Introduction

• Bacterial infection affecting the dermis and possibly the subcutis, sometimes causing systemic illness; lesions can be local or generalized.
• Cause: predisposed by immunosuppression, eg FeLV or FIV infection demodicosis   Demodectic mange, endocrinopathy, hypersensitvity, trauma, may be idiopathic.
• Now recognized that EGC Eosinophilic granuloma complex disease is often complicated by bacterial infections.
• Signs: papules, pustules, furuncles, granulomas, ulcers, discharging sinuses; bacterial infection of dermal and subcuticular tissues; scarring where lesions have healed.
• Diagnosis: history, clinical signs, cytology, histopathology, bacteriology.
• Treatment: identification of cause, antimicrobial / antibiotic therapy.
• Prognosis: depends on cause.

Pathogenesis

Etiology

Localized furunculosis

• Feline acne - usually idiopathic.

Generalized furunculosis

• Sequel to folliculitis.
• Secondary to bacterial, eg staphylococci, beta-hemolytic streptococci, Pasteurella multocida  Pasteurella multocida.

Anaerobic cellulitis

• Trauma, eg bites, puncture wounds. Cat bite abcess.
• Foreign body.
• Surgery.
• Burns Burns.
• Neoplasia Skin: neoplasia.
• Indwelling catheter.

Subcutaneous abscesses

• Bite wounds.

Eosinophilic granuloma or ulcer

• Hypersensitivity:
  • Ectoparasites especially to fleas Flea bite hypersensitivity.
  • Atopic dermatitis Skin: atopic dermatitis.
  • Food allergy Food hypersensitivity.
  • Contact Skin: allergic contact dermatitis.
• Idiopathic.

Bacterial pseudomycetoma

• Trauma, eg bite wounds.
• Foreign body.
• Usually coagulase-positive staphylococci.
• Multiple organisms may be involved, eg Pseudomonas spp, Proteus spp, Streptococcus spp, and Actinobacillus spp.

Mycobacterial granuloma

• Cutaneous tuberculosis, Mycobacterium tuberculosis  Mycobacterium tuberculosis, M. bovis  Mycobacterium bovis.
• Feline leprosy Leprosy, unknown cause, possibly M. lepraemurium  Mycobacterium lepraemurium.
• Opportunistic mycobacteria Skin: panniculitis due to rapidly growing mycobacteria.

Actinomycosis

• Rare, several species implicated Actinomycosis.

Actinobacillosis

• Rare, Actinobacillus lignieresii.

Nocardiosis

• Rare, Nocardia spp Nocardia spp.

Predisposing factors

General

• Immunosuppression (FeLV Feline leukemia virus disease, FIV Feline immunodeficiency virus disease), progestagen therapy.

Pathophysiology

• Superficial pyoderma  →  deeper into follicles (folliculitis)  →  rupture of follicular wall  →  pyogranulomatous perifolliculitis or furunculosis in dermis and subcutis  →  extension along tissue planes  →  fistulae on surface or cellulitis and panniculitis in subcutaneous and fatty tissues.
• Bacteria commonly involved include: staphylococci  Staphylococcus spp, Proteus spp , Pseudomonas spp Pseudomonas spp, E. coli  Escherichia coli.

Diagnosis

Treatment

Prevention

Outcomes