Warts on Dogs: Symptoms, Causes, Treatment, and Prevention

If a strange, cauliflower-like bump appears on a dog’s muzzle, it is often a common canine wart. These viral tumors are most frequently seen in young dogs (under two years of age) with immature immune systems and are not contagious to humans. 

While these growths are usually benign and resolve without intervention in young, healthy pups within 1-5 months, the lesions are not always harmless. Especially in senior or immunocompromised dogs, these masses can persist, multiply, or, in rare cases, turn into something more serious like squamous cell carcinoma.

This guide provides the clinical data needed to identify the different types of canine papillomavirus (CPV), how to recognize warning signs of potential malignancy, and the current veterinary treatments, including surgery and emerging non-surgical options like molecular iodine.

Keep in mind that warts are just one of several things that can cause a bump near a dog’s mouth. An older dog, a bleeding growth, or anything that doesn’t quite match the cauliflower description is worth a closer look.

What Do Warts Look Like on Dogs? 

Common viral papillomas typically present as small, flesh-colored or pale pink growths with a rough, “cauliflower-like” texture. Veterinarians refer to this as a “fimbriated” appearance, where the surface looks like it is covered in tiny, finger-like stalks. This unique shape occurs because the virus overrides the skin cells, forcing them to fold and divide rapidly.

While the texture is the primary giveaway, identifying a wart also involves looking for specific location and grouping patterns. Here are the most common types of dog warts:

1. Common Oral Warts (CPV-1 & others)

• Appearance: The classic “cauliflower” or “sea anemone” look; “fimbriated” appearance.
• Location: Lips, tongue, throat, and muzzle.
• Who gets them: Primarily puppies and young dogs under age two.
• The Cause: The virus forces skin cells to fold and divide rapidly, creating that bumpy, “fringed” texture.
• Note: While usually benign, persistent oral lesions in older or immunocompromised dogs should be biopsied to rule out Squamous Cell Carcinoma, which can look very similar.

2. Inverted and Digital Warts (CPV-2 & others)

• On the Body (Inverted): These grow inward, creating a firm, round lump with a central pore (looks like a “cup” under the skin).
• On the Feet (Digital): When these occur on the foot pads, they can be painful and cause lameness. While CPV-2 is a common culprit, multiple virus types can cause these skin-based growths.

3. Pigmented Plaques

• Appearance: Dark, flat, scaly patches (often mistaken for “age spots”).
• Location: Belly, chest, and legs.
• High Risk: Most common in Pugs and Schnauzers. These carry a higher risk of developing into Squamous Cell Carcinoma (SCC) than the cauliflower-type warts. CPV-16 is specifically linked to this malignant change.

Can Dogs Get Genital Warts?

Yes. Canine papilloma viruses can affect the genital region, particularly in areas where skin folds create warm, moist conditions. Cutaneous inverted papillomas are the type most commonly found in the groin and genital areas. Any new growth in this region needs veterinary attention, as genital papillomas can look identical to other conditions that require different treatment.

When to Act if a Dog Wart is Growing

Most warts in young dogs stay small and regress on their own. A wart that is actively growing, spreading to new locations, or changing rapidly is a signal not to wait. Rapid growth, bleeding, ulceration, or a color change are warning signs that removal or biopsy may be needed, especially in dogs over 7 years old or those with a compromised immune system.

Feature	Low Risk (Watch & Wait)	High Risk (Contact Your Vet)
Appearance	Classic “cauliflower” or finger-like stalks.	Smooth, shiny, or looks like a solid “button.”
Color	Flesh-colored, pale pink, or white.	Dark pigment (black/purple), deep red, or bruised.
Skin Surface	Dry and intact.	Ulcerated (open sore), bleeding, or oozing.
Dog’s Age	Young (under 2 years old).	Senior (7+) or dog is immunocompromised.
Growth Rate	Slow or stable for weeks.	Doubling in size rapidly or spreading.
Location	Lips or muzzle (not affecting eating).	Eyelids or foot pads (causing limping).

The viral replication cycle directly drives the growth of a wart. Canine papillomaviruses invade the basal layer of the skin, reprogramming cells to accelerate division while suppressing natural cell death. In the early stages of infection, it is completely normal to see rapid growth before the immune system mounts a response. However, unusually large, rapidly growing, or changing lesions should be biopsied.

