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Bumps and Tumors on Dog Lips: Our Vet Explains [With Pics]

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inspection of a dog's lips

This article was updated on August 14th, 2023

If you’ve noticed a new lump, bump, tumor or growth on your dog’s lips, you’re likely jumping to all sorts of conclusions about what it could be. As a vet working in a busy clinic, I see lip lumps and bumps on a weekly basis, and the owners are inevitably worried about what might be going on.

A new bump or growth on a lip can be a range of things, each requiring a different treatment. It is important to get a diagnosis. In this article, we will discuss the top causes & what to do.

Is a new bump on a dog’s lips a reason for concern?

Any new lump or bump on a lip, especially one that is rapidly growing or has been present for over two weeks, is something we should take seriously. Lumps or bumps on older dogs, or on dogs who have had cancer in the past, should be assessed promptly.

On the other hand, if your dog is young, the chances of a new lip lump being benign are very high. Regardless, having the lump checked over by a vet is sensible, so we can ensure we know what we are dealing with and get your pooch started on the right treatment plan.

The lumps we worry about most are those that enlarge rapidly, ulcerate on the surface and bleed. We tend to be less concerned about those growths that are slowly evolving and those that are attached by ‘stalks.’ Similarly, skin tags and warts have a specific ‘fleshy’ appearance, when compared to more sinister lesions.

What the color of a lip bump or spot can tell you

A bump on a dog’s lip can be an array of different things, and sometimes the color of the lump will provide some clues.

1. Pink spot on dog’s lip

warts on a dog's lips near the mouth
Example pink growth on a dog’s lip

A pink or flesh-colored spot, especially those that look like little ‘brains,’ commonly appear on older dogs. In my veterinary practice, I often see them on white breeds, including Maltese and Bichon Frise. Lesions like this can be skin tags and warts. We typically see ‘old age warts’ in senior dogs, as their immune system is weakened, and they are less able to prevent these growths from appearing. Once a dog has one, they generally develop more and more as they get older.

Of course, a pink bump on your dog’s lip could be other things too. The color is not a definitive way of telling us what the lump is. Some cancers, including mast cell tumors and carcinomas, can be pink. Learn more and view pictures with my article on: Pink or Red Spots on a Dog’s Lips.

“Mast cell tumors are made up of cells that contain histamine. These tumors should never be squeezed, as this can result in a life-threatening anaphylactic reaction in the dog.”

Dr. Jamie Whittenburg (DVM)

Veterinarian at Senior Tail Waggers

2. Red spot on dog’s lip

If your dog is young and they develop a smooth red lump just beside their lip, this may well be a histiocytoma. These growths affect dogs that are less than six years of age. Oftentimes, a histiocytoma will disappear within a few months, without us having to intervene.

Even in young dogs, however, we cannot be sure a growth is a histiocytoma just from the appearance. Tumors, including mast cell tumors, can look very similar, so your vet might suggest a fine needle aspirate (FNA) to confirm the suspected diagnosis.

If your dog has had a red bump on their lip for just a few days, we should also consider other eventualities. For example, maybe they managed to bite their lip and there is now a little blood blister. Or perhaps they’ve been stung by an insect. Lesions like this tend to resolve within the week. Read my article on: Pink or Red Spots on a Dog’s Lips.

3. White bump on dog’s lip

Less commonly, we might find that our dogs have a white spot on their lip. Some fleshy white growths will turn out to be papillomas (warts). Young dogs can develop papillomas on the outside and inside of their mouth, if they have been exposed to another dog with warts. These contagious growths cannot be passed on to humans.

warts on a dog's lips
Example white bump on a dog’s lips

The majority of warts in young dogs will resolve within a few months and are not treated. In some unlucky individuals, the warts may proliferate and cause issues with chronic infections and difficulty eating. Your vet may consider surgical removal or a “recombinant vaccine” whereby the DNA of the papilloma vaccine is injected into the dog, causing them to mount a more effective immune response. Learn more: white spots or bumps on dogs’ lips.

4. Green or yellow spot on dog’s lip

If you’ve noticed a green or yellow bump, you may be dealing with a pustule. This is a little skin blister that is caused by a bacterial skin infection.  Any breed can develop these, but those prone to allergies, like the Frenchie and British Bulldog, would be more predisposed. We can see pustules in those with ‘canine acne.’

My dog has a new bump on his lips. What could it be?

Let’s take a look at all of the potential contenders when our dog develops a new lip lump.

Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.

1. Papilloma

A papilloma is caused by the papillomavirus, and it is generally younger dogs that are affected. While we can see warts anywhere, most appear on or in the mouth and lips. Papillomas are usually light-colored: pale pink or white, and look like ‘little brains.’

