Contributors: Karen Campbell, David Scarff
Species: Canine | Classification: Diseases
Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading
Introduction
- Common secondary dermatosis.
- Cause: unclear.
- Signs: pustules with or without range of primary and secondary lesions, +/- pruritus.
- Diagnosis: history, clinical signs. histopathology, bacteriology, microscopy.
- Treatment: antimicrobial therapy.
- Prognosis: depends on type of bacterial infection.
Presenting Signs
- Primary and secondary lesions ranging from papules, pustules and vesicles to crust formation, scaling, epidermal collarettes, hyperpigmentation and ulceration.
- Pustules are the hallmark of pyoderma, but easily rupture so rarely seen.
Pathogenesis
Predisposing Factors
General
- Hypersensitivity Skin: atopy.
- Ectoparasites Skin: parasitic disease - overview.
- Endocrine/metabolic disease Skin: hyposomatotropism.
- Long-term glucocorticoids.
- Immune incompetency, eg neoplasia.
- Poor nutrition.
- Unhygenic 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.
- Staphylococcus epidermidis Staphylococcus epidermidis.
- Streptococcus spp. Streptococcus spp.
- Pseudomonas spp. Pseudomonas.
- Proteus spp. Proteus spp.
- Nocardia Nocardia spp.
- Dermatophilus.
- Mycobacterium spp. Mycobacterium tuberculosis Skin: canine leproid granuloma syndrome.
- Escherichia coli Escherichia coli.
Pathophysiology
- Unclear.
- Host factor +/- predisposing factor (?affecting anatomical and physiological epidermal barrier function) → penetration ofStaphylococcus intermedius Staphylococcus intermedius and its toxins into the skin → bacterial multiplication → exceed a threshold → pyoderma.
Diagnosis
Presenting Problems
- Pustules.
- Pruritus.
Client History
- Skin lesions which may be localized or generalized.
- Pruritus.
- Lethargy.
- Pyrexia.
- Depression.
Clinical Signs
Typical lesions
- Pustules
.
- Papules
.
- Crusts
.
- Scaling
.
- Pruritus.
- Multifocal alopecia Skin: alopecia - overview.
- Epidermal collarettes.
- Hyperpigmentation
.
Typical clinical forms
- Juvenile pyoderma Juvenile cellulitis.
- Folliculitis
.
- Superficial pustular pyoderma
.
- Vulvar-fold pyoderma
.
- Skin-fold pyoderma
.
- Callus pyoderma
.
- Furunculosis
.
- Interdigital furunculosis
.
- Pyoderma
.
- Granulomatous dermatitis, secondary to pyoderma
.
- Bacterial paronychia
.
Diagnostic Investigation
Bacteriology
- Coagulase-positivestaphylococciespeciallyStaphylococcus intermedius Staphylococcus intermedius.
Microscopy
- Diff-Quik or Gram-stained smears of purulent exudate.
- Cellular exudate comprising primarily healthy and degenerative neutrophils with intracellular and extracellular cocci.
- May be difficult to find cocci in older lesions.
- Culture of pustule contents if:
- No response to antibiosis +/- recurrence of lesion.
- +/- Atypical clinical lesions.
- +/- Large numbers of rods found on microscopy.
- +/- Deep pyoderma.
- Coagulase-positivestaphylococciespeciallyStaphylococcus intermedius- commonly isolated.
Histopathology
- Examination of skin biopsy essential for deep pyoderma.
Differential Diagnosis
- Impetigo Skin: impetigo.
- Folliculitis Skin: bacterial folliculitis.
- Hypersensitivity.
- Ectoparasitic infection Skin: parasitic disease - overview.
- Malasseziadermatitis Skin: malassezia disease :
- Dermatophytosis Skin: dermatophytosis.
- Endocrine skin disease Skin: hyposomatotropism.
- Metabolic skin disease.
- Neoplasia.
- Immune-mediated skin disease.
- Drug eruption.
- Demodicosis Skin: demodectic mange.
- Physical causes.
- Contact irritant dermatitis Skin: allergic contact dermatitis.
- Sub-corneal pustular dermatosis.
- Sterile eosinophilic pustular dermatitis Skin: eosinophilic folliculitis and furunculosis.
- Linear IgA dermatosis Skin: linear IgA syndrome.
- Bullous impetigo Skin: impetigo.
- Candidiasis Skin: candidiasis.
- Toxic epidermal necrolysis Skin: toxic epidermal necrolysis.
- Erythema multiforme Skin: erythema multiforme.
- Pemphigus complex.
Treatment
Initial Symptomatic Treatment
- Topical and systemic antimicrobial therapy Therapeutics: antimicrobial drug.
- Treat until 7-10 days after clinical resolution.
Subsequent Management
Monitoring
- Subsequent history and clinical findings.
Outcomes
Prognosis
- Depends on specific disease.
Expected Response to Treatment
Reasons for Treatment Failure
- Predisposing factors not identified and resolved.
- Concurrent corticosteroid therapy - poorly responsive to steroid therapy, bacterial infection should be suspected if skin disease.
- Inappropriate use of shampoo, eg insufficient contact time.
- Inappropriate use of antibiotics, eg penicillin, ampicillin, underdosing, too short duration.
- Inappropriate use of antibiotics that are inactivated by penicillinase, eg ampicillin, amoxicillin, penicillin.
- Inadequate duration of treatment.
- Underdosing of antibiotics.
Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Littlewood J D, Lakhani K H, Paterson S, Wood J L N & Chanter N (1999) Clindamycin hydrochloride and clavulanate-amoxycillin in the treatment of canine superficial pyoderma. Vet Rec 144 (24), 662-665 PubMed.
- Mason I S (1993) Selection and use of antibacterial agents in canine pyoderma. In Practice 15 (3), 129-34 VetMedResource.
- Mason I S (1991) Canine pyoderma. JSAP 32 (8), 381-6 VetMedResource.
- DeBoer D J (1990) Strategies for management of recurrent pyoderma in dogs. Vet Clin N A 20 (6), 1509-24 PubMed.
- Ihrke P J (1987) An overview of bacterial skin disease in the dog. British Vet J 143 (2), 112-8 PubMed.
Other sources of information
- Morrelo K A & Mason I S (1995)Handbook of Small Animal Dermatology.Pergamon Press. pp 127-136, 287-294 (Excellent problem-oriented approaches and diagnostic plans).
- Muller G Het al(1995)Muller and Kirk's Small Animal Dermatology.5th edition. Philadelphia: W B Saunders. pp 280-328 (Detailed dermatology text book for in-depth reading).
- Griffin C E, Kwochka K W & MacDonald J M (1993)Current Veterinary Dermatology - The Science and Art of Therapy.St Louis: Mosby Year Book. pp 3-21 (Well presented dermatology text book).
- Grant D I (1991)Skin diseases in the Dog and Cat.2nd edn. Oxford: Blackwell Scientific Publications. pp 8-27 (Concise for quick reference).
- Locke P H, Harvey R G & Mason I S (1993) (eds) Mason I S & Kwochka K W. In:Manual of Small Animal Dermatology.BSAVA. pp 60-64, 213-232 (Excellent differential diagnosis including frequency of occurrence indicators).