Felis ISSN 2398-2950

Skin: intradermal test

Contributor(s): Rosanna Marsella, Ian Mason, Catherine Fraser

Overview

  • Identify potentially important allergens in order to start immunotherapy once a diagnosis of atopy Skin: atopic dermatitis has been made.

Sampling

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Tests

Methodologies

  • Skin testing is performed with cats in lateral recumbency usually with the use of sedation, eg medatomidine Medetomidine or ketamine Ketamine /diazepam Diazepam will not interfere with interpretation.
  • An area over the lateral trunk is clipped.
  • Injection sites are marked with a felt-tip marker.
  • 0.05 ml of each of a panel of allergens is injected into the dermis using an insulin type syringe and 24-26 G needle with histamine and saline used as positive and negative controls respectively.
  • Injection sites are examined for 15-30 minutes post injection but should be observed continuously during this period.

Availability

  • Intradermal skin testing is available by referral to a veterinary dermatologist.
    Intradermal skin test panels are available but testing and interpretation should only be undertaken by experienced practitioner.
  • The types and concentrations of allergens used for testing dogs are similar to and acceptable for testing cats.

Technique (intrinsic) limitations

  • A positive intradermal skin test indicates that animal has skin sensitizing antibody   Atopy: positive intradermal skin test  .
    A positive test does not necessarily mean that the allergen is clinically significant in that animal.
  • False-positives: may occur if very irritable, inflamed or traumatized test site, or surface skin contamination.
  • False-negatives: if drug interference, inherent host factors, eg serious internal disease, or (possibly) testing at the wrong time of year.

Technician (extrinsic) limitations

  • Poor skin test technique may give false-negative or false-positive results.
  • Irritant allergens may give false-positive results.
  • Insufficient allergenic principle, eg outdated extract may give false-negative results.
  • Recent medication may give false-negatives.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Chalmers S A & Medleau L (1994) Feline atopic dermatitis. Its diagnosis and treatment. Vet Med 89, 342.
  • Foster A P & O'Dair H (1993) Allergy testing for skin disease in the cat. In vivo vs in vitro tests. Vet Dermatol 4, 111.
  • McDougal B J (1986) Allergy testing and hyposensitization for three common feline dermatoses. Mod Vet Pract 67, 629.
  • Reedy L M (1982) Results of allergy testing and hyposensitization in selected feline skin diseases. JAAHA 18, 618.

Other sources of information

  • Reedy L M, Miller W H & Willemse J R (1997) Allergic skin diseases of dogs and cats. 2nd edn. Philadelphia: W B Saunders. pp 103-109. (Detailed procedure and interpretation.)
  • Moriello K A & Mason I S (1995) Handbook of Small Animal Dermatology. Eds K A Moriello & I S Mason. 1st edn. Pergamon. pp 33-36. (Concise step-by-step procedure.)
  • Scott D W, Miller W H & Griffin C (1995) Miller and Kirk's Small Animal Dermatology .Eds D W Scott, W H Miller & C Griffin. 5th edn. Philadelphia: W B Saunders Co. (Concise step-by-step procedure).
  • Chalmers S et al(1991) Clinical evaluation of intradermal skin testing in cats. Proc Assoc Vet Allergy.West Palm Beach, FL, USA. p14.


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