Pro-Tip: While some canine papillomas begin to regress within weeks, many veterinarians monitor them for several months. If a wart has not started to regress after about 3 months, or persists for several months without change, further evaluation may be recommended to confirm the diagnosis and rule out other growths, including rare malignant tumors such as squamous cell carcinoma.

What Causes Warts on Dogs?

Papillomas are caused by canine papilloma viruses and over 25 papillomavirus types have been identified in dogs. Although similar to human papilloma viruses (HPV), these viruses are species-specific. Dogs cannot get papilloma virus from humans, and humans cannot get it from dogs.

The virus transmits through direct contact with the papillomas of an infected dog, or with contaminated objects in the environment such as toys, bedding, and food bowls. The virus must enter through injured skin. Dogs with healthy, intact skin resist infection. The incubation period runs 4-8 weeks from exposure to visible symptoms.

Once the virus takes hold, it hijacks the dog’s cells, disrupting normal cell division and triggering abnormal, accelerated skin growth. The virus also disables the normal process of programmed cell death, resulting in persistent tumor formation.

A mature immune system can combat the virus before it takes hold. Young dogs with immature immune systems are most susceptible. Older dogs with weakened immune systems, or those receiving steroids or chemotherapy, face elevated risk.

How Are Dog Warts Diagnosed?

Oral papillomas are usually identified by their appearance alone. That distinctive cauliflower shape is hard to miss. For other wart types, or when there is any doubt, further testing is needed.

A Fine Needle Aspiration (FNA) involves inserting a small needle into the growth to collect a sample of cells for examination on a microscope slide. The procedure is minimally invasive, but results are inconclusive most of the time. This is because papillomas often yield only mature skin cells (keratinized cells) without capturing the deeper ‘hallmarks’ of the virus. When an FNA is inconclusive, a biopsy is the next step.

A biopsy, the surgical removal of a full-thickness tissue sample for evaluation by a board-certified veterinary pathologist, remains the gold standard for a definitive diagnosis. For smaller lesions, the entire mass is often excised during this step. The procedure may require sedation, local anesthetics, or general anesthesia depending on location and the dog’s temperament. One or two sutures may be placed to close the surgical site for better healing.

The sample is then submitted to a reference laboratory for a comprehensive pathology report and final diagnosis. Pathologists specifically look for koilocytes, cells with enlarged, irregular nuclei surrounded by a clear zone known as a perinuclear halo.  This serves as a hallmark of papillomavirus infection. 

Your vet will also rule out other growths that can look similar, including sebaceous adenomas, mast cell tumors, and histiocytomas.

When in doubt, biopsy is the definitive next step.

How Are Dog Warts Treated?  

In most young dogs, warts clear up on their own within 1-5 months as the immune system matures. For healthy young dogs with small, stable warts that are not interfering with eating or walking, watchful waiting is completely reasonable.

However, persistent papillomas in older or immunocompromised dogs should be evaluated because other tumors, including squamous cell carcinoma, can resemble papillomas.

In some cases, oral papillomas may be infected with bacteria from the mouth. If that is the case, oral antibiotics will be prescribed to clear the bacterial infection.

Surgical removal is recommended when papillomas persist for more than three months, interfere with normal function (especially eating), or raise concern about malignant conversion. Cryotherapy, which removes warts by freezing the tissue, is available at some specialty clinics.

Additional treatment options include:

• Azithromycin: An antibiotic that has sometimes been used for its potential immunomodulatory and antiviral effects. While a 10-day course has shown success in resolving oral papillomas in some small studies and case reports, results in clinical practice remain inconsistent. Many veterinarians consider it an adjunctive (supportive) option rather than a guaranteed cure, as it is often difficult to determine whether the medication or the dog’s own immune system ultimately cleared the virus.
• Interferon therapy: Injectable interferon, a cell-signaling molecule the body produces to fight viruses, has been used for HPV in humans with mixed results. Reports in dogs are limited and no controlled studies confirm its safety or effectiveness.  
• Imiquimod: A topical cream that enhances the immune response, used in humans for genital warts and skin cancer. It has shown efficacy against canine papillomas. Skin irritation around the treatment area is common and considered a sign the drug is working. 
• Autogenous vaccine: Some of the dog’s own warts are removed and used to create a therapeutic vaccine administered to the dog, intended to stimulate the immune system to clear remaining tumors. These vaccines were used historically, but the evidence behind them is weak and results have been inconsistent. They are rarely recommended today and require direct veterinary supervision.
• Topical adjuvant therapy: Sometimes, even after a wart is surgically removed, microscopic traces of the virus remain in the surrounding skin, leading to regrowth. “Adjuvant” means an “add-on” treatment. Vets may apply specific medical creams to the surgical site to act as a safety net, helping the immune system kill off any remaining viral cells and preventing the wart from coming back. Recent case studies have shown success using certain adjuvant topical agents after surgery to prevent recurrence in severe cases.  
• Topical molecular iodine: This is not the same as the brown antiseptic (Betadine) found in most first-aid kits. Molecular iodine is a specialized, non-staining form of iodine that can soak through the tough, crusty outer layer of a wart. While not a standard frontline treatment, a case report  has documented successful resolution of oral lesions, showing that molecular iodine can clear oral warts by disrupting the virus’s ability to replicate, offering a non-surgical option for stubborn growths, possibly in the future. 

As with all treatments listed above, your veterinarian will determine the most appropriate option, dose, and approach based on your dog’s breed, age, weight, and specific condition.

Home Remedies and Holistic Approaches

Home Remedies: Does Vitamin E or Castor Oil Remove Dog Warts?

Vitamin E oil applied topically is sometimes discussed in pet owner communities as a home remedy for dog warts. Castor oil and similar topical applications are also popular in online circles. No controlled veterinary trials currently support the effectiveness of these remedies as a standalone topical treatment for canine papillomas. For warts that are growing, causing discomfort, or present in a dog with a compromised immune system, home remedies are not a substitute for veterinary evaluation. In most young, healthy dogs with small, stable warts, the immune system alone is usually sufficient.

Holistic and Integrative Perspectives

Beyond conventional pharmaceuticals, many integrative veterinarians utilize botanical and nutritional protocols to support the immune response, particularly in cases of persistent papillomas. These approaches often include:

• Topically applied essential oils or herbal salves, including Thuja occidentalis, which has been documented in veterinary case reports as a treatment for canine oral papillomatosis and cutaneous papilloma when formulated specifically for veterinary use. Separate case studies found that a topical blend of Sarracenia purpurea, lemon balm, St. John’s Wort, and licorice root resolved canine oral papilloma warts in approximately 9 days.

• Immune-modulating supplements: Because canine papillomavirus often develops when the immune system is immature or weakened, some owners explore integrative approaches to support immune function. One supplement sometimes discussed in veterinary integrative medicine is Turkey Tail mushroom (Trametes versicolor). It contains beta-glucans such as PSK (polysaccharide-K) and PSP (polysaccharopeptide), which have been studied in dogs primarily as supportive therapy for certain cancers like hemangiosarcoma. While no clinical studies have specifically tested Turkey Tail for canine papillomavirus, some integrative veterinarians consider it a general immune-support option that may help the body respond to viral infections.

• Nutritional optimization, particularly ensuring adequate levels of zinc, selenium, and vitamin E, to address underlying deficiencies that may be hindering the dog’s natural antiviral response. Zinc deficiency in particular has been shown to impair T-cell, NK cell, and macrophage function, all of which are directly involved in viral clearance. A comparative treatment study in dogs with confirmed oral papillomavirus used a protocol that included vitamin E, zinc, selenium, and copper supplementation alongside topical and immune-supportive therapy.

While large-scale peer-reviewed data in dogs is still emerging, this is a significant area of growth in integrative veterinary medicine. As we expand our coverage, we will provide more on holistic approaches to canine health to help you make a fully informed decision for your dog.

Always consult with your veterinarian before starting a botanical protocol, as some essential oils and high-dose supplements can interfere with concurrent medications or underlying health conditions.

How to Prevent Warts in Dogs

A preventative vaccine against canine oral papillomas has been developed using recombinant DNA technology. This vaccine has shown significant efficacy in preventing infection and, in some persistent cases, helping to clear up existing warts. For dogs that haven’t responded to standard care, a referral to a veterinary dermatologist is an option for chronic cases requiring advanced immunotherapy.

