Critical and controlled tests of activity of a macrocyclic lactone (compound F28249-alpha) against natural infections in internal parasites of equids.

The research investigates the effectiveness of a new compound, F28249-alpha, in eliminating internal parasites in horses, ponies, and donkeys. The results showed a high rate of success in removing several types of parasites at different drug doses.

Methodology

• Researchers conducted thirteen ‘critical tests’ which largely focused on the ability of the compound to remove larger parasites. One of these tests also included benzimidazole-resistant small strongyles, a equine intestinal parasite.
• There were also four ‘controlled tests’ where the compound’s effectiveness was tested against more types of parasites, including stomach worms and lungworms.
• The experiments took place over a period ranging from 6 to 52 days, where the animals were euthanized post-treatment for further examination.
• The method of administration for F28249-alpha was via a stomach tube, administering different dosages ranging from 1 to 4 mg/kg body weight.

Results

• The study found F28249-alpha to be extremely effective with a 100% success rate in removing certain types of parasites, including mature Parascaris equorum, a type of roundworm; different life stages of Gasterophilus nasalis, stomach bot flies; and two species of large strongyles or bloodworms, namely Strongylus vulgaris and Strongulus edentatus.
• In the case of another type of stomach bot flies, Gasterophilus intestinalis in the stomach, the second stage larvae were removed at a rate of 88% at a dosage of 2 mg/kg. This rate increased to between 93% and 100% for dosages of 3 mg/kg or higher.
• However, removal rates were somewhat lower for the third stage larvae of this parasite, with mean removals ranging from 7% at a dosage of 1mg/kg to 98% at 3.5mg/kg.
• Additionally, the study observed that the release of G. intestinalis in feces, an indication of successful treatment, was often slow. This suggested that more effectiveness might have been noted had the researchers waited longer before performing the post-treatment examinations.

Conclusions

The research demonstrates the high efficacy of macrocyclic lactone compound F28249-alpha in the treatment of several types of equine internal parasites. This could potentially be a promising development in equine parasitic treatment, considering variable dosages and a longer time frame post-treatment. However, additional research is required to confirm these findings and to determine the appropriate dosage and treatment intervals for different types of parasites.