Introduction

• Cause: follicular infection that breaks through hair follicle → furunculosis.
• Begins as surface or follicular infection (bacterial, fungal or parasitic).
• Signs: vary from discrete papular lesions to poorly demarcated areas of alopecia, tissue swelling and inflammation.
• Certain types clinically distinctive entities, eg canine acne Skin: canine 'acne' , pododermatitis and furunculosis Skin: pododermatitis and furunculosis , idiopathic furunculosis of German Shepherd Dog Skin: 'idiopathic' furunculosis (German Shepherd Dog) , pyotraumatic folliculitis Skin: pyotraumatic folliculitis , callus dermatitis.
• Diagnosis: signs, histopathology.
• Treatment: antibiotics.
• Prognosis: good with treatment.

Pathogenesis

Predisposing factors

General

• Demodicosis Skin: demodectic mange.
• Hyperadrenocorticism Hyperadrenocorticism.
• Long-term glucocorticoids.

• Hypersensitivity.
• Ectoparasites Skin: parasitic disease - overview.
• Endocrine/metabolic disease.
• Immunologic incompetency, eg neoplasia.
• Poor nutrition.
• Unhygienic environment.
• Anatomical factors, eg facial, lip, tail, vulvar and body folds.
• Environmental factors, eg high temperature and humidity.
• External trauma.

• Viral infection.
• Idiopathic keratinization defects.

Specific

• Staphylococcus intermedius Staphylococcus intermedius.

• Staphylococcus aureus Staphylococcus aureus.
• Streptococcus spp Streptococcus spp.
• Pseudomona sspp Pseudomonas.
• Proteus spp Proteus spp.
• Nocardia Nocardia spp.
• Dermatophilus.
• Mycobacterium spp.
• Escherichia coli Escherichia coli.

Pathophysiology

• See also anal furunculosis Perianal fistula.

• Continuation of superficial pyoderma deeper into follicles → 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.
• Consequentially, the dual problems of infection and foreign body granulomas co-exist.

Diagnosis

Treatment

Prevention

Outcomes