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
  • 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

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 Pustule.
  • Papules Papule.
  • Crusts Crust.
  • Scaling Seborrhea scaling.
  • Pruritus.
  • Multifocal alopecia Skin: alopecia - overview.
  • Epidermal collarettes.
  • Hyperpigmentation Hypopigmentation.

Typical clinical forms
  • Juvenile pyoderma Juvenile cellulitis.
  • Folliculitis Folliculitis.
  • Superficial pustular pyoderma Superficial pustular pyoderma.
  • Vulvar-fold pyoderma Vulvar-fold pyoderma.
  • Skin-fold pyoderma Skin-fold pyoderma.
  • Callus pyoderma Callus pyoderma.
  • Furunculosis Furunculosis.
  • Interdigital furunculosis Interdigital furunculosis.
  • Pyoderma Pyoderma metatarsus.
  • Granulomatous dermatitis, secondary to pyoderma Granulomatous dermatitis secondary to pyoderma.
  • Bacterial paronychia Bacterial paronychia.

Diagnostic Investigation


Bacteriology
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.
Bacteriology
  • 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

Other causes of pruritus

Treatment

Initial Symptomatic Treatment

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).

Other Sources of Information