Skin Lumps & Tumors
The appearance of a skin lump can't tell you if it's benign or malignant — only a vet needle biopsy can. The "Pea Rule" is a practical guide for when to get one checked.
What to Do If You Find a Lump
For a lump found on a cat or dog, appearance, firmness, or whether it hurts can't tell you if it's benign or malignant — the only accurate way to know is for a vet to take a needle sample (cytology) or biopsy. Many owners delay a checkup because a lump "doesn't look serious," which is the most common reason for delayed tumor treatment.
The Pea Rule
A simple guideline advocated by American veterinary oncologist Dr. Sue Ettinger: once a skin lump reaches about 1 cm (pea-sized) and has been present for more than 1 month, it should be needle-checked — you don't need to wait for it to grow bigger or for other symptoms to appear. Early detection and early diagnosis are the most important factors for improving treatment success rates.
Building a Home Self-Check Habit
It's a good idea to develop a regular habit (for example, every time you groom your pet) of feeling over your cat or dog's whole body, noting any new lumps or changes in the size of existing ones. Recording when a lump appeared, its location, and its size gives your vet more complete information at your next visit.
Want to track this over time? Try Chronlo
A chronic-care app for cats and dogs: daily logs, trend charts, blood test OCR, and medication reminders — all your pet's health data in one place.
Sources:
- Dr. Sue Ettinger（腫瘤科獸醫師）倡導的 Pea Rule / See Something, Do Something 準則
This site is for general reference only and is not a substitute for veterinary diagnosis. If your cat shows unusual signs, please see a vet promptly.