What pet owners should know about lumps

Finding a mysterious lump on your pet can be a real worry – so it’s always worth a veterinary checkup to identify the cause.


Few things are capable of striking as much fear into our hearts as discovering a strange lump on our body. If we spot anything abnormal, most of us are keen to get our GP to check it out as soon as possible. The same is true for our pets. While it can be scary, it’s always worth getting lumps and bumps checked out by a vet.

What to look out for

As with humans, lumps on pets can vary greatly in size, shape and severity. Many dogs are prone to fatty tumours that are benign, and often appear as our pets age. However, there are a few things that are worth considering when speaking to a vet:

  • Did the lump appear suddenly?
  • Has it recently changed in shape, colour or size?
  • Has your pet been acting differently in terms of their appetite or energy levels?

To diagnose your pet, the vet may aspirate some cells from the lump using a needle and syringe and then examine them under a microscope. Occasionally, lumps may be sampled (a biopsy) to direct the vet to the appropriate therapy.

Different types of lump

Some lumps are not even lumps at all – for example, the tick, a common parasite that buries its mouthparts in the animal's skin head-first, with its exposed greyish body resembling a pea-sized lump. As well as causing local skin irritation, ticks can transmit harmful diseases and should be carefully removed with their mouthparts intact – otherwise a 'true' lump, known as a tick bite granuloma, may form at the site.

Serious lumps, such as mammary cancers, mast cell tumours and melanomas, usually require more involved treatment, with surgical removal, X-rays and laboratory tests helping to confirm identity and prognosis.

Causes of lumps in cats

Common feline lumps range from classic pus-filled cat bite abscesses to much smaller multifocal crusty scabs known as miliary dermatitis. As the name suggests, these feel like millet seeds in the coat, and are often a manifestation of an allergic reaction – for example, to flea bites.

Causes of lumps in dogs

There are many possible causes for lumps in dogs. For example, dogs and puppies might get lumps on their necks or jaws as a result of a skin reaction to an insect bite or a cyst in their salivary gland. Sometimes these lumps might seem to appear overnight.

Lipomas – soft, smooth, non-painful fatty lumps commonly found under the skin over the ribcage of more mature dogs – rarely require removal; in fact, most non-serious growths are usually purely cosmetic, with surgery only required if they causing discomfort, suddenly grow rapidly, interfere with bodily functions (for example, affect the dog’s gait), ulcerate, repeatedly get infected or act as a persistent focus for your pet to lick and chew. It is important to appreciate that while a vet may have a good idea about the nature of a lump, they cannot be 100% certain of what a lump is just by feeling it.

One lump commonly appearing in the warmer months is the foreign body reaction caused by a grass seed stuck between your dog's toes, a painful swollen area that requires prompt veterinary help. Early intervention will often prevent serious, painful or even life-threatening growths from developing further, so the golden rule for any lump (on cats and rabbits, as well as on dogs) is: get it checked out!

Causes of lumps in rabbits

Rabbits are prone to dental issues and a lump can often be a sign of problems like abscesses. If you feel lumps on your rabbit’s head that are on one side only, it’s best to consult a vet to determine the appropriate course of treatment. This could include complete surgical removal of the abscess, antibiotics or flushing the abscess with medication. It’s particularly important to keep an eye on any swelling that changes the size and shape of the lump.

Lumps on older pets

As with older people, elderly pets are more likely to have warts and small growths of the skin that may appear unsightly. These are usually benign – unlikely to spread or cause any harm – but do still require close monitoring. Always consult your vet if you have any concerns about your pet.


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