Skin fold dermatitis in dogs – symptoms and treatment

Overview

Skin fold dermatitis mainly affects the surface and may also be called fold pyoderma. Bacteria and yeasts normally occur on skin, but conditions within a fold can encourage excessive growth.

Common sites include nasal and lip folds, and around the tail and vulva. Annual prevalence in British primary veterinary care during 2016 was 0.37%.

English Bulldogs had a prevalence of 6.05% among that year's patients. In French Bulldogs, it was 2.69%.

In Pugs, it was 2.11%. The 2016 case group included 974 dogs, with lip fold inflammation in 36.76%.

In the same group, 96.41% had dermatitis at only one location. These figures describe British veterinary patients in the study, rather than all dogs elsewhere or every individual's risk.

Causes

Friction and moisture disrupt the skin's balance

Skin surfaces pressing together rub and reduce ventilation, creating a warm, moist space. Substances produced by microbes irritate the skin and may soften its surface, allowing inflammation to deepen.

Tears and saliva may remain in facial folds, while urine particularly worsens moisture-related damage around the vulva. The skin's own sebum and secretions can also collect at the fold's base and maintain microbial growth.

A common bacterial finding is Staphylococcus pseudintermedius. Malassezia yeast may occur alongside bacteria.

Marked tail folds may involve a DVL2-associated screw tail whose conformation makes skin care difficult. A short-skulled dog may not be able to lick the rear clean, so tail fold discharge can also escape the owner's notice.

Conformation or another condition may underlie the fold

Pronounced folds may result from breed selection, as in many short-skulled dogs. In Shar Peis, inherited mucin accumulation in the skin may increase folding.

Obesity can create new folds or deepen existing ones. Allergic skin disease may increase susceptibility to inflammation, although not every dog with folds develops dermatitis.

Risk factors

In the British study, short-skulled conformation was associated with an odds ratio of 4.51 compared with medium-skulled breeds. English Bulldogs had an odds ratio of 49.07 compared with crossbreeds.

For French Bulldogs, the corresponding odds ratio was 25.92. For Pugs, it was 16.27.

Abundant neck skin in Basset Hounds and pendulous lip folds in spaniels are other typical risk features. The median age of diagnosed dogs in the British case group was 5.10 years, which does not mean the average age at symptom onset.

A small or recessed vulva may also predispose a female to local inflammation. Older age groups were diagnosed more often than dogs under one year old.

Existing atopy, periodontal disease or urinary tract infection can maintain fold problems.

Typical symptoms

Early problems may mainly appear as redness and an odour from the fold.

• The inner surface is red and looks moist or macerated.

• The fold has an unusually strong, unpleasant smell.

• Yellowish or white discharge collects between the skin surfaces.

• Your dog licks, rubs, bites or scratches the inflamed area.

• Opening or cleaning the fold hurts.

• Hair may come away, with crusts or ulcers forming on the surface.

• Tail fold pain may cause rubbing of the rear on the floor or furniture.

Opposing skin surfaces can also become inflamed between the mammary chains or around the scrotum, so examining all the skin is useful. With persistence, the fold may darken, thicken and become noticeably rougher.

Changes usually remain inside the fold initially, rather than spreading widely beyond it.

Complications and consequences

Surface inflammation can ulcerate and recur

Severe dermatitis may cause deep, painful ulcers instead of ordinary redness. Discharge trapped within a fold can maintain inflammation even when the outside looks relatively normal.

A rigid, ingrown tail can prevent skin care and sometimes interfere with passing stools. Inflammation can recur if the original fold conformation or another predisposing condition remains.

Some dogs need lifelong fold care to keep the problem controlled. Repeated need for systemic antibiotics may increase problems associated with antimicrobial resistance.

Diagnosis at the vet

Examining every fold down to the skin

The vet assesses whether the location and boundaries of skin changes match the fold's conformation. Lips, tail and vulval areas are checked too, because inflammation is not limited to the face in every dog.

In one tail fold study from northern Europe, the deepest fold measured four centimetres, illustrating how much skin may be hidden. A very narrow fold may be inadequately cleaned if even a finger cannot fit inside.

A sample may be collected by rolling a cotton swab over the fold skin or using tape. Cell examination looks for cocci, rod-shaped bacteria, yeasts or combinations to guide treatment.

If infection appears deep, bacterial culture and susceptibility testing are important before systemic antibiotics. Similar changes may also result from Demodex mites, mucocutaneous pyoderma or lupus.

