Help! My Dog Has A Lump

Updated October 18th, 2020

If you’re a dog owner, it’s almost inevitable that you’ll find a lump at some point. Dogs get lots of lumps and bumps, especially as they get older. How do you tell which ones are more serious?

Later I’ll show you a large gallery of pictures and descriptions of the most common lumps of dogs.

Which Dog Lumps Need Removal?

Some of the ways you can identify a dangerous lump are:

  1. Speed: if a lump looks bigger in only a month it’s growing rapidly
  2. Shape: smooth, round lumps whether on or under the skin are usually worse
  3. Appearance: black, pink or ulcerated surfaces are more worrying
  4. Feel: subcutaneous lumps should move easily between the skin and the body
  5. Position: watch out for lumps on the head, legs and tail (I’ll explain later)
dog skin tumour
Typical appearance of many skin lumps such as mast cell tumours or histiocytomas. Slide shows typical FNA appearance

The only way to know for sure is to take a biopsy. That’s where we take a small piece and get it examined. A biopsy does two important things:

  1. It tells us whether the lump is dangerous or not
  2. It helps us decide how big a surgical margin we need

Common Lumps Of Dogs

So the earlier we see a lump, the more options we have. If you’re afraid of bad news, don’t be; despite the horror stories, a biopsy or surgery isn’t always needed, and most lumps are benign. Your vet can even identify most lumps straight away. Here’s what they are and how we can tell.

See also: Common Mouth Lumps Of Dogs and A Lump Below The Eye

Lipoma or Fatty Growth

What they are: the classic lump under the skin of older dogs. It’s actually a benign tumour of fat cells, and should grow so slowly it takes 6 months to see any change. Most often found on the chest or abdomen.

How we tell: a fine needle aspiration (FNA) gives a clear answer. Never assume a lump is a lipoma unless your vet has done this first.

Treatment: none, usually. Lipomas need removal only when they occur in difficult positions like the legs or armpits. I also take them off younger dogs if they will get huge in a normal lifespan.

See pictures of lipomas and similar lumps under the skin here.

Soft Tissue Sarcoma

dog sarcoma tumour

What they are: fast-growing, locally invasive tumours of connective tissue, common in large breeds.

How we tell: biopsy is necessary. Sarcomas feel just like lipomas and are often mistaken for these if a needle aspirate isn’t done. A clue in this case is the position; lipomas are rarely on the legs.

Treatment: prompt, careful resection with a wide margin. The picture shows a fibrosarcoma on a leg with a standard 2cm margin. I hope you can see why the earlier we check these lumps, the better.

Sebaceous Cyst

dog sebaceous cyst

What they are: a blocked sebaceous gland causes a buildup of hard, cystic material attached to and under the skin. Note in the picture how the skin surface is reasonably normal-looking.

How we tell: a fine needle aspiration is necessary to distinguish from other masses.

Treatment: none, usually. Most sebaceous cysts never cause problems though occasionally they will burst.

Sebaceous Adenoma

sebaceous adenoma dog

What they are: a benign tumour of sebaceous glands, often wrongly called a wart. Very common in Poodles, Maltese, Bichons and their crosses. This one is on an ear.

How we tell: biopsy is necessary, however, the classic appearance and slow growth make us near-certain just by looking.

small sebaceous adenoma

Treatment: most sebaceous adenomas never cause problems, but any that are ulcerated or being licked need removal.

Here’s another sebaceous adenoma, showing what they look like when small.

Papilloma or Wart

canine papilloma

What they are: multiple small lumps often on the face and head. Just like in humans, warts are caused by a papillomavirus; young dogs that get them go to dog parks or day care.

How we tell: biopsy is necessary, however, their classic feathery appearance is hard to mistake.

dog ear warts

Treatment: none. Although they can look terrible, warts should go away by themselves after a few months.

Here are a group of warts on the ear and die of the head. See also: pictures of dog warts in the mouth.

Skin Tag

skin tag dog

Skin tags are very similar to warts except they are usually smooth, long and narrow. They grow extremely slowly and pose no threat. The one pictured is quite large, and unusual in being pigmented, not pink.

Skin tags may start with anything that causes skin damage, such as papilloma virus, injuries, abrasion or infection.

Mast Cell Tumour

What they are: fast-growing, pink button-like lumps which can be well-behaved or very aggressive. MCTs have a reputation for recurring following incomplete removal.