Because the virus is highly contagious through direct and indirect contact, practical prevention measures include:

• Social Distancing: Avoid direct contact with dogs that have visible papillomas. If your dog develops warts, restrict social contact with other dogs until the growths have completely disappeared.
• Shared Items: Prevent your dog from sharing toys, water bowls, or bedding with infected animals, as the virus can live on these surfaces for some time.
• Protect the Skin Barrier: The virus typically enters the body through tiny breaks in the skin. If your dog has open wounds or skin rashes, it is best to avoid high-contact environments like dog parks or daycares until the skin is fully healed.
• Effective Disinfection: To clean shared areas, use potassium peroxymonosulfate or sodium hypochlorite (bleach-based) solutions. Canine papillomavirus is relatively resistant to alcohol-based disinfectants.

Once a dog recovers from viral papillomas, they develop immunity to that specific type. However, because over 25 types of the virus have been identified, a dog may still be susceptible to other variants throughout their life.

Key Takeaways: Warts on Dogs

Viral papillomas are benign tumors caused by viruses similar to the human papilloma virus but canine-specific. They are not transmissible to humans. Most cases in young dogs resolve within 1-5 months without treatment. Oral papillomas have a characteristic appearance. Other types require fine needle aspiration or biopsy for confirmation. Any wart that grows rapidly, changes color, ulcerates, or fails to regress within three months in an older dog requires a biopsy to rule out malignant transformation. In geriatric or immunocompromised dogs, some papilloma types can convert to malignant squamous cell carcinoma. Several non-surgical treatments exist for persistent or severe cases, each with varying outcomes. Any new lump, bump, or skin discoloration is worth a vet visit, as benign and malignant skin tumors can be impossible to tell apart without diagnostic testing.

 

Note from the Editors: This guide was originally authored by Dr. Winnie, DVM. It was updated to reflect current veterinary safety standards. To ensure the highest clinical standards, this post is currently in our queue for a veterinary re-review.

 

References

• Petmd.com: All about Dog Warts: Types, Causes, and Treatments
• Virology Journal (PMC): Canine Papillomavirus: Status of Diagnostic Methods and Vaccine Innovations (Feng et al. 2025)
• Cureus (PMC): Treatment of a Canine Oral Papilloma With Topical Molecular Iodine (Moskowitz 2025)
• Viruses (PMC): The Detection and Association of Canine Papillomavirus with Benign and Malignant Skin Lesions in Dogs (Chang et al. 2020)
• Brazilian Journal of Microbiology (PMC): Canine papillomavirus type 16 and squamous cell carcinoma in dogs (Alves et al. 2020)
• Papillomavirus Research (PMC): Malignant Transformation of Canine Oral Papillomavirus (CPV-1) Associated Papillomas in Dogs (Thaiwong et al. 2018) 
• MDPI: Papillomaviruses and Papillomaviral Disease in Dogs and Cats: A Review
• MDPI Viruses (2024): Canine Papillomaviruses: An Update — 26 CPV types sequenced
• MSD Veterinary Manual: Oral Papillomas in Dogs
• Acta Scientiae Veterinariae: Canine Oral Papillomatosis, Treatment with Azithromycin and Meloxicam (de Melo et al. 2025)
• Vet World (PMC): Therapeutic Evaluation of Homeopathic Treatment for Canine Oral Papillomatosis (Raj et al. 2020)
• Journal of Biological Innovation (JBINO): Management of Canine Oral Papillomatosis with Thuja occidentalis 30C
• Veterinary Dermatology (PubMed): Azithromycin Therapy of Papillomatosis in Dogs: A Prospective, Randomized, Double-Blinded, Placebo-Controlled Clinical Trial (Yağcı et al. 2008)
• University of Pennsylvania School of Veterinary Medicine: Compound Derived From a Mushroom Lengthens Survival Time in Dogs With Cancer (Penn Vet, 2012)
• Frontiers in Immunology (PMC): Immunomodulatory Properties of Coriolus versicolor, The Role of Polysaccharopeptide (2017) 
• Advances in Integrative Medicine: Topical botanical therapy for the treatment of canine papilloma (Williams et al.)
• Agricultural Science Digest: Virological and Pathological Diagnosis of Canine Oral Papillomavirus in Dogs and Evaluation of Treatment Applications (Karakurt et al. 2023)
• DogCancer.com: Turkey Tail Mushroom For Dogs