CONDITION

Pemphigus

Pemphigus encompasses a group of autoimmune skin diseases where the immune system attacks the connections between skin cells, causing blistering, crusting, and erosions, with pemphigus foliaceus being the most common form in dogs and cats.

Why this matters now

Pemphigus can develop at any age, though middle-aged animals are most commonly affected. Certain breeds including Akitas, Chow Chows, and Newfoundlands show increased susceptibility. The condition may arise spontaneously or occasionally follow drug administration or other triggers.

The disease typically begins with localised skin changes that progressively spread. Initial lesions may appear minor—small blisters or pustules—but the fragile nature of these lesions means they quickly rupture to form crusts and erosions. Without treatment, the condition tends to spread to involve larger areas of the body, with the face, ears, and footpads commonly affected.

Signals & patterns

Early signals

Pustules on the skin

Small, fluid-filled bumps that may initially be mistaken for infection, often appearing on the face or ears.

Crusting on the nose or ear tips

Yellowish or brown crusts forming on the nose, ear margins, or around the eyes.

Footpad changes

Thickening, cracking, or crusting of the paw pads, sometimes with pain when walking.

Hair loss in affected areas

Patchy areas where fur has fallen out, often with underlying crusting or erosion.

Later signals

Widespread crusting

Extensive crusty lesions spreading across the face, ears, body, and limbs.

Skin erosions and ulcers

Raw, weeping areas where the surface layer of skin has been lost.

Secondary infection

Bacterial colonisation of damaged skin causing additional discharge and odour.

Systemic illness

Lethargy, reduced appetite, and fever may accompany severe or widespread disease.

Click to read about the biological mechanisms

How this is usually investigated

Diagnosis requires demonstrating the characteristic changes within the skin, as the clinical appearance alone can mimic other conditions. Biopsy and microscopic examination are typically necessary.

Clinical examination

Purpose: Identifies the pattern and distribution of skin lesions
Considerations: Characteristic facial and footpad involvement provides diagnostic clues; photographs document progression.

Skin cytology

Purpose: Examines cells from pustules or under crusts for characteristic acantholytic cells
Considerations: Quick bedside test; supports diagnosis; finding rounded, detached skin cells is suggestive but not definitive.

Skin biopsy

Purpose: Provides tissue samples for microscopic examination to confirm diagnosis
Considerations: Essential for definitive diagnosis; best samples from fresh pustules; multiple sites often sampled.

Histopathology

Purpose: Microscopic analysis reveals characteristic cell separation patterns
Considerations: Distinguishes pemphigus from other blistering diseases; identifies which form is present.

Immunofluorescence or immunohistochemistry

Purpose: Demonstrates antibodies deposited in the skin
Considerations: Confirms autoimmune nature; may be performed on biopsy tissue; specialist laboratory required.

Blood tests

Purpose: Assesses overall health and monitors for treatment side effects
Considerations: Baseline values important before immunosuppressive therapy; ongoing monitoring required during treatment.

Options & trade-offs

Management requires suppressing the autoimmune attack on the skin, typically through immunosuppressive medications, often requiring long-term or lifelong therapy.

Glucocorticoids

Corticosteroids such as prednisolone to suppress the immune response

Trade-offs: Often effective at inducing remission; significant side effects with long-term use; dose adjustments needed; most common first-line treatment.

Steroid-sparing immunosuppressants

Drugs like azathioprine, mycophenolate, or ciclosporin to reduce steroid requirements

Trade-offs: Allow lower steroid doses; take weeks to reach full effect; each has specific monitoring requirements; cost considerations.

Combination therapy

Using multiple immunosuppressive agents together for synergistic effect

Trade-offs: May achieve better control than single agents; increased monitoring needed; requires careful dose adjustment.

Topical therapy

Creams or ointments containing immunosuppressants for localised lesions

Trade-offs: Can help localised disease; reduces systemic medication needs; requires cooperation for application; limited penetration.

Trigger avoidance

Identifying and removing potential triggers such as medications or UV exposure

Trade-offs: Important when triggers identified; may allow dose reduction; not always possible to identify causative factors.

Secondary infection treatment

Antibiotics when bacterial colonisation complicates the condition

Trade-offs: Addresses infection component; culture and sensitivity guide selection; essential for infected lesions.

Common misconceptions

Misconception:

"Pemphigus is a type of allergy"

Reality:

Pemphigus is an autoimmune disease where the body attacks its own tissues, fundamentally different from allergic conditions despite some visual similarities.

Misconception:

"Skin diseases with crusting are usually infectious and need antibiotics alone"

Reality:

While secondary infection can occur, pemphigus requires immunosuppressive therapy to address the underlying autoimmune process.

Misconception:

"Animals with pemphigus cannot have good quality of life"

Reality:

With appropriate treatment, many animals achieve good disease control and maintain comfortable, active lives, though ongoing medication is typically required.

Owners noticing persistent crusty skin lesions, particularly on the face, ears, or paw pads, may recognise these as potentially significant skin changes warranting investigation. Understanding that some skin conditions reflect internal immune dysfunction rather than infection helps frame expectations about diagnosis and management.

Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS