Equis ISSN 2398-2977

Dermatology: intradermal test

Synonym(s): Skin test, Intradermal allergy test

Overview

  • Reaction to a local injection of antigen is used as a test for hypersensitivity in order to formulate allergen-specific immunotherapy (hyposensitization) and/or to begin avoidance of the offending antigens.

Sampling

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Tests

Methodologies

  • Sedation may be required   Anesthesia: standing chemical restraint  . Xylazine   Xylazine   or detomidine   Detomidine hydrochloride   are most commonly used.
  • An area over the lateral neck 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 with histamine and saline used as positive and negative controls, respectively.
  • Compound 48/80 can be used as an alternative to histamine for the positive control.
  • Test is typically read at 15 min, 4-6 h, and 24 h in order to determine both early and late-phase reactions.

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.

Validity

Validity

Sensitivity

  • 66-90%.

Technique (intrinsic) limitations

  • A positive intradermal skin test indicates that animal has skin sensitizing antibody   Dermatology: intradermal test  .

A positive test does not necessarily mean that the allergen is clinically significant in that animal.

  • Completely negative results are usually because the tentative diagnosis of atopy was incorrect.
  • False positives: may occur if very irritable, inflamed or traumatized test site.
  • False negatives: if drug interference, eg glucocorticoids, anti-histamines; inherent host factors, eg serious internal disease; 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  • Insufficient allergenic principle, eg outdated extract, may give false negative results.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lorch G et al (2001) Results of intradermal tests in horses without atopy and horses with atopic dermatitis or recurrent urticaria. Am J Vet Res 62 (7), 1051-1058 PubMed.
  • Jose-Cunilleras E (2001) Intradermal testing in healthy horses and horses with chronic obstructive pulmonary disease, recurrent urticaria or allergic dermatitis. JAVMA 219 (8), 1115-1121 PubMed.
  • Shipstone M (1999) The use of compound 48/80 as a positive control in equine intradermal allergy testing. Vet Derm 10 (4), 291-295.
  • Tallarico J et al (1998) Results of intradermal allergy testing and treatment by hyposensitization of 64 horses with chronic obstructive pulmonary disease, urticaria, headshaking and/or reactive airway disease. Vet Allergy Clin Immunol (1), 25-35.
  • Delger J M (1997) Intradermal testing and immunotherapy in horses. Vet Med. 635-639.
  • McGorum B C et al (1993) Evaluation of intradermal mold antigen testing in the diagnosis of equine chronic obstructive pulmonary disease. Equine Vet J 25 (4), 273-275 PubMed.
  • McGorum B C et al (1992) Preliminary observations on inhalation and intradermal challenges of horses with oil seed rape. Vet Rec 131 (8),163-167 PubMed.
  • Evans A G et al (1992) Intradermal testing of horses with chronic obstructive pulmonary disease and recurrent urticaria. Am J Vet Res 53 (2), 203-208 PubMed.
  • Fadok V A et al (1990) Equine insect hypersensitivity- skin test and biopsy results correlated with clinical data. Equine Vet J 22 (4), 236-240 PubMed.
  • DeBoer D J et al (1989) Survey of intradermal skin testing practices in North America. JAVMA 195 (10), 1357-1363 PubMed.

Other sources of information

  • Willemse T & von Tscharner C (1998) Eds. Advances in Veterinary DermatologyProc 3rd World Congress Vet Derm, Edinburgh. Butterworth-Heinemann, UK.


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