Research Assistant Professor Texas Tech University School of Veterinary Medicine Kapaau, Hawaii, United States
Abstract:
Background: Intradermal skin testing in horses is a complicated and time-consuming procedure in ambulatory settings. Few recommendations currently are available for the selection of time points to evaluate.
Objective: Compare the results of intradermal skin testing between 15 minutes and 30 minutes to identify the optimum time for observations in ambulatory settings.
Animals: 17 client-owned horses in Texas
Methods: All horses were clipped and prepped for intradermal skin testing of 23 allergens, 1 positive control (histamine), and 1 negative control (saline). Lesions sides were measured by the maximum diameter 15 minutes and 30 minutes post-injection. Saline ratio, histamine ratio, and severity were calculated for each lesion.
Results: Statistically significant differences in diameter were identified in 13/23 allergens; however, no statistical differences were found for the saline ratio, histamine ratio, or in severity (normal, mild, severe). 5/17 horses had a minimum of 4/23 positive allergens (either severe or mild) at 15 minutes that were normal by 30 minutes. 8/17 horses had a minimum of 4/23 normal allergens at 15 minutes that were positive (either severe or mild) by 30 minutes.
Conclusions and Clinical Importance: Further work is necessary to identify the relevance of temporal changes in lesions size when evaluating intradermal skin testing results. Evaluation of multiple time points may be useful for identifying positive allergens.
