A small swelling under the fur can be hard to describe and easy to worry about. You are doing something useful by noticing it; you do not have to decide what it is.
Keep the spot comfortable and arrange a check rather than squeezing it for an answer. The location, speed of change and how your cat feels help the vet plan the assessment.
A new, growing or persistent lump on a cat deserves veterinary assessment. Record its position and changes without squeezing or puncturing it. Skin swellings can have different causes, and appearance alone cannot establish which one applies. Pain, discharge, rapid swelling or an unwell cat makes contact more urgent.
A swelling is a finding, not a diagnosis
Inflammation, infection and other processes can all produce a lump. Appearance cannot reliably separate them, and puncturing a swelling at home can add pain or injury. A selected cell or tissue sample may provide information needed before deciding whether to monitor, treat or plan removal.
Find it gently and describe it accurately
Notice where the lump sits and whether there is redness, hair loss, discharge or a nearby wound. Photograph it comfortably with a reference for size if possible. Do not hold a frightened cat down or repeatedly search through a painful coat just to produce a better record.
Write when it was first noticed and whether it seems to have changed. In a long coat, discovery can lag behind appearance. If the cat has had an injection, injury or surgery in that area, share the actual date and record rather than assuming that explains the lump.
Leave room for more than one possibility
Inflammation, infection and different types of growth can all produce a swelling. A cat who goes outside may have an injury history worth mentioning, but a location or texture is not enough to identify an abscess or a tumour. Do not try to drain a bump to see what comes out.
Mention appetite, weight, grooming, activity and any change in comfort when jumping or being touched. Bring previous sampling reports if available. A result from another lump, another cat or an earlier year cannot automatically explain the present finding.
Ask what a sample can answer
The vet may recommend collecting cells or tissue, or another test according to the examination. Ask what is being investigated and whether sedation or anaesthesia is needed for a comfortable, useful sample. Discuss what an inconclusive result would mean and what the next step could be.
If removal is considered, ask whether the planning depends on a diagnosis and whether laboratory examination of removed tissue is recommended. Understand the purpose of each step rather than choosing solely between ‘take it off’ and ‘leave it alone’. Costs and timing should be explained before proceeding.
Make follow-up a defined plan
Rapid growth, bleeding, substantial pain, a wound that does not heal or changes affecting eating or movement needs prompt contact. Breathing difficulty, collapse or sudden severe swelling calls for urgent help. Do not allow a generally unwell cat to wait simply because the lump has been present for some time.
If monitoring is recommended after assessment, agree on what to record and when to recheck. Keep photos, dimensions and results together. Ask who will explain laboratory findings and when to call if no result has arrived. Clear follow-up is more useful than repeatedly touching the lump and hoping it feels smaller.
A few good questions.
How should I record a new lump without repeatedly handling it?
Notice where the lump sits and whether there is redness, hair loss, discharge or a nearby wound. Photograph it comfortably with a reference for size if possible. Do not hold a frightened cat down or repeatedly search through a painful coat just to produce a better record.
Does a lump's appearance tell me whether it is serious?
Inflammation, infection and different types of growth can all produce a swelling. A cat who goes outside may have an injury history worth mentioning, but a location or texture is not enough to identify an abscess or a tumour. Do not try to drain a bump to see what comes out.
What can a sample from a lump help establish?
The vet may recommend collecting cells or tissue, or another test according to the examination. Ask what is being investigated and whether sedation or anaesthesia is needed for a comfortable, useful sample. Discuss what an inconclusive result would mean and what the next step could be.
Could I squeeze it if I think it is an abscess?
Please leave it intact and have the cat assessed. A possible abscess still needs an examination of the swelling and the cat’s overall condition, not home drainage.
What should I ask if the lump is going to be removed?
Ask whether diagnosis changes the surgical plan and whether removed tissue should be examined by a laboratory. Make sure results and the follow-up appointment have a clear route back to you.
Summary for readers & AI
A new lump on your cat: questions worth asking
A new, growing or persistent lump on a cat deserves veterinary assessment. Record its position and changes without squeezing or puncturing it. Skin swellings can have different causes, and appearance alone cannot establish which one applies. Pain, discharge, rapid swelling or an unwell cat makes contact more urgent.
General information, not an individual diagnosis or prescription. Sources are linked below.
Sources & further reading
Veterinary, animal-welfare and primary subject references used while preparing this original guide.
- Cornell: Feline skin diseases
- Merck Veterinary Manual: Diagnosing skin disease
- Cornell: Oncology and diagnostic assessment
A note about this read. Researched by the Dr. Paws editorial desk using the references linked above. General information, not a diagnosis or a personalised treatment plan. For a venue or organisation, confirm current details directly. Our editorial approach.
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