Flea Allergic Dermatitis

Also known as:

FAD, Flea Allergy Dermatitis, Flea Bite Hypersensitivity, FBH, Flea Dermatosis

Description

Cat Flea - August La Roux 2007, Wikimedia Commons

Flea allergic dermatitis is the most common skin disease of dogs and cats worldwide. Cases are caused by flea infestation, mainly by Ctenocephalides felis, the cat flea, but Ctenocephalides canis, Archaeopsylla erinacei, Spylopsyllus cuniculi and Pulex irritans can also be found on cats and dogs. Fleas are blood sucking, wingless insects that live and breed in the hair coat of an animal and often cause pruritis and annoyance. The term flea allergic dermatitis refers to the condition that arises due to hypersensitivity to flea saliva. Flea saliva also contains irritant components that contribute to the disease.

Signalment

Dogs and cats of any age may be afflicted by flea allergic dermatitis.

Diagnosis

Clinical Signs

• 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

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

• Microscopically:
  • Hyperplastic superficial

perivascular dermatitis

• • Oedema, mast cells,

basophils, eosinophils, lymphocytes, histiocytes

• • Fibropruritic nodules

covered by hyperplastic epidermis