CONDITION

Pyoderma

Why this matters now

Bacterial skin infections can develop at any age, though they often emerge secondary to underlying conditions such as allergies, hormonal imbalances, or skin trauma. Warm, humid weather tends to create conditions that favour bacterial overgrowth, and dogs with skin folds or dense coats may be particularly susceptible during these periods.

Initial superficial infections may present as small pustules or areas of redness that can spread if the underlying trigger persists. Without addressing root causes, infections often recur or deepen into the dermis, potentially forming painful nodules, draining tracts, or widespread crusting that becomes increasingly difficult to resolve.

Signals & patterns

Early signals

Small pustules or pimples on the skin

Early bacterial infection often appears as raised bumps with white or yellow centres, particularly on the belly, inner thighs, or areas with less hair coverage.

Red, inflamed patches

Areas of skin may appear flushed or irritated, sometimes with a circular pattern as infection spreads outward from a central point.

Mild itching or licking

Dogs may pay increased attention to affected areas, though scratching intensity can vary depending on the level of discomfort.

Patchy hair loss

Infected areas may show thinning coat or circular bald spots where hair has fallen out or been damaged by the inflammatory process.

Later signals

Crusting and scab formation

As pustules rupture and dry, yellowish-brown crusts often develop, sometimes described as having a honey-coloured appearance.

Spreading areas of infection

Multiple patches may coalesce or new areas appear as bacteria spread across the skin surface.

Deep nodules or draining wounds

Severe infections can penetrate deeper skin layers, forming painful lumps that may rupture and discharge purulent material.

Unpleasant skin odour

Bacterial overgrowth often produces a distinctive smell that becomes more noticeable as infection worsens.

Click to read about the biological mechanisms

How this is usually investigated

Diagnosis typically involves visual examination of the skin lesions along with tests to identify the bacteria involved and investigate potential underlying causes.

Skin cytology

Purpose: Examining cells and bacteria collected from affected skin under a microscope helps confirm bacterial infection and may identify yeast involvement.
Considerations: A relatively quick test that provides useful information about the type of organisms present and the inflammatory response.

Bacterial culture and sensitivity

Purpose: Growing bacteria in the laboratory identifies the specific species and determines which antibiotics may be effective.
Considerations: Particularly valuable when infections do not respond to initial treatment or when antibiotic-resistant bacteria are suspected.

Skin scraping or hair pluck

Purpose: Checking for parasites such as Demodex mites that can predispose to secondary bacterial infection.
Considerations: Often performed as part of initial assessment, especially when infection occurs in young dogs or unusual patterns.

Allergy testing or dietary trials

Purpose: Since allergies commonly underlie recurrent pyoderma, identifying allergic triggers may be necessary for long-term control.
Considerations: May involve blood tests, intradermal testing, or elimination diet trials depending on the suspected allergy type.

Hormonal evaluation

Purpose: Conditions like hypothyroidism or Cushing's disease can compromise skin health and predispose to infection.
Considerations: Typically considered when other features suggest hormonal involvement or when infections persist despite addressing obvious triggers.

Options & trade-offs

Treatment focuses on eliminating the active infection while identifying and managing any underlying conditions that predispose to bacterial overgrowth.

Topical antimicrobial therapy

Medicated shampoos, sprays, wipes, or mousses containing antibacterial agents can treat localised infections and support systemic treatment.

Trade-offs: Requires regular application and bathing compliance. Effective for mild cases or as adjunct therapy, but may not suffice for deeper infections.

Systemic antibiotics

Oral or injectable antibiotics treat bacteria from within, reaching deeper tissues and providing broader coverage.

Trade-offs: Often necessary for moderate to severe infections. Treatment courses tend to be lengthy, sometimes several weeks, and premature discontinuation can contribute to recurrence or resistance.

Addressing underlying conditions

Managing allergies, hormonal disorders, or parasites that compromise skin health reduces the likelihood of recurring infections.

Trade-offs: Essential for long-term control but may require ongoing management. Some underlying conditions cannot be cured, only controlled.

Immune-modulating approaches

In some cases, strategies to support or regulate immune function may help dogs prone to recurrent infections.

Trade-offs: May include various interventions depending on the specific situation. Often used alongside other treatments rather than as sole therapy.

Common misconceptions

Misconception:

"Skin infections are contagious to other pets or people"

Reality:

While some bacteria can potentially transfer, most pyoderma develops from bacteria already present on the dog's own skin when conditions allow overgrowth. Simple hygiene measures are generally sufficient.

Misconception:

"A short course of antibiotics will permanently resolve the problem"

Reality:

If underlying triggers such as allergies or hormonal conditions remain unaddressed, infections often recur once treatment stops. Identifying and managing root causes tends to be crucial for lasting improvement.

Misconception:

"Pyoderma indicates poor hygiene or neglect"

Reality:

Skin infections can affect well-cared-for dogs and often reflect underlying health issues rather than cleanliness. Some breeds have conformational features that predispose them regardless of care quality.

Dogs with skin lesions suggesting bacterial infection may benefit from examination to confirm the diagnosis and assess whether underlying conditions might be contributing. Recurrent infections particularly warrant investigation into allergies, hormonal status, or immune function to help prevent repeated cycles of infection and treatment.

Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS