Folliculitis in dogs: symptoms and treatment

Overview

Superficial bacterial folliculitis is confined to the superficial part of the follicle. It is the most common form of canine superficial pyoderma. Pyoderma is a broader term for pus-forming skin disease. However, not all skin pustules are bacterial.

In furunculosis, a follicle has ruptured and its contents cause inflammation deeper in the skin. This deep form differs from superficial folliculitis. Deep infection carries a greater risk of bacteria entering the bloodstream.

In impetigo, pustules develop separately from follicles, often on hairless skin. In puppies, this is often called puppy pyoderma.

Causes

Normal skin bacteria multiply

The most common cause is Staphylococcus pseudintermedius. This bacterium also belongs to the normal skin and mucosal flora of many healthy dogs. It causes over 90% of superficial pyoderma cases. Finding it on skin alone therefore does not establish an infection needing treatment.

Infection usually develops when an underlying factor disrupts normal skin protection. Allergies, external parasites and local injuries are common predisposing causes. Abnormal keratinisation can also predispose skin to infection. Hypothyroidism or Cushing's disease can reduce skin defences.

Parasites, fungi and follicular injury

Demodex mites can cause similar follicular signs. Ringworm-related folliculitis is also distinguished from the bacterial form. Keratin released into skin from a ruptured follicle can sustain a foreign-body reaction. In that situation, inflammation is not caused solely by bacteria multiplying on the surface.

Hand-stripping hair too early can cause folliculitis. Deep folliculitis or furunculosis can rarely develop after vigorous grooming and bathing.

The absence of a sebaceous plug at the canine follicle opening may partly explain susceptibility.

Risk factors

Warm, moist skin favours bacterial growth. Folds, armpits and spaces between the toes are therefore vulnerable. Repeated pressure on elbows or hocks can irritate and damage follicles.

Allergic skin disease increases recurrence risk if the underlying condition remains uncontrolled. A disease weakening skin defences can also predispose to deep infection. Inadequate grooming is another predisposing factor for superficial infection.

Developmental follicular abnormalities can also predispose to superficial bacterial infection. Dogs receiving frequent antibiotics have a greater risk of carrying antibiotic-resistant MRSP.

Typical symptoms

Superficial bacterial folliculitis may affect the abdomen, inner thighs and top of the neck. Changes can also spread more widely. In a short-haired dog, hair loss may give the coat a moth-eaten appearance.

• Small red spots appear at hair bases.
• Small pustules form.
• A burst pustule may leave a scaly ring with a red edge.
• Crusts or scales accumulate.
• Hair is lost from numerous small areas.
• Your dog scratches or licks itchy skin.

Deep inflammation may cause pus-draining tracts or painful swollen areas. The skin may have a strong odour. Post-grooming deep infection typically causes lesions within 24–48 hours. Fever and lethargy may accompany it.

Spots, pustules and scaly rings at different stages may coexist. Darker skin can remain at the centre of a healing scaly ring. Hair may detach unusually easily from inflamed areas. In short-haired dogs, follicular spots can resemble urticarial wheals.

Complications and consequences

Scratching and licking can break hairs and cause hair loss. Deep inflammation may extend into the dermis. Longstanding deep inflammation can heal with scars. Scarred skin may remain hairless and more sensitive.

Symptoms readily recur if allergy, parasites or another underlying cause remains untreated. An unsuitable antibiotic or missing follow-up can also lead to recurrence. Treatment therefore aims both to resolve infection and control the predisposing disease.

MRSP means meticillin-resistant Staphylococcus pseudintermedius. Many common antibiotics are ineffective against these infections. In one northern European surveillance dataset of clinical S. pseudintermedius isolates in 2024, 5% were MRSP. This figure concerns tested isolates, rather than the infection risk for dogs in general.

Diagnosis at the vet

Cytology confirms bacterial infection

Your vet reviews the history and examines all the skin. Cytology looks for inflammatory cells and bacteria. Bacteria inside white blood cells support infection. Malassezia yeast may also be found.

A sample can be taken from an opened pustule or beneath a crust by pressing a slide against skin. Tape sampling suits dry, greasy or hard-to-reach sites. Antibacterial treatment is selected only after a bacterial cause is confirmed.

Other follicular conditions and underlying causes

A deep scraping or hair sample helps look for Demodex mites. Ringworm can be investigated using hair microscopy, fungal culture or PCR. A Wood's lamp can help find hairs suggesting ringworm. Immune-mediated pemphigus can resemble folliculitis.

If lesions do not improve as expected, a biopsy may be needed to refine the diagnosis. Unusual nodules may require differentiation from a tumour or foreign-body reaction. Blood, urine and hormone tests are used if internal disease is suspected. Suspected food allergy may require a veterinary-planned elimination diet.

An elimination diet investigating food allergy usually lasts 4–12 weeks. If symptoms improve, a veterinary-guided food challenge confirms the diagnosis.

