Comparing the effectiveness of four antihistamines with olopatadine in healthy Thoroughbred horses.

The research conducted a comparative study on the effectiveness of four new antihistamines in contrast to olopatadine in treating allergic reactions in Thoroughbred horses, and found that levocetirizine might exhibit an antihistamine effect equivalent to olopatadine.

Methodology

• The study involved six healthy Thoroughbred horses that were administered with five different antihistamines, including olopatadine, levocetirizine, bilastine, rupatadine, and desloratadine.
• These medications were given orally in varying amounts (ranging from 50 mg to 200 mg) over intervals greater than two weeks.

Measurement and Comparison

• In order to evaluate the effectiveness of these medications, the researchers relied on measurement of the wheal area induced by an intradermal injection of histamine.
• The rate of wheal inhibition, comparatively with positive and negative controls, was further used as the determining factor for the antihistamine effects of these medications.

Results

• The study revealed that olopatadine yielded an average maximum wheal inhibition rate of 85.3% – highest among the tested antihistamines, except for levocetirizine.
• Levocetirizine matched or possibly even slightly surpassed olopatadine with a rate of 85.4%.
• As per these findings, it was concluded that levocetirizine could have an equally potent antihistamine effect on horses as olopatadine.
• The study also found bilastine, rupatadine, and desloratadine to show less significant wheal inhibition rates of 51.1%, 55.3%, and 59.8% respectively.

Conclusion

• Overall, the study offers important insights into the comparison of the effectiveness of different antihistamines on horses.
• While olopatadine remains an effective treatment, the study reveals levocetirizine as another potential antihistamine to be considered for treating allergic reactions in horses.