How we tell: your vet can usually do it via fine needle aspiration (see earlier) but sometimes a biopsy is required.

Treatment: should always be removed with a margin depending on the ‘grade’ or severity.

dog nasal infection

What they are: fast-growing, raised red lumps sometimes with a surface crust. Granulomas look like aggressive tumours but are actually a solid form of bacterial infection.

How we tell: sometimes a biopsy is required but we are often sure enough just from inspection.

Treatment: antibiotics, not surgery.


canine cutaneous melanoma

What they are: slow-growing, dark lumps not caused by sunlight. Skin melanomas of dogs need removal, but they are a lot less malignant than human ones and shouldn’t make you lose sleep.

How we tell: there isn’t much else that’s black.

Treatment: removal. Baxter (pictured) gets repeated melanomas. After removing the first few we have been watching his latest set for signs of growth.

Haemangioma and Squamous Cell Carcinoma

dog haemangioma lump

What they are: two tumours caused by ultraviolet damage from sun exposure, common in Adelaide on unpigmented areas of sunbathing dogs. You can see that the one on the dog’s leg has started on a pink area.

How we tell: haemangiomas are red, berry-like masses that bleed easily; squamous cell carcinomas are raised, crusty sores.

Treatment: removal. SCC, in particular, can spread to lymph nodes and cause death if left too long.

Perianal Adenoma

dog anal lump

What they are: benign tumours found especially around the anus or the underside of the tail

How we tell: position and slow growth, plus their strong association with entire males or late desexing (though we occasionally also see them in females and neutered males too)

Treatment: removal, best done as soon as possible given the tricky location. This one is bigger than ideal.

Follicular Cysts

dog follicular cysts

Follicular cysts are rare skin lumps caused by dilation and rupture of hair follicles. Although they may look like tumours, they are benign and usually easy for your vet to remove under anaesthetic.

A Mystery Lump

floppy benign lump

This one we also see frequently. It’s very soft and squishy, has an irregular outline and is extremely slow growing. I have never needed to have one removed or tested.

Phew! There are lots of rarer lumps on and under the skin but I hope you’ll never see them. For example, the other one at the start is a Sertoli Cell Tumour caused by a retained testicle. No dog should suffer from any of even the worst of these tumours if you get them checked in time.

dog cutaneous lymphoma
Epitheliotropic lymphoma

Even rarer is the last one. You can read more about epitheliotropic lymphoma here.

Have something to add? Comments are welcome below and will appear within 24 hours.
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These help topics are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story! The information provided here is not intended to be used as a substitute for going to the vet. If your pet is unwell, please seek veterinary attention.

Note: I won’t publish comments of a similar nature to ones that are already present. Therefore, it’s a good idea to check the others first. Please remember that only a visit to a vet can truly tell the identity and seriousness of a lump.


173 Replies to “Help! My Dog Has A Lump”

  1. I have a toy size (5 pounds) 4 year old Yorkie and she is not spayed. I’ve noticed a lump that gradually increased in size within the past few months. It is located on the right side of her lower abdomen right above her private part and I would say right were her breast starts. When I touch it, it doesnt seem to bother her at all. It moves very easily. She is acting and eating normally and doesn’t seem to be bother more than I am about it. What do you think this is? Thank you.

  2. I have a three years black pug and recently we noticed a white ( with some redness) bump on this tail .
    I do not know what is it or what caused it??

    1. Hi Matthew. Pugs commonly get infected papules and pustules in the skin that can get quite large. Therefore, I would see a vet for this one as it’s likely to get worse.

  3. hi, my dog (4 yr old female havanese, turning 5 in Jan ’21) has a hard bump under the skin that is not visible and doesn’t seem to bother her, you can feel it but i cant tell if you can move it or not. any ideas on what it is? its right between where she had sutures and a penrose drain inserted, she only recently just got attacked about 1 1/2 months ago, so im wondering what it could be (it developed about the time she got the sutures out, which was 9/3/20) i posted this 9/22/20

    1. Hi Elizabeth. Given what you say, it’s most likely to be an area of scar tissue from the dog attack. Just once I have seen a small piece of Penrose drain break off when it was removed so that’s a vague possibility as well. Your vet should be able to give you a straight answer.

      1. ok, thank you for the answer! i’ll ask my vet next time we go, my dog has her vaccines due next month so i’ll ask then

  4. Hi! I just noticed today a lump on my dog. She’s a 7 year old, Jack Russell Terrier who is not spayed. She just came out of heat recently The, and has never been bred.

