Finding a lump or bump on your dog is concerning, to say the least, but not all lumps and bumps are created equal. This is particularly true for dog warts, also known as canine papillomatosis, which is benign growth that is likely to still worry dog owners. Here's what you must know should you ever encounter warts on dogs.

What are Dog Warts?

Dog warts are benign growths (also called tumors or papillomas) on your dog’s skin. The papilloma or wart is most often flash colored and has the appearance of a cauliflower head with small flesh-colored “heads” clustered together.

This is what a wart on a dog looks like:

What dog warts look like

Although dog warts are most often pink (as shown in the above photo), it is also possible for them to be black, grey, or red and they can also have more or less texture to them. Dog warts may also have a flatter appearance or seem scaly and they can even grow inward rather than outward.

Papillomas or warts can appear just about anywhere on your dog’s body, but the specific virus responsible for causing each type of wart tends to be different. The most frequent site of papilloma warts on dogs is around the mouth or on or around the paws.

What Causes Dog Warts?

Dog warts are also called papilloma’s because they are caused by a virus called the Papillomavirus.

The Papillomavirus is an opportunistic virus that inserts their genetic information into your dog’s cells DNA. This alters how your dog’s cells divide, causing them to divide more often and in an abnormal way. This causes the growth of warts on your dog’s skin.

The Papillomavirus can be transmitted through contact with an infected dog, through toys, bowls, bedding, through cuts and abrasions, or via pests like mosquitoes and fleas.

Are Some Dogs More Predisposed to Warts?

The Papillomavirus is a common virus that all dogs are exposed to at various points during their lifetime. Whether or not a dog develops papillomas after exposure to the virus is dependent on their immune system.

A healthy dog’s immune system will fight the Papillomavirus and it is often unable to take hold. If the virus does cause papilloma growth, warts do not spread to other parts of the body and can usually resolve themselves over a month or two. Warts that are removed from a healthy dog also tend not to regrow because after contracting the virus once, their body has developed an immunity to it.

Although a dog with a healthy immune system does not always present with symptoms, it’s important to be aware that they can still carry the infection and expose other dogs to the virus.

In comparison to a healthy dog, a dog with a compromised immune system is unable to fight against the virus and so it takes hold and causes warts. These warts can spread or recur after removal.

Warts are frequently found in older dogs because they tend to have less robust immune systems. Dogs that have an immune imbalance or autoimmune condition are also susceptible to the virus.

In the case of oral papilloma’s, younger dogs are also often subject to infection because of their undeveloped immune systems.

How Are Warts on Dogs Diagnosed?

Dog warts are easily identified by an experienced veterinarian. Most dogs will, at some point in their life, develop at least one or two of these warts and so the average veterinarian sees their fair share of them during their career.

A visual exam is often enough for a veterinarian to know what they are looking at but to be sure, they may also perform a fine needle aspiration. This requires inserting a thin needle directly into the growth and taking a small sample of the cells that make it up. By looking at these sample cells under a microscope the vet can usually determine the presence of Papillomavirus.

Once in a while, a fine needle aspiration will reveal unclear findings and when this happens, a biopsy may be required. Since papillomas on dogs tend to be smaller growths, the biopsy sample is usually collected by fully removing the wart. The tissue is then sent to a veterinary pathologist who can examine the cells of the growth with more certainty.

How to Treat Warts on Dogs

In healthy dogs, vets often take the “watch and wait” approach to treatment for dog warts. They keep an eye on the wart progression and see if it resolves itself (it usually does) or whether it persists or spreads.

In dogs with a compromised immune system, an active treatment method is more likely. For example, these dogs tend to have more warts which grow in clusters or can grow to be quite large. It is also quite common for immune-compromised dogs to develop infected papillomas which may require surgical removal or antibiotic treatment.

The preferred method of papilloma treatment is surgical removal of the complete growth. The need for removal is generally decided on a case-by-case basis considering the dog’s age, the number of papillomas present, any restriction on comfort or movement caused by the presence of [apillomas, infection, ingrown papillomas, and any other health conditions which may influence a dog’s ability to undergo medical procedures.

If warts are not causing any problems for your dog in terms of movement, infection, or pain, it’s still usually the best choice to leave the growths alone and simply watch and wait.

Should I Remove My Dog’s Warts?

Most veterinarians will not remove papillomas unless they cause problems for your dog’s health or comfort. Keep this in mind when you are debating whether or not you should have them removed yourself at home.

If you feel like wart removal is necessary, talk to your veterinarian about your decision to be sure that you are not putting your dog at risk.

