Epidemiological and immunological studies of sweet itch in horses in Israel.

The research examines the prevalence and factors affecting sweet itch in horses in Israel, underscoring the role of altitude, population density, horse type, and sensitivity to certain insect species. Also, the study utilized the ELISA technique to detect antibodies related to sweet itch in both normal and allergic horses.

Findings of the Research

• The research was based on a survey of horse owners in Israel, revealing that 21.8 per cent or 158 out of 723 horses showed signs of sweet itch, a common allergy in horses causing skin lesions.
• One of the outcomes of the study suggested a correlation between sweet itch and altitude. The chances of a horse contracting sweet itch showed a decline with increasing altitude. However, the study did not find any particular link between the condition and rainfall zones.
• The study also highlighted that the varied density of the horse population in different locations somewhat masked the altitude and rainfall observations.

Differences in Horse Sensitivity

• The study indicated that stallions were more susceptible to sweet itch compared to mares, indicating that gender could play a role.
• The researchers also found that pale horses seemed to have a lower sensitivity to sweet itch as opposed to dark horses. However, the number of dark horses in the sample was significantly smaller, meaning more research might be needed to substantiate this observation.

Sensitivity to Insect Extracts

• Both immediate and delayed reactions were observed in sensitive horses when they were given intradermal injections of extracts from Culicoides imicola and Stomoxys calcitrans.
• Delayed reactions were notable only with extracts of C imicola. Additionally, horses allergic to the condition also showed sensitivity to extracts of C circumscriptus.

Use of ELISA Technique

• Furthermore, the research employed the Enzyme-Linked Immunosorbent Assay (ELISA) technique, a common lab test, to reveal antibodies to extracts of Culicoides species and Stomoxys species in the blood of normal and allergic horses.