A skin biopsy is rarely needed for ordinary fold dermatitis but helps if another underlying condition is suspected. If topical care fails, the diagnosis and possible causes are reassessed, and cell sampling may be repeated.

Treatment

Topical care is usually first-line treatment

The vet prescribes treatment and any medication according to lesion depth, microbial findings and other health conditions. Discharge, dirt and microbial biofilm are cleaned from the fold before specific topical treatment.

Topical antiseptics are preferred as first-line care over topical antibiotics. Guidance for local surface infections also emphasises clipping hair and antiseptic topical care without routine antibiotics.

Careful drying reduces moisture, because a wet fold maintains an environment suitable for microbes. Wipes or gels may reach deep inside a fold, while another topical formulation may suit more extensive lesions.

If rod-shaped bacteria predominate in the cell sample, the vet may add a topical agent effective against Gram-negative bacteria. Products used near the eyes must be safe for that area, so facial fold care is chosen separately.

For broken skin, the vet may choose a product suitable for an open wound rather than an ordinary cleanser. Pain relief may be needed to make topical care possible without excessive distress.

Marked redness, swelling and pain may also require topical anti-inflammatory medication. Yeast overgrowth may need topical antifungal treatment, which ordinary antibiotics do not provide.

Systemic antibiotics are generally avoided in surface fold dermatitis because topical treatment can reach the microbes. Deep infection needs a different approach, planned according to culture findings.

Clinical improvement and improvement in cell samples can often be expected within 7–14 days for surface inflammation. A protective collar may prevent licking and scratching so that skin can heal between treatments.

In a small nasal fold study, 19 dogs received medical-grade honey and 16 a comparison product, so the finding comes from a small study. Over the 21-day comparison, honey did not improve skin and cell sample findings more than the comparison product.

Owners of dogs in the honey group nevertheless reported greater itch improvement, so itching alone did not describe all treatment outcomes.

Correcting the predisposing cause and surgery

Weight loss, dental care and treatment of urinary problems may form part of management according to the fold's location and underlying factors. Controlling atopy or another allergic skin disease can reduce repeated inflammation.

If topical care is insufficient or impossible to carry out, excess folds may be corrected surgically. Surgery may address a deep lip fold, excess skin around the vulva or an ingrown tail.

Deep tail fold surgery can be demanding, so assessment of conformation and pain belongs with the vet.

Prevention

Clean and dry folds regularly so that discharge and moisture do not remain trapped. Use a product as instructed by the vet, because an unsuitable topical treatment can irritate the skin.

Achieving a healthy weight can reduce obesity-related folds and conditions favouring inflammation. If fold conformation cannot be removed, lifelong maintenance care may be needed to reduce recurrence.

Before acquiring a dog, investigate the breed's fold-related skin problems so that long-term care needs are considered.

Important for dog owners

During cleaning, check the deepest part too if this can be done without hurting your dog. Record where smell or redness began and what helped previously. Take a photograph before treatment if changes are easily hidden.

Tell the practice about licking, scratching, weight changes, dental disease and urination problems. Ask for a demonstration of suitable cleaning and drying, including safe handling of a fold near the eyes.

Agree follow-up if the skin does not settle or the same area repeatedly becomes inflamed. Keep records of previous cultures and medication. Do not add another dog's leftover medicine to treatment; report changed symptoms to the practice instead.

Frequently asked questions

Is a bad smell from a skin fold normal?

Smell may be an early sign of inflammation alongside redness. Bacteria and yeasts can overgrow in a moist fold. Examine beneath the hair and fold too, even if the outside looks normal.

Does skin fold dermatitis always need antibiotics?

Topical antiseptic care is usually the first choice for surface inflammation. Systemic antibiotics are avoided for ordinary inflammation limited to the surface. Signs of deep infection require a different treatment approach, with any antimicrobials usually chosen through culture.

Why does inflammation return despite cleaning?

Skin surfaces pressing together can maintain moisture and friction after the initial inflammation settles. Allergy or another underlying cause may also maintain recurrence risk. Without correcting the fold's conformation, maintenance care may be needed long term or for life.

Can an inflamed fold be removed surgically?

Surgery is considered when topical treatment is insufficient or impractical. Areas that can be corrected include lip folds, skin around the vulva and an ingrown tail. Tail fold correction in particular may be demanding, so planning is based on the dog's conformation.

Can fold dermatitis occur anywhere besides the face?

It also occurs in lip folds, beneath the tail and around the vulva. Loose neck skin and obesity-related body folds can become inflamed too. Other folds are therefore checked in a dog with repeated symptoms, rather than treating only the most obvious site.