Culture and susceptibility testing

Culture and susceptibility testing help select a systemic antibiotic, one acting throughout the body. Samples are particularly needed for recurrent or deep infections and suspected resistance. Culture is interpreted alongside cytology from the same area. Even healthy skin can yield a positive culture, so this alone does not confirm folliculitis. Repeated previous antibiotic treatments increase suspicion of resistance.

A deep infection sample is collected to represent the actual infected focus. A surface swab alone can miss the organism responsible for deeper disease. Sampling a deep or painful lesion may require pain relief or general anaesthesia.

Treatment

Topical care for superficial infection

Your vet plans treatment according to depth and the confirmed cause. First-line treatment for superficial bacterial folliculitis is a topical antimicrobial. Topical antiseptics are generally preferred to topical antibiotics. An antiseptic reduces surface bacteria.

Medicated shampoo or spray can treat a large area. A medicated wipe or cream may suit a small, local lesion. Foams and gels are also available. Product selection depends on lesion extent, coat and practical feasibility.

Chlorhexidine, for example, is used as a topical antibacterial antiseptic. A long or dense coat can be shortened over the affected area if needed. A collar can prevent licking. Itchy allergic skin may also need anti-itch medication.

Chlorhexidine disrupts bacterial cell membranes and damages proteins. Shampoo can also remove crusts, scale and unpleasant odour. A product may reduce biofilm, a bacterial layer attached to a surface. Topical care reduces the need for systemic antibiotics. Avoiding systemic antibiotics also reduces treatment effects on gut microbes. A topical product can also irritate skin or cause contact allergy.

Response and follow-up

Superficial folliculitis lesions usually begin improving with topical care within 1–2 weeks. Most dogs' lesions have resolved after 3–4 weeks of treatment. Response is usually checked after 2–3 weeks. Topical care continues until lesions have healed and the underlying cause is being treated.

Topical treatment was effective in 12 of 13 clinical superficial folliculitis trials. One superficial pyoderma study compared 31 topically treated dogs with 20 receiving oral antibiotics. Over the 4-week study, outcomes did not differ materially between groups apart from a baseline difference. Skin signs of MRSP infection can also resolve with topical care.

When is other medication needed?

Systemic antibiotics are considered when topical care fails or cannot be carried out. If skin does not improve after 2 weeks of topical care, implementation and possible underlying disease are reassessed. Deep bacterial infection usually needs a systemic antibiotic. Topical care can support healing alongside it.

With appropriate systemic treatment, superficial lesions should begin improving within 5–7 days. Failure requires another sample or review of the plan. Painful deep inflammation may also need pain relief. Ringworm can require both topical and systemic antifungals.

Prevention

Identifying and treating the predisposing disease is central to preventing recurrence. Parasite protection should suit your dog's needs. When frequent medicated bathing is planned, the effectiveness of spot-on parasite protection is also reviewed.

Hand-strip hair only once it releases easily without hurting your dog. Brush down to the skin and gently detangle. Dry your dog thoroughly after washing. Avoid excessively hot drying air.

Your vet may plan proactive topical antiseptic care to prevent recurrent infections if needed.

Important for dog owners

Watch for new spots, pustules and scaly rings. Record whether itching decreases and pain or discharge changes. Tell your vet about bathing, grooming and previous antibiotics.

Comb out loose hair and undercoat before medicated bathing. Residual redness does not always mean active bacterial infection. Hair loss may persist for up to about 6 weeks after other lesions heal.

Mention known MRSP carriage when booking. MRSP can spread through animal contact, equipment and hands. Accustoming your dog to handling makes care easier during illness.

Frequently asked questions

Does folliculitis always need an antibiotic course?

First-line care for superficial bacterial folliculitis is usually topical antimicrobial treatment. A systemic antibiotic is considered if local care is insufficient or impractical. Deep inflammation is assessed separately, with selection guided by culture and susceptibility testing.

Can folliculitis spread to other dogs or people?

Transmission risk depends on the underlying cause. MRSP can spread between dogs through hands and equipment too. Human MRSP infection is rare. Ringworm, however, can spread to other animals and people.

How quickly does skin heal with topical treatment?

Superficial bacterial lesions should generally start improving within 1–2 weeks. Most resolve after 3–4 treatment weeks. Hair recovery can take longer: patchy hair loss may remain for about 6 weeks after spots and pustules disappear.

Why does infection return after treatment?

A common reason is that the predisposing disease remains unidentified or uncontrolled. It may be allergy, external parasites or hormonal disease, for example. An unsuitable antibiotic or missing follow-up can also contribute, so reassessment is needed instead of simply repeating the same care.

Can folliculitis begin after grooming?

Hand-stripping too early can damage follicles and cause inflammation. Deep furunculosis associated with bathing and vigorous grooming typically appears within 24–48 hours. Concurrent fever, lethargy or marked pain requires urgent examination.