulcer |
| Pain | Non-painful | Painful |
Only cytology confirms — feel is screening.
Fine needle aspirate — what happens
Quick needle sample — cells on slide — lipocytes vs abnormal — minutes to days lab.
Non-diagnostic sample — biopsy — worth cost.
When to remove lipoma
- Interferes walking — armpit, elbow
- Rapid enlargement
- Owner can't monitor — size of orange
- Cosmetic — low priority medically unless massive
Surgery easier small — general anesthesia risk weigh age.
Not lipoma — common mimics
- Sebaceous adenoma — wart-like
- Mast cell tumor — may shrink and swell
- Soft tissue sarcoma — deceptively soft sometimes
- Abscess — hot, painful, fast
- Hives — come and go day
Lipomas and weight
Fat dogs grow more lipomas — weight loss doesn't shrink existing much — prevention unproven.
Record keeping
Photo with ruler monthly — map locations — vet compares.
The bottom line
A soft movable lump on your dog's skin is often lipoma but never certainly benign by touch alone — schedule fine needle aspirate for every new mass. Slow fatty growth on the trunk in older dogs fits lipoma; fast change, fixation, or ulceration does not. Map and measure; let cytology decide, not internet reassurance.
This article is for general education only and does not replace advice from a licensed veterinarian.