6 Types of Moles on Dogs [With Pics] and What to Do

This article was updated on September 5th, 2023

Whether an owner has come to my clinic specifically because they are worried about a new growth or mole on their dog, or whether that growth has been picked up incidentally by myself or another member of staff, the question on everyone’s lips will be ‘what is it?’.

When a new skin lesion resembles a mole, owners will inevitably wonder: do dogs have moles? The answer is yes. However, we refer to them as ‘nevus’ (singular) or ‘nevi’ (plural). Some owners and vets, however, will use the word mole interchangeably with skin tag or wart.

What are moles on a dog?

Technically, a mole is a nevus. This is a benign skin growth that is usually small and quite symmetrical. Uncommonly, a nevus can be cancerous or can transform into a cancer. Cancerous moles on dogs are quite rare, thankfully. There are lots of types of skin moles including vascular, epidermal and sebaceous gland nevi.

As mentioned, another type of lesion such as a cyst or wart may also be referred to as a ‘mole’ by some patients. Let’s take a look at some of the more common types of moles or bumps, including some pictures of moles on dogs:

• Skin Tags

In older dogs especially, skin tags start to appear. We often see them on the face, elbows, armpits and ankles. They can dangle from the skin and may be dark or a fleshy pink color. They are slow growing and should not bother the dog. Generally, we will monitor skin tags but would not remove them, unless they were becoming a nuisance. Learn more about canine skin tags here.

• Cysts

Dogs develop all kinds of cysts, some of which are fluid filled and others which contain a thicker substance, that resembles cottage cheese. Read our article about the different types of cysts in dogs.

Canine cysts can appear anywhere on the body and may grow to a substantial size. However, most cysts remain quite small. If a cyst is drained, it will refill quickly. Though normally not required, if we do want the cyst removed, this would have to be done by surgically removing the cyst wall.

• Warts

We tend to see warts in two canine populations: Puppies and seniors. This is because both of these age groups struggle to fight off infections and warts are spread by a virus. For puppies, this is due to a lack of natural immunity. For seniors, it is because their immune system is not always working as effectively as it should.

Warts tend to be light pink and can resemble small cauliflowers or brains. For younger dogs, warts usually resolve within a few months. For older dogs, they may persists and grow slowly over time.

Are you wondering if your dog has a wart? Take a look at here and check out the pictures:

• Cancer

A black mole on a dog (rather than white, pink or red mole) is more likely to be a cancer called a melanoma. Some of the more common places for malignant melanoma to occur include the mouth, near the claws and sometimes within the eye. See this picture of a melanoma for an example.

As this tumor can spread around the body, prompt tumor removal and therapy such as chemotherapy or immunotherapy is key when it comes to successful treatment.

• True nevi

A small black or brown mole on a dog may be a true nevus. These moles can appear on the face, flank and paws as well as other locations. As these lesions are benign, there is generally no need to intervene or provide treatment. However, a vet may discuss sampling the lesion to rule out anything more sinister, such as a melanoma.

Related post: Pictures of 11 Common Lumps, Bumps and Growths on Dogs.

What to do when you find a mole or bump on your dog

When a new mole of bump is noticed, it is a good idea to snap a photo, so you can assess if it is growing or changing over the coming days and weeks.

If your dog has been licking or chewing at it, it is wise to use a buster collar to prevent this. This helps ensure the lesion does not become infected.

A lesion that is not going away after a few days should be examined by a vet. Most of the time, new moles or warts will be something we monitor. Less often, your vet may discuss sampling or removal of the lump, particularly if they are concerned about a cancer such as a melanoma.

When is it ok to wait-&-see?

If you’ve only just noticed a small lesion and it is not bothering your dog, you may monitor it over a few days. It could be that it is a small scab or insect sting, which will resolve imminently.

When to consult a veterinarian

It is sensible to consult your vet if the new lesion is persisting for over a week or if it seems to be quickly growing and changing.

A consult should also be booked if a lesion your dog has previously had is suddenly getting bigger or becoming infected.

Veterinary treatment, costs and recovery

For many new lumps and bumps, the cost involved is limited to the consult (about $50), as the vet will be happy that the lesion is benign and needs no intervention.

If the mole needs to be investigated, this will be more costly. This can involve a Fine Needle Aspirate ($150-250) or biopsy ($200-400).

Removing a mole is costly, as it usually means the pet going under anesthetic. This can mean a bill of $350-500. This price should include the lab fees for analyzing the growth.

What causes growth of moles or bumps in dogs?

There is likely a large genetic component when it comes to the development of these lesions, but other factors can play a role too.

•  Exposure to sun. Dogs who spend a lot of time in the sun, particularly those who are short furred, seem more prone to moles and skin tags.
• Side effects of drugs. Some medication such as Apoquel and Prednisone may lead new growths developing and existing growths enlarging.
• Weight gain. Dogs who carry more fat than they should, can be more prone to developing certain lesions.
• Friction. When skin rubs against itself, especially in places like the armpits and groin, this can lead to skin tags developing. 

Frequently Asked Questions

• Can moles or bumps on dogs be cancerous?

Yes, it is possible for these skin lesions to be malignant, which is why a vet visit should be booked for any lesion that is not going away quickly. Read our article about cancerous lesions and bumps in dogs.

• How can I differentiate between a benign and malignant mole or bump?

There is no definitive way to do this without sampling the lesion and looking at it under the microscope. However, malignant lesions do share certain characteristics, such as being quick to grow, ulcerating and becoming infected. Learn more: cancerous lesions and bumps.

• Can moles or bumps on one dog spread to other dogs or humans?

No, moles cannot spread and are not contagious. Warts (papillomas), on the other hand, can spread from dog to dog.

•  Are certain dog breeds more prone to developing moles or bumps?

Yes, as there is a genetic component, we will see certain lumps more often in certain breeds. Poodles, Schnauzers and Golden Retrievers may be over-represented.