What does a wart look like on a dog?

Finding a small bump on your dog can be unsettling. You want to know whether it’s harmless, contagious, or something that needs treatment. This article focuses on warts—what they typically look like, why they matter, how they behave, and practical steps you can take if you find one. The goal is to give clear, veterinarian-informed guidance so you can act calmly and confidently.

How recognizing warts helps protect your dog’s health

Recognizing a wart matters because early identification affects comfort, infection control, and treatment choices. Groomers often notice bumps around the mouth or paws during a trim; owners commonly discover them while scratching or playing; and vets may find them during routine checks. Warts are caused by viruses and are therefore potentially contagious to other dogs, so understanding what you’re looking at helps prevent spread at dog parks, boarding facilities, or within multi-dog households.

Beyond contagion, warts can cause local problems: they may rub on collars, get irritated by chewing, or interfere with eating or vision when on the lips or eyelids. New owners, breeders, and groomers all benefit from being able to recognize a wart at a glance and knowing the next practical steps to take.

At a glance — what a typical dog wart looks like

At a glance, a typical canine wart looks like a firm, rough, sometimes cauliflower-like bump sitting on the skin. They often feel textured rather than smooth and may be slightly raised above the skin surface. Many are small—about the size of a pea—but some grow larger or form clusters that look like a cobblestone patch.

• Common locations: face and lips, eyelids, inside the mouth, paw pads and between toes, and the trunk or neck. I commonly see them on the lips and around the mouth in young dogs.
• Color and size: most are skin-colored or slightly lighter, but they can be pink, gray, or brown depending on your dog’s skin tone and any secondary changes. Sizes range from pinhead to over a centimeter across; clusters can appear bigger.
• Texture and behavior: they are usually firm and dry, not fluid-filled like a cyst. Some are pedunculated (on a small stalk) and move a little; others are broad-based and flat.

Note that other lumps—skin tags, cysts, insect bites, or true tumors—can look similar. When in doubt, a vet check is the safest course.

Wart biology explained: what causes them and how they grow

Warts in dogs are most likely linked to infection of the skin cells by canine papillomaviruses. These viruses attach to and enter keratinocytes (the cells that make up the outer skin layer) and appear to stimulate those cells to multiply, causing the raised, rough lesion you see. The process is similar in principle to human warts but involves different virus strains that typically affect dogs only.

The dog’s immune system plays a major role. Young dogs with immature immune responses often develop warts more readily, and many lesions regress on their own as immunity matures. Conversely, dogs with weakened immune defenses—because of illness, medications that suppress immunity, or significant stress—may develop more numerous or persistent warts.

It’s useful to distinguish viral papillomas from other skin tumors: papillomas are primarily epidermal (surface) proliferations related to viral effects, while other tumors may arise deeper or have different behavior. If a growth looks unusual, grows quickly, or does not behave like a typical wart, tissue sampling may be needed to clarify what it is.

When and where warts most often appear on dogs

Age is an important factor: puppies and young adult dogs are most likely to develop warts because their immune systems are still learning to recognize and clear the virus. I typically see outbreaks in litters or in dogs that spend time with many other young dogs, such as at kennels or puppy classes.

Transmission commonly occurs through direct contact—nose-to-nose, licking, or sharing toys and bedding with an infected dog. The virus can also survive briefly on fomites, so grooming tools or communal toys may contribute. Broken skin makes infection easier; a small scrape or abrasion may be the entry point that allows the virus to establish itself.

Certain conditions predispose dogs to more frequent or severe wart formation: immune suppression from medications (like high-dose corticosteroids), systemic illness, poor nutrition, high stress levels, or concurrent skin infections. In those cases, warts may persist or multiply rather than resolving.

Warning signs: which warts need prompt veterinary attention

Many warts are harmless and will shrink over a few weeks to months, but some signs suggest you should consult a veterinarian promptly. Rapid growth, ulceration, bleeding, or a change in coloration may indicate secondary infection or a different type of tumor. Lesions that are painful, intensely itchy, or interfering with eating, breathing, or vision require immediate attention.

Multiple spreading lesions that keep appearing, or a wart that fails to regress after several months despite otherwise healthy conditions, may mean your dog’s immune system is not controlling the virus and should be evaluated. Systemic signs—lethargy, weight loss, fever—are not typical of simple warts and might suggest a concurrent illness that needs diagnostic workup.

First steps for owners who find a wart

1. Observe and document. Take clear photos from multiple angles and keep a dated record so you can track size and number over time. Photographs are very helpful for your vet to judge progression.
2. Limit contact and handling. Minimize direct touching of the lesion and prevent other dogs from licking or sniffing it until you know more. Wash hands after contact to reduce spread between pets and people.
3. Schedule a veterinary exam. Share your photos and history: when you first noticed the bump, whether it’s changed, and any other pets that might be affected. The vet will perform a physical exam and may recommend needle cytology, a small biopsy, or watchful waiting depending on appearance and risk.
4. Follow recommended diagnostics and treatment. For typical small papillomas, vets often recommend monitoring because many regress on their own. If lesions are problematic, a biopsy or surgical removal may be advised. Your vet may discuss topical or systemic therapy in specific cases, but these are chosen case by case.

Safe home care and practical management tips

At home, practical measures support healing and limit spread. Keep the area clean and dry; a gentle, vet-approved wound wipe can be used if the surface is crusted or mildly inflamed. Avoid over-the-counter human wart treatments—salicylic acid and freezing kits are not formulated for pets and can cause pain or chemical burns.

Hygiene helps reduce fomite transmission: launder bedding, blankets, and plush toys in hot water; disinfect grooming brushes and collars; and rotate toys less frequently until the lesions have resolved or been cleared by your vet. Keep your dog from communal spaces such as dog parks or daycare until a vet confirms the risk is low.

Supportive care matters. Good nutrition, parasite control, and stress reduction can help the immune system work more effectively. Prevent self-trauma by using a soft Elizabethan collar or recovery suit if your dog is obsessively licking or chewing the site; repeated trauma can delay healing and cause secondary infection.

Useful tools and supplies for inspection and treatment

For monitoring and safe management, useful items include a camera or smartphone for serial photos, a soft Elizabethan collar or recovery suit to prevent self-trauma, pet-safe antiseptic wipes or sprays recommended by your veterinarian, and a secure leash and carrier for vet visits. Keep grooming tools clean, and have a dedicated towel or mat for your dog while the lesion is active to avoid spreading virus to other animals.

Still unsure after treatment? How to proceed

If you’ve followed your vet’s advice and the wart doesn’t shrink or new lesions appear, recheck with your veterinarian. Further diagnostics—a biopsy to look at cellular architecture or specialized testing—may be necessary to rule out other growths or immune-related problems. If you notice secondary infection (increasing redness, pus, or a foul smell), your vet may prescribe topical or systemic antibiotics. For dogs with frequent or severe papillomas, referral to a veterinary dermatologist may be useful to explore immune-supporting strategies or advanced treatments.

Sources and trusted resources

• Merck Veterinary Manual: “Papillomatosis in Dogs” — Merck Veterinary Manual entry on viral papillomas and management
• American Veterinary Medical Association (AVMA): “Canine papillomavirus infection” — client information and guidance on contagion and prevention
• Cornell University College of Veterinary Medicine—Hospital for Animals: “Canine Papillomas” client handout and clinical notes
• UC Davis Veterinary Medical Teaching Hospital—Clinical Dermatology: “Viral Papillomas in Dogs” overview and treatment approaches
• Miller and Griffin, Small Animal Dermatology (textbook): chapters on viral skin diseases and papillomaviruses