Flea Allergic Dermatitis

Also known as:

FAD, Flea Bite Hypersensitivity, FBH, Flea Dermatosis

Description

• Usually involves [[Skin Immunologic - Pathology#Type I

reactions|Type I reaction]] and [[Skin Immunologic - Pathology#Type IV reactions|Type IV reaction]] and cutaneous basophil hypersensitivity

• Mainly

dorsolumbosacral area involved, abdomen, caudomedial thighs, flanks, 

neck of cats

• Secondary trauma is self-inflicted
• Grossly:
  • Papular

dermatitis

• • Secondary excoriations
  • Alopecic nodule if

chronic

• Microscopically:
  • Hyperplastic superficial

perivascular dermatitis

• • Oedema, mast cells,

basophils, eosinophils, lymphocytes, histiocytes

• • Fibropruritic nodules

covered by hyperplastic epidermis

• Occurs in cats and dogs mainly
• Irritation caused by enzymes, anticoagulants and histamine-like substances
• Hypersensitivity to flea saliva may develop
• Young or small animals may suffer from aneamia
• Lesions normally in dorsolumbosacral region, caudomedial thighs, ventral abdomen, flank, neck (cats)
• Grossly:
  • Red papules and secondary excoriations
• Usually involves Type I reaction and Type IV reaction and cutaneous basophil hypersensitivity
• Mainly dorsolumbosacral area involved, abdomen, caudomedial thighs, flanks, neck of cats
• Secondary trauma is self-inflicted
• G

Diagnosis

Pathology

Grossly:

• • Papular dermatitis
  • Secondary excoriations
  • Alopecic nodule if chronic
• Microscopically:
  • Hyperplastic superficial perivascular dermatitis
  • Oedema, mast cells, basophils, eosinophils, lymphocytes, histiocytes
  • Fibropruritic nodules covered by hyperplastic epidermis