They are not always well attached to the skin and sometimes bleed when they hit something. Most young dogs are unaware that they have them and are not bothered by them.

papillomas in a dogs mouth
Papillomas on the lips inside the mouth

Vets will be happy to diagnose a papilloma based on the appearance, and we usually take a ‘wait and see’ approach, as the papilloma should go without treatment in just a few months. View more pictures of dog warts/papillomas.

WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]

2. Old age skin tag

When dogs enter their teenage years, it is not unusual for them to start developing skin tags or ‘old age warts.’ These can appear anywhere on the body, including near the lips.

These skin tags can hang on a ‘stalk’ or may be more firmly attached to the body. Most skin tags are a fleshy color, but they can have pigment too.

Your vet may be happy to monitor the growth, or they might suggest surgical removal. A vet is more likely to want to remove the skin tag if it is affecting your dog by e.g. causing them trouble with their eating or developing constant infections.

elongaged skin tag on dog

3. Tumor (such as a mast cell tumor, histiocytoma, or sarcoma)

In some cases, a lip lump will turn out to be a cancerous tumor. As a rule of thumb, cancers will be fast-growing, and the skin surface can ulcerate and bleed. It is not uncommon for tumors, especially large ones, to develop infections on the surface.

mast cell tumor on dog
(Photo: Joel Mills Wikimedia Commons)

Even if a dog has a relatively large tumor, they will not necessarily act any differently. Indeed, even malignant cancers don’t tend to cause pain. A suspected tumor will be sampled, either by taking an FNA or biopsy.

“Unfortunately, there is no reliable way to determine if a lip mass is benign or malignant just by looking at it. A biopsy or fine needle aspirate is a must.”

Dr. Jamie Whittenburg (DVM)

Veterinarian at Senior Tail Waggers

The treatment and prognosis would depend on the type of tumor and the tumor grade. Most malignant growths would be removed as soon as possible, with the vet ensuring they get clean margins. In some cases, dogs would also undergo chemotherapy. Learn more about the types of tumors often found on a dog’s lips.

4. Pustule

A blister filled with pus can appear on or near the lips, and you may find your dog is itchy, rubbing, and scratching at the lesion. These pustules can occur alongside allergic dermatitis and canine acne. Click here to view pictures of dog acne.

dog acne and pimples on a pug

For most dogs, treating the underlying skin disease will ensure that the pustules resolve. This can include antibiotics and medicated washes containing Chlorhexidine. If your dog does have a food or environmental allergy, we’d ideally identify what they are reacting to and try to avoid it where possible.

5. A recent insect bite or injury

Of course, there may be a simple explanation when we find a new lump, like a wasp sting or a scab after an injury. These sorts of lesions should only last a few days and would only be expected to cause mild discomfort. This lip bump below could be the result of a recent insect bite or injury. If it has been present for more than a week and is not resolving, your vet may consider sampling it, to rule out something else, such as a tumor:

Owners can bathe these lesions at home with cotton wool and salt water, to help prevent infection, and they should resolve quickly.

Can I just wait to see how the bumps or spots evolve, before calling my vet?

It is normally advised to wait 1-2 weeks after first noticing a lump on the lip, especially if the dog is young and showing no signs of discomfort. However, if the lump has not resolved in this time, it is best to have it examined by a veterinary professional.

5 Signs that your dog needs veterinarian help now

It is time to book a vet visit if:

  • The lump has been present for two weeks and is not reducing in size
  • The lump is bleeding or infected
  • Your dog is bothered by the lump or seems very itchy or sore
  • Your dog also has a skin disease
  • Your dog is elderly or has a history of cancer

How will the vet reach a diagnosis, and what will it cost?

It is not possible to accurately diagnose lumps and bumps from their appearance. Your vet ill likely advise sampling the lump and sending the cells to a lab for analysis.

The cost of this will vary depending on the clinic and which sort of biopsy procedure is used. Simple FNAs cost about $150-300, while biopsies done under anesthetic may cost $400-600.


  • Dr. Linda Simon, Veterinarian

    Dr Linda Simon (MVB MRCVS) has 10 years of experience as a veterinarian. She is a veterinary surgeon with a special interest in geriatric patient care, dermatology and endocrinology. She is a member of the British Royal College of Veterinary Surgeons. She graduated top of her class from UCD School of Veterinary Medicine in Dublin in 2013. Linda has also worked as a locum vet in a range of clinics, including 24 hour emergency clinics and busy charity clinics.

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