What causes skin tags on dogs?

As a veterinarian who spends a lot of time examining dogs’ skin during wellness checks and problem visits, I know that small, soft tags of skin are a common finding that can worry owners more than they need to. Understanding what they are, why they appear, and when to act can make routine grooming less stressful and help you spot issues that really do need attention.

What skin tags mean for your dog’s comfort and long-term health

Skin tags affect a dog’s comfort and the ease of grooming. A small flap of skin in a high-motion area can catch on brush teeth, rub under a collar, or become inflamed if your dog scratches it repeatedly. During a grooming session or when you examine your dog after a walk, those little bumps are easy to miss until they’re irritated. I typically see owners discover them at the groomer, during home brushing, or at a vaccine visit.

Certain dogs are more likely to develop tags. Middle-aged and older dogs tend to have more of them as skin elasticity and circulation change with age. Dogs with heavy skin folds or short necks, and breeds prone to excess skin or obesity, often have more areas where friction and moisture encourage small growths. Some breeds may be genetically predisposed to softer connective tissue that forms tags more easily, and you may notice multiple family members with similar skin changes.

Emotionally, these lumps can be upsetting to owners who fear cancer. They also affect quality of life when they become irritated, painful, or infected. A dog that is frequently stopped by a sore spot under a harness can become sensitive about walks or grooming. Knowing what is typical versus what is dangerous helps you reduce unnecessary worry and take targeted action when it matters.

How skin tags form: the most common causes in dogs

In plain terms, skin tags most often develop where skin rubs against skin or against equipment, where minor repeated trauma or irritation is present, and where older skin responds by forming extra connective tissue. Friction and repeated rubbing are the most straightforward causes. As dogs age, the way their skin heals and the amount of soft connective tissue can change, which makes extra flaps more likely. There is also a genetic component for some dogs, so a predisposition in a breed or family line is possible. Finally, some lesions that look like skin tags—warts caused by viral growths, benign cysts, or certain tumors—can mimic a tag, so it’s important to watch for changes.

Inside a skin tag — the biology, cells and purpose

A skin tag is usually a small outgrowth made up of a core of fibrous tissue and small blood vessels covered by normal skin. The term “skin tag” is a descriptive one; these structures are generally benign and do not serve a function for your dog. They are a local overgrowth rather than a spreading disease. When skin is subjected to chronic low-level irritation, the body’s repair response may produce extra connective tissue in that spot, which can become noticeable as a soft lump.

Some growths that look like tags may not be the simple, benign type. Cells can proliferate for other reasons, and a veterinary exam—often including surface cytology or a small biopsy—may be needed to tell a true skin tag apart from a wart, cyst, or tumor. Hormonal changes or age-related shifts in skin structure are likely linked to an increased number of benign growths, and I often see multiple tags appear in middle-aged dogs without any systemic disease present.

Environment, age and timing: factors that trigger tag growth

Where and when a tag appears gives strong clues to cause. Collars and harnesses create a repeated rubbing point on the neck, and tight or poorly fitting equipment may cause a tag to form at the same spot over time. Dogs with thicker skin folds—along the face, neck, armpit, or groin—experience frequent skin-on-skin contact and moisture buildup that increase friction and the chance of small overgrowths. Overweight dogs are more likely to have these contact points and therefore more likely to develop tags.

High-motion areas such as the axillae (armpits), inner thighs, and the base of the neck are typical sites. I see tags form where leash hardware hits, where a harness seam rubs, or in a fold under a heavy ear. Timing-wise, tags are most often noticed in middle-aged to older dogs; they may appear slowly over months rather than overnight. If new lesions appear rapidly or several come up in a short period, that pattern may suggest something beyond typical friction-related tags.

Red flags to watch for — when a tag requires immediate care

Not every lump is harmless. Seek veterinary attention if you notice rapid growth, a change in color or shape, ulceration or bleeding, persistent swelling, or signs of infection such as pus or a bad smell. If your dog shows pain when the area is touched, is obsessively licking or scratching the spot, or shows changes in behavior—reduced appetite, lethargy, or fever—book an exam promptly. Multiple new lesions appearing quickly or accompanying systemic signs should prompt a veterinary evaluation sooner rather than later, because those patterns may suggest an infectious process or a growth that needs biopsy.

