Contributors: Rosanna Marsella, Ian Mason, David Scarff

 Species: Feline   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading


  • An uncommon feline dermatosis (except subcutaneous abscessation Abscess which is common!).
  • Cause: surface, superficial and deep bacterial infections.
  • Signs: pustules, nodules and draining tracts +/- a range of other primary and secondary lesions.
  • Diagnosis: microscopic examination of stained smears, bacterial culture and histopathology.
  • Treatment: antibiotics; surgical resection of nodules.
  • Prognosis: good for surface and superficial infections, poor for some deep infections.

Presenting Signs

  • Surface pyoderma: alopecia, papules and crusts   Bacterial folliculitis .
  • Superficial pyoderma: alopecia, erosions, ulcers, crusts, occasionally draining tracts and cellulitis Furunculosis .
  • Deep pyoderma: nodules, ulcers, draining tracts, systemic signs.



Predisposing Factors


  • Superficial pyoderma: unclear.
  • Surface and deep pyoderma: trauma.


  • Unclear.


Presenting Problems

  • Discharging sinuses.
  • Pustules.
  • Pruritus.
  • Alopecia.

Client History

  • Skin lesions.
  • Abscess formation Abscess  Cat bite abscess .
  • Hair loss.
  • Lethargy.
  • Pyrexia.

Clinical Signs

Typical lesions

  • Nodules.
  • Discharging sinuses.
  • Ulceration.
  • Pustules.
  • Papules.
  • Crusts.

Typical clinical forms

Diagnostic Investigation


  • Pathogenic bacteria.
  • Microscopy - Diff-Quik or Gram-stained smears of exudate, fine needle aspirate or impression smear Skin: impression smear. Modified Ziehl-Nielsen Stain for acid test bacilli.
  • Superficial pyoderma: cellular exudate comprising primarily healthy and degenerative neutrophils with intracellular and extracellular bacteria.


  • See Bacteriology overview Bacteriology.
  • If deep pyoderma suspected.
  • Culture from biopsy sample or discharge from draining tracts if tissue granules present.
  • Special stains Histopathology: special stains required for certain bacteria.


  • If deep pyoderma or mycobacterial disease or pseudomycetoma suspected.

Differential Diagnosis

Causes of nodules, ulceration and discharging sinus

Causes of pruritus, pustules, papules and crusts


  • Other causes of alopecia.


Initial Symptomatic Treatment

Subsequent Management


  • Subsequent history and clinical findings.



  • Surface and superficial pyoderma: good.
  • Deep pyoderma: good to poor.

Expected Response to Treatment

Reasons for Treatment Failure

  • Concurrent corticosteroid therapy.
  • Inappropriate use of antibiotics, eg underdosing - dose +/- duration.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Kennis R A, Wolf A M (1999) Chronic bacterial skin infections in cats. Comp Contin Educ Pract Vet 21 (12), 1108-1115 VetMedResource.
  • Ihrke P J (1984) Therapeutic strategies involving antimicrobial treatment of the skin in small animals. J Am Vet Med Assoc 185 (10), 1165-1168 PubMed.
  • Thoday K (1981) Skin disease of the cat. Vet Rec 109 (21), 22-35 PubMed.

Other Sources of Information