Reactivity to intradermal injection of extracts of Dermatophagoides farinae, Dermatophagoides pteronyssinus, house dust mite mix, and house dust in dogs suspected to have atopic dermatitis: 115 cases (1996-1998)

Objective-To compare reactivities to intradermal injection of extracts of D ermatophagoides farinae, Dermatophagoides pteronyssinus, house dust mite mi x, and house dust in dogs suspected to have atopic dermatitis. Design-Retrospective study. Animals-115 dogs. Procedures-Records of ail dogs suspected to have atopic dermatitis that und erwent intradermal testing between October 1996 and July 1998 were reviewed . Reactivities to intradermal injection of crude mixed house dust mile (1:2 5,000 wt/vol) and crude house dust 125 PNU/ml) extracts were compared with reactivities to intradermal injection of individual extracts of D farinae a nd D pteronyssinus (1:50,000 wt/vol). Results-Ninety dogs were confirmed to have atopic dermatitis including 61 o f the 69 dogs with positive reactions to either or both of the individual h ouse dust mite extracts. Intradermal testing with the mixed house dust mite extract had sensitivity of 75%, specificity of 96%, and accuracy of 83%, I ntradermal testing with the house dust extract had sensitivity of 30%, spec ificity of 93%, and accuracy of 56%. Conclusions and Clinical Relevance-Results suggest that use of crude mixed house dust mite and crude house dust extracts for intradermal testing in do gs is not as accurate a method of determining house dust mite hypersensitiv ity as is the use of individual D farinae and D pteronyssinus extracts main ly because of the high percentage of false-negative results. Extracts of in dividual house dust mites are recommended for intradermal testing of dogs s uspected to have atopic dermatitis.