Practical steps owners can take the moment you spot a tag

Begin with careful documentation. Take clear photographs from multiple angles and measure the lesion with a small ruler or include a familiar object for scale; repeat photos every week to monitor change. Note when you first saw the lesion, whether it seems to wax and wane with irritation, and whether it bleeds or discharges. Avoid cutting, tying off, or attempting removal at home—these actions commonly cause infection or incomplete removal that complicates later veterinary management.

If a tag is stable, small, and not irritating your dog, you can watch it while keeping it clean and protected. If the lesion grows, changes, bleeds, or becomes painful, schedule a veterinary appointment. At the clinic, a veterinarian will often examine the lesion, perform a surface cytology or fine-needle sample, and discuss whether removal or biopsy is appropriate. Surgical removal under local or general anesthesia allows the veterinarian to send tissue for histopathology when there is any doubt about the diagnosis.

Reduce friction and irritation: simple changes to prevent new tags

Prevention focuses on reducing repeated rubbing and keeping high-risk areas dry and clean. Use well-fitted collars and padded harnesses that distribute pressure and avoid rubbing a single point repeatedly. For dogs with skin folds, gentle daily cleaning and drying of the folds helps reduce moisture and friction; I typically recommend mild, veterinarian-approved cleansers rather than household soaps that can irritate the skin. Weight management is often the most effective long-term strategy for dogs prone to skin-on-skin contact—losing a few pounds can dramatically reduce fold-related irritation.

Rotate equipment and the placement of tags that sit against the skin: change the position of the collar or harness slightly or swap to a mesh, padded option for walks. During grooming, be gentle around suspicious areas, using blunt-ended clippers or scissor guards to avoid accidental cuts that can create more problems. For dogs that are particularly active or rub a tag frequently, a short-term protective dressing or soft sleeve may be useful while you arrange veterinary care; consult your vet before applying anything that could trap moisture.

Vet-recommended tools and products for safe inspection and care

Having the right, veterinarian-approved items on hand helps you document and protect tags without risking harm. A smartphone or small digital camera is useful for consistent photos. Choose wide, padded collars or fitted, non-chafing harnesses designed to avoid pressure points. For cleaning, products with chlorhexidine in low concentrations are often recommended for fold care—use them sparingly and only as directed by a veterinarian. Gentle grooming tools, such as soft brushes and blunt-tipped trimming scissors, reduce accidental injury during routine care. If your dog’s tag is in a place that repeatedly catches, discuss protective wraps or a temporary soft protective sleeve with your vet rather than improvising at home.

What to expect at the vet: diagnosis, treatment options and recovery

At the clinic, the veterinarian will assess the lesion’s appearance, feel, and history. They may perform a surface smear or fine-needle sampling to look at cells and decide whether a biopsy is needed. If removal is recommended, methods include simple excision, cryotherapy, or other techniques depending on size and location; removal is both diagnostic and therapeutic when the lesion interferes with comfort. Recovery is typically straightforward, and removing an irritated tag often resolves the behavior that was causing the problem—less scratching, easier grooming, and a happier dog.

If the laboratory report identifies a benign, uncomplicated tag, no further treatment is usually required. If the sample suggests a different diagnosis, your veterinarian will discuss appropriate treatment options. Keep in mind that the vast majority of small, friction-related tags are benign, but seeking care for changes or for lesions that bother your dog is the safest course.

References and further reading

• Merck Veterinary Manual: “Skin Tumors in Dogs” — Merck & Co., Inc., Merck Veterinary Manual online section on canine skin tumors and lumps.
• American Veterinary Medical Association (AVMA): “Lumps and Bumps: Managing Skin Masses in Pets” — client information on identifying and approaching skin growths.
• American College of Veterinary Dermatology (ACVD) Client Information: “Skin Lumps and Growths in Dogs” — ACVD handout on common dermatologic masses and when to see a specialist.
• Muller and Kirk’s Small Animal Dermatology, 7th Edition (Elsevier): chapters on cutaneous masses and age-related skin changes in dogs.
• Journal article examples: “Canine cutaneous masses: a review” in Journal of Small Animal Practice and relevant case reports in Veterinary Dermatology for patterns of benign versus malignant growths.