Development of a novel in vitro equine anthelmintic assay.

The research article presents the development of a new laboratory method that uses horse parasites and a micromotility meter to test the effectiveness of worm treatments for horses.

Introduction and Methodology

• The study introduces a novel in vitro (lab-based) assay or test. In this assay, the researchers use a horse parasite known as Strongylus edentatus along with a micromotility meter, which is a device for measuring small movements.
• The aim of the test is to measure the anthelmintic activity or effectiveness of different drugs used for treating worm infestations in horses.
• The researchers tested the anthelmintic activity of three commercially available worm treatments for horses (dichlorvos, ivermectin, and pyrantel pamoate), as well as an experimental drug (p-toluoyl chloride phenylhydrazone).
• These drugs were evaluated at four different concentrations, and the effects were observed over a 24-hour incubation period.

Results

• The research found that when the drugs were used at concentrations greater than or equal to 10 micrograms/ml, all four treatments significantly reduced the motility or movement of the Strongylus edentatus larvae, thus indicating their anthelmintic activity.
• When used at a concentration of 1 microgram/ml, pyrantel pamoate was still effective in reducing motility. However, the experimental drug, hydrazone, increased movement at this concentration, which implies it may not be effective or could even stimulate the parasites in actual practice.
• At the lowest concentration level of 0.1 micrograms/ml tested, none of the treatments reduced motility significantly. In fact, dichlorvos was observed to increase larval motility at this concentration.

Extended Observations

• On extending the incubation period to 48 hours, two drugs – ivermectin and pyrantel pamoate, were effective at a lower concentration of 1 microgram/ml, reducing the motility of the larvae. Dichlorvos and the hydrazone drug, however, only had a noticeable effect at a concentration of 10 micrograms/ml or higher.
• At the lowest test concentration (0.1 microgram/ml), and after 48 hours of incubation, none of the treatments significantly reduced motility. But two treatments – dichlorvos and the hydrazone drug, resulted in increased motility at this low concentration.

Study Implications

• This newly developed assay was found to be sensitive, accurate, and rapid, making it a potential valuable tool for testing the effectiveness of worm treatments for horses.
• Such an assay could also be used to identify new potential anthelmintics, monitor worm resistance to current drugs and even help understand the behavior and specific mode of action of these drugs.