Urgent — same day vet contact
Within 1–2 weeks
New skin lump on a cat
Any new skin lump in a cat needs a vet visit — feline lumps are more often malignant than dog lumps; do not wait and watch.
Recognise the signs
- New lump anywhere
- Hot, swollen, painful — likely abscess (urgent)
- Firm, persistent, possibly growing — needs investigation
First aid steps
- Photograph and measure.
- Phone the vet for an appointment within 1–2 weeks; sooner for hot/painful (abscess), bleeding, or rapidly growing.
Do NOT
- Do not assume it's just a fat lump — cats develop fewer lipomas and more cancers proportionally.
- Do not pop an abscess at home.
When to phone the vet immediately
- Hot, painful, or rapidly growing lump
- Cat off food, lethargic
Common causes
- Abscess from bite wound (commonest, especially outdoor cats)
- Mammary tumour (highly likely malignant in cats)
- Fibrosarcoma (sometimes vaccine-associated)
- Mast cell tumour
- Cyst, lipoma (less common)
What the vet will need to know
- When first noticed
- Site (especially mammary chain in females, vaccine sites)
- Vaccination history (vaccine-associated sarcoma)
Aftercare
- Fine-needle aspirate or biopsy.
- Surgery often recommended for any persistent lump in cats.
- Mammary lumps in entire females especially urgent.
Prevention
- Spay female cats young (drastically reduces mammary tumour risk).
- Routine grooming with body checks.
- Annual vet exams.
Frequently asked questions
Why are cat lumps more often cancer than dog lumps?
Cats develop fewer benign skin growths proportionally. The 'wait and see' approach acceptable for some dog lumps is risky in cats.
What's vaccine-associated sarcoma?
A rare but serious tumour at vaccine sites. Modern vaccines and protocols minimise risk; any persistent lump at a vaccine site should be checked promptly.
Will my cat need surgery?
Most persistent feline lumps are removed and biopsied. Early removal often gives the best outcome.