Cosmetic reasons are not a good enough reason to have your dog’s warts removed. If your dog has papillomas already, it means that their immune system is not at it’s best and unnecessary surgical procedures (no matter how small) can leave them susceptible to infection.

Are Dog Warts Dangerous?

Canine papillomae are usually not a cause for concern themselves (although very rarely they can become cancerous), but they can be the cause of a more serious condition or a sign of something more serious.

Firstly, papillomas can become infected if they are repeatedly scratched, bitten, knocked, or otherwise irritated. If left untreated, an infection can spread and lead to more serious health problems in your pet.

Secondly, if the dog has developed an ongoing series of papillomas, it is a sign that their immune system is not as robust as it should be. In this instance, you should maintain a close relationship with your vet so that you can watch or test for symptoms related to auto-immune diseases or simply monitor lower immune system function.

Also keep in mind that while papillomae are generally not dangerous, it’s important that you confirm that you are dealing with actual papillomas first. It is possible for other growths or lesions to look similar to dog warts when they are much more sinister in nature.

Can Dog Warts Be Prevented?

If your dog is infected with the Papillomavirus and you know that they are infected, do not allow them to come into contact with other dogs. Since the virus is contagious with direct contact, you can prevent other dogs from becoming infected by keeping your pooch at home until the virus subsides.

Lastly, if your pet has a compromised immune system, avoid taking them to areas where they may be exposed to the Papillomavirus such as dog parks and kennels.

Is There a Connection Between Dog Warts and Vaccines?

Some people believe that there is a connection between the development of papillomae and vaccinating dogs. This is a tricky assumption because pet owners often take it a reason to stop vaccinating their pets altogether. This is NOT the answer.

When I say that vaccinations can lead to the development of Papillomavirus, we are talking about OVER-vaccination. All dogs should receive their core vaccines and each annual booster should be preceded by a titer test that will determine whether or not a booster shot is necessary.

This alternative to needless annual vaccinations means that your dog’s immune system is not taxed unnecessarily with vaccinations that aren’t needed. This also means that if your dog is exposed to the Papillomavirus, they are going to be less likely to contract it due to a subdued immune system due to over-vaccination.

3 Other Lumps and Bumps Commonly Confused with Warts

There are a few different types of growths on dogs that can be misidentified as papillomas by the untrained eye because they are visually similar. Three of these most common dog skin growths include sebaceous cysts, histiocytomas, and mast cell tumors.

1. Sebaceous CystsSebaceous Cyst on a dog

Sebaceous cysts are the growth most frequently confused with papillomae. These growths are smooth in texture and are colored similarly to papillomae. Sebaceous cysts are benign growths that result from excess sebum building up around hair follicles and creating a lump underneath the skin. As this lump grows it can either “erupt” or it can remain as is.

These types of growth on dogsare usually left alone by vets since they don’t often pose problems and when they are drained, they tend to fill back up again because the “sac” which held the cyst contents is still in place. This sac can be removed via surgery but it is unnecessary in most instances.

2. Histiocytomas

Histiocytomas are another growth that can be confused with papillomas although they tend to be much “angrier” in appearance with a deep red coloration. This type of growth is comprised of immune cells and grows very quickly.

Histiocytoma on dogs

Vets tend to “watch and wait” with histiocytomas because they can resolve themselves, but if they do ulcerate, become problematic, or fail to resolve, surgical removal is best.

3. Mast cell tumors

Mast cell tumor on a dogMast cell tumors are also developed out of immune cells, but they are something to worry about and the reason why you should always consult your vet for a “lump diagnosis” rather than just waiting it out.

Mast cell tumors are cancerous tumors that can take on a wide range of physical characteristics which can make them hard to diagnose without veterinary intervention. These types of tumors grow very quickly and can metastasize and are notoriously difficult to treat, but with early intervention and the right treatment protocol, they can be treated successfully.

When to Visit a Vet for Lumps and Bumps on Your Dog

We always believe that it is better to be safe than sorry when it comes to any veterinary concern. It is a far better feeling to waste the cost of a vet visit and know that your dog is just fine than it is to find out that your dog has had a cancerous growth for the past three months and rather than seek veterinary advice, you decided to watch and wait.

READ NEXT: 9 Common Skin Problems in Dogs (How to Prevent and Treat Them)

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Warts on Dogs - Our Complete Guide

Dana is a qualified veterinarian with background in animal care and training sciences and an avid writer on the topics of dog health. Her range of expertise is wide but her primary focus in on animal nutrition and specifically dog foods.