    The lump is located on her chest, in the center, just above where her belly button would be (situated just above the ending of her rib cage). It’s hard, more flat than round, looks pink-ish like its inflamed, and has a scab on in the center. It’s a little less than 1.27 cm in diameter. It doesnt seem to be painful. It also moves easily, and just seems to be only in the epidermis layer of skin.

    Any ideas? Thanks so much!

    1. Hi Erynn. The presence of a scab makes it sound like a granuloma. However, in this position, any lump could have a scab just from abrasion with the ground or floor, or from licking. A mammary tumour is possible, but unlikely as these are usually distinctly underneath the skin not in or on it.

  5. My 12 year old female terrier mix has growth on her female parts. It is red and looks similar to the Perianal adenoma pictured above. She has not been spayed and has not been bred. It appeared suddenly. She licks at it. It is almost round in shape.

    1. Hi Ellen. Regardless of its identity, once a lump starts being licked it needs removal due to the ulceration or dermatitis. This also commonly happens with sebaceous adenomas on the legs and feet.

  6. I have a 10 yr old shitzu that has a wart like growth on his leg. Over the last 5 yrs it has doubled in growth and has a stalk. The vet won’t biopsy it thinking it might get infected. She wants to remove but wouldn’t know how far the margins should be. This dog has skin issues and allergies.

    1. Hi Teri. The decision on how wide to make the margins will depend on many factors, but especially the local availability of skin which is often limited on the leg. Therefore, the most important thing is not the size of the margin, but that the margins get checked by histopathology afterwards. Then, if tumour still remains it’s always possible to either go back or refer to a surgical specialist for wide resection and reconstruction. However in your case, a lump that has been present for five years is probably relatively benign and can be completely removed in most cases with a smaller than average margin.

  7. We have a boxer that we rescued after our neighbors moved and left him. He is about 10years old. He has a black soft lump on his left rear hip that is the size of small rubber ball. We don’t know much about his background except that our neighbors said they rescued him from abuse about 8 years ago and he was 2 then. It doesn’t appear to hurt and it bounces, for lack of a better term. His back legs are weak and his hips are narrow and his back legs almost touch when he stands. He never lets me out of his sight and follows me everywhere. Any ideas? Thanks

    1. Hi Terri. What a story. To rescue a dog and then abandon him again! No wonder he won’t let you out of his sight. Boxers commonly get mast cell tumours or sarcomas that sound like this lump, but only a vet can say for sure. It sounds like he might have arthritis as well. All of this is probably fixable.

      1. Thanks for the information! Could you please tell me why fleas seem to congregate around his rear? He has them almost no where else. We bathe him, use flea treatment, vacuum, and keep his bed clean, but they love to attach themselves to his butt.

      2. I’m not at all certain but it could be that you are using a flea product on the shoulders, so that the lowest concentration would be towards the rear. Have you tried one of the tablet forms?

  8. I have a poodle mix at 34 pounds and she has a big bump on her left side by her belly and it looks like its going to pop. Should i just leave it alone until i get to her doctor?

    1. Hi Kathy. Yes – definitely leave it alone. There’s almost nothing you can do that would make a lump better before the vet has a look.

    2. Hi. My 13 year old staffy has what looks like the long black skin tag as shown in this article, however there is also a soft move able lump underneath this. Last check up vet suggested it looks/feels like a lipoma and it has been very slowly growing. From the description would you say this diagnosis seems to fit?

      1. Hi Tracy. Yes that sounds to be the best explanation, and as I say in the article a lipoma can usually be identified by needle aspiration.

  9. I adopted a Great Pyrenees two years ago. The rescue estimated she was 8. She was spayed at that older age. She has been experiencing fecal incontinence that I thought was just due to age and arthritis. However, we recently had her shaved and there is a large lump just where her tail starts. I am wondering if that is effecting her nerves that control bowels.

    1. Hi Carla. Does it look anything like the Perianal adenoma listed above? These can also occur on the tail base, and they do interfere with defecations at times. Definitely worth getting a vet to take a look.

      1. Hi, I have a bloodhound that is around 7 years old he is a male and we have had ongoing problems with ear infections but no matter what they give us it always comes back. I just seen he has three big black growths under his neck and it’s a size of a big raisin (all black). He has been itching a lot and seems to be sleepy more even though a bloodhound is lazy. Please help me understand what is going on very concerned!! Thank you

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