My 10-year-old dog has a lump around the size between a 10-cent/20-cent (Australian) coin. It’s round, soft to touch and when I touch it, it didn’t seem to cause him any discomfort or pain. It’s located on one of his hind flanks, on his thigh-ish area. Like if he sits down, the lump would be on the ground but it’s not near his anus. I’m not sure if I should take him to the vet..?

Answer by Shanika Winters Online vet

Hi Sheree and thanks for your question, with any lump you find on your pet I would advise that you take your dog to be seen by your vet.  I will try and explain in my answer some of the possible causes for the lump and how it can be monitored, treated or removed.

Why has my dog got a small soft lump?

Here are a few of the most common causes, ranging in seriousness;

Infected lumps

A small soft lump can be caused by an infection, reaction to a parasite/foreign body, swelling in response to an injury/allergy, a tumour or a combination of these.

Infection tends to lead to an area of reddened/hot (inflamed) skin, which may then swell up as it fills with fluid/puss.  An infected lump would usually appear over a few days, may be painful to the touch and might burst followed by crusting over.  An infected lump may be due to a skin infection, where a parasite has bitten, where a foreign body (e.g. a grass seed or thorn) has entered or is trying to exit or maybe on top of an existing lump.

Tick bite lumps

Reactions to a parasite/foreign body will also lead to inflamed skin but can occur over a much longer time scale of days to weeks.  Ticks are one of the most common parasitic causes of lumps.  On some occasions the lump that you see is actually the tick still attached to your pet’s skin. It could also be the reaction to a tick bite, looking like a small lump on your dog’s skin. 

Tick bite reactions are more likely to lead to a firm lump (granuloma).  Common foreign bodies that can cause a reactive lump in your pet’s skin include grass seeds and thorns.  A reaction to a foreign body may also be infected and/or painful.  Grass seeds and thorns are easy to come across on walks, depending on what season it is and where you tend to walk your dog.

They can also cause other issues of course. If you have concerns about a tick bite on your dog, you may want to read our article on Lyme disease.


Allergy or injury can cause a lump to develop quite soon after encountering e.g. a stinging nettle or having a tumble.  Allergic lumps can be single or multiple and can come down in time. The concern with an allergic reaction is if it affects the airways or circulation then this becomes an emergency situation requiring urgent veterinary attention.  A lump that occurs after an injury such as falling over or bumping into something at high speed is something an owner can usually link to the incident.


Tumours are abnormal growths that come about due to a mutation (change) in your pet’s cells, causing unregulated growth and multiplication of cells.  Tumours can be benign (not cancerous) or malignant (cancerous and likely to grow/spread).  The time scale of tumour development varies from slow growth to very fast and there are some tumours (mast cell tumours) that can vary in size due to the release of Histamine (reactive body chemical).

Should I take my dog to the vet?

Definitely take your dog to the vet if you find a lump. The urgency with which you need an appointment will depend on how long the lump has been present, how well your dog is and if the lump is changing.

Your vet will ask you a lot of questions such as:

  • How your dog is in general, eating, drinking and toileting?
  • How long has the lump been present?
  • Has the lump changed in shape, size, colour or texture?
  • Is the lump causing your dog any pain or affecting its normal bodily functions?

They will also ask about any changes in diet, environment, medications and general routine. So it is worth monitoring these things to be able to provide more insights when you visit.

The answers to all these questions, combined with a full clinical examination, will help your vet to work out what the lump could be and what steps should be taken.

What happens next?

In some cases, your vet may send your pet home with medication such as antibiotics. Particularly if the lump is thought to be an area of infection, or pain relief if it is thought to be a reaction to an injury.

If the lump is thought not to be harmful then your vet may ask you to monitor its size, shape, colour and texture on a weekly basis. You may ve invited to return for a check-up should there be any significant changes such as the lump doubling in size or changing colour.

Further Tests & Treatment

If however your vet is still unsure as to what has caused the lump then further tests may be advise, from a fine needle aspirate through to an excisional biopsy with or without x-rays.

Fine needle aspirate is when a needle is inserted into the lump (usually done in an awake pet) and some tissue sucked out into a syringe. This tissue can then be put onto a microscope slide or into a bottle of liquid for analysis. This will then enable your vet to work out what the lump is.

A biopsy is when a small piece or the entire lump is cut out (usually under a general anaesthetic) and is then sent for analysis to try and work out what the lump is.  If your vet finds other lumps or enlarged lymph nodes, which may be related to the original lump, then samples may need to be taken from these too.

X-rays of the affected area, chest and abdomen (tummy) may be performed to show how deep the lump goes and whether it has spread to other areas such as the lungs or liver.  The reason why the chest and abdomen are x-rayed is that these are common sites for the spread of malignant growths due to their very good circulation.

If the lump turns out to be cancerous then even after cutting out the lump your pet may need further therapy such as chemotherapy to treat/prevent the lump spreading or re-growing.

I hope that my answer helps to explain the importance of having a lump checked out by your vet, hopefully your dog’s lump is nothing sinister and your vet can confirm this. But due to the many possible causes of a lump it is always safer to get your dog looked at by your vet and then make a joint decision as how best to proceed.

Shanika Winters MRCVS (online vet)

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