Intradermoreaction technique

ANAMNESIS FORM

Complete on line the interactif Animal Information Sheet.  Localise the lesions by using the typographe silhouette.

 

Intradermal Technique

Drug interference

In order to avoid false negative interpretations of the tests, it is necessary that no drugs capable of producing negative results have recently been administered to the animal.

Recommended delay before carrying out tests

Recommended delay before use of IDR

 

Corticoides
Oral (prednisone < 1 mg/kg)	less than 2 weeks wait 1 week
Oral on repeated occasions or at a high dose	wait 2 weeks
Topical on repeated occasions	wait 2 weeks
Slow release injectable	wait 6 weeks
Diagnosed Cushing’s disease	wait 6 weeks
Slow-release Projestogen
In all cases	wait 4 months
Anti-histamines
For the majority	wait 2 days
Astemizole	wait 2 months
Cetirizine, Loratadine	wait 1 week

Preparation of the animal

If a anaesthesia is necessary, all current options can be used (Rompun®, Imalgene®, Rapinovet®, Domitor® or Zoletil®).

Shave an area on the latero inferieur area of the thorax of the animal.

Intradermal reaction technique

Mark each site of injection using a felt-tipped pen

Inject 0.05 ml of each extract

Interpret the results after a period of 15 minutes.

Interpreting the tests (Test interpretation)

The tests can only be evaluated if the negative control provokes a non-erythematous papule of less than 5 mm in diameter and if histamine provokes an erythematous papule greater than 10 mm in diameter.

All erythematous reactions with a diameter greater than the average diameter of the two controls (histamine and negative control) are considered positive results.

Interpretation

 

The presence of a positive reaction indicates that the animal has a cutaneous sensitivity to the corresponding allergen. The inclusion of this allergen in a desensitisation protocol depends on the animal’s medical history and on the nature of the allergen.

 

Errors in the interpretation of intradermal reactions

False-negative default error results when interpreting intradermal reactions

• Drug interference
• Out-of-date extracts
• Contaminated extracts
• Subcutaneous injection
• Insufficient volume (air bubbles).

False-positive default error results when interpreting intradermal reactions

• Irritant extracts
• Contaminated extracts
• Volume injected > 0.05 ml
• Injection too close to positive control
• Cross-reactions between mites: false-positive reactions to Dermatophaoides extracts due to the presence of sarcoptic, otodectic or trombicular mange
• Dermographism (particularly in the Shar Peï, a positive reaction at the site of injection of the negative control)
• Haemorrhage.

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