Skip to content

A guide to lumps and bumps on cats

Have you noticed a lump when stroking your cat? Whilst it may be harmless, it's always important to consult your veterinarian whenever you detect any changes in your cat’s health. That's because painful infections, inflammatory lesions and cancerous tumours are always a possibility, and all require veterinary intervention – the sooner you act, the better!

Here's a helpful guide to some common causes of lumps and bumps on your cat, and what you should do about them.

What are common causes of lumps in cats?

Lumps in or on a cat’s skin will typically be caused by the following:

  1. Trauma: Lumps can result from trauma-related injuries, which may be sustained in an accident, such as being struck by a car or attacked by a dog (or something less dramatic but equally as painful). Hernias can occur due to damage or weakness in the muscle wall and require urgent veterinary examination and usually surgical repair.
  2. Parasites: The bites from parasites, such as fleas and ticks, can cause a reaction resulting in small lumps on your cat. You may even feel a tick that has attached to your cat’s skin. Paralysis ticks are common in certain areas of Australia and the toxin they inject into animals can be fatal without urgent, intensive vet care, even after the tick has been removed. Speak to your vet about suitable parasite prevention for your cat and check your pets daily. Never use a dog tick prevention on a cat as this is dangerous and can be potentially fatal.
  3. Inflammation: Allergic (hypersensitivity) reactions, such as from an insect bite or sting, can cause small lumps in the skin (including welts and hives). Eosinophilic granuloma complex is a common group of inflammatory skin problems seen in cats, and is thought to can be initiated by several factors, including allergic responses. Eosinophilic granuloma complex can cause lumps in your cat’s skin, but is often seen as ulcers on the cat’s lip, or as ulcers or swellings elsewhere on the body. Foreign bodies (e.g. a grass seed) in or under the skin can also cause inflammation (and infection) resulting in a lump.
  4. Infection: Bacterial or fungal infections can cause lumps in or under the skin. Abscesses are commonly seen in cats, and can be caused by a bacterial infection from a cat bite or scratch. Cats who are allowed to freely roam outdoors are most at risk of cat fights, and the resulting bites and scratches and infections. Abscesses are painful, pus-filled swellings that can be associated with fever, lack of appetite, and depression, and need immediate veterinary attention.
  5. Tumours: Tumours occur when the body’s cells lose their ability to regulate themselves, and can arise anywhere on your cat’s body. Benign tumours such as lipomas (fatty lumps) are generally considered harmless unless they grow so big to impact on your cat’s mobility or comfort. Malignant lumps include those tumours that can spread, such as mammary lumps (breast cancers). Veterinary advice should be sought promptly for any lump to determine what it is and what needs to be done.

How does my vet determine what the lump is?

After taking a careful history from you about the lump and your cat’s general health, your vet will perform a thorough physical exam on your cat and inspect the lump. Some lumps, such as abscesses, may be able to be diagnosed by examination alone, but others will require further testing.

The most commonly performed initial test on lumps is a fine needle aspirate or FNA. For this test your vet will insert a needle into the lump to obtain a sample of cells that are then transferred onto a microscope slide. The slide is then stained with special dyes to help show the cells clearly under a microscope. In some instances, a diagnosis can be made right away, or your vet may send the slide to a specialist veterinary pathologist for diagnosis.

For other lumps, a tissue biopsy will be required. This is a short procedure performed under a general anaesthetic. The tissue sample is then sent to the lab for testing by a specialist veterinary pathologist. Other diagnostic tests for skin conditions include skin scrapes or hair plucks (to get a sample of skin cells or fur) and bacterial or fungal cultures (to determine if there is an infection and what the cause is).

Treatment of lumps

The treatment recommended by your veterinarian will depend on the cause of your cat’s lump. Treatments which may be recommended for the common causes of lumps discussed above can include surgical removal, medicated ointments, antibiotics, antifungal medication and anti-inflammatory drugs, but this will depend on the specific lump and cause. In some cases, your vet may advise a lump can be carefully monitored to see if it grows or changes. Veterinary oncologists are able to provide treatment for animals living with cancer.

Can I reduce the risk of my cat developing certain lumps or bumps?

Keeping your cat safely indoors with access to a suitable outdoor enclosure will reduce the risk of getting cat fight abscesses, or injury from accidents.

Having your cat desexed before puberty (before four months of age) has many benefits, including decreasing the risk of mammary cancer in your female cat.

Get into a routine whilst your cat is young of regularly brushing and gently checking your pet’s skin. Knowing what is normal for your cat, you will be best able to identify anything that feels abnormal and identify any problems early. The earlier you identify a lump and get it checked by your vet, the better. It’s a great help to vets when you can tell them when you notice the lump or bump, whether it is growing and if this growth is rapid or slow and if your cat is showing other signs of feeling unwell.

Identifying lumps and bumps early

Many of us enjoy spending time relaxing and bonding with our cats, which can be a purr-fect opportunity to check their skin for any lumps and bumps. If you find any unusual lumps or bumps on your cat, you should consider immediately booking them into the vet for a checkup.

RSPCA Pet Insurance can help by covering part of your vet costs for eligible accidental injury and illness. Find out more about what levels of cover are available to help support your pet’s needs. If you’re with RSPCA Pet Insurance, a portion of first-year premiums will go towards supporting the valuable work of the RSPCA.

Dr Catherine Tiplady bio image

Dr Catherine Tiplady

Dr Catherine Tiplady studied veterinary science at the University of Queensland. After graduation, Dr Catherine worked in veterinary practice whilst undertaking postgraduate research in Animal Welfare, gaining additional degrees in Bachelor of Applied Science (Animal Studies) (Hons 1) and a PhD. Dr Catherine has published widely in peer reviewed scientific journals and has also authored a book, ‘Animal Abuse: Helping Animals and People’. Currently working in small animal practice, Dr Catherine also has her own business performing gentle in-home pet euthanasia and provides veterinary care and desexing services for animal welfare charities. Dr Catherine brings her passion for animal welfare, love of writing and scientific training together to contribute quality content to RSPCA Pet Insurance’s Pet Care blog.