Effectiveness of ivermectin against later 4th-stage Strongylus vulgaris in ponies.

The research investigates the effectiveness of a medicine called ivermectin in treating ponies infected with a parasite called Strongylus vulgaris. The drug showed a high success rate of nearly 99% in eliminating the parasites and resolving associated disease symptoms.

Research Process

• The researchers started with a group of twelve worm-free pony foals. The ponies were artificially infected with the Strongylus vulgaris parasite in a controlled environment.
• About 8 weeks after the inoculation, half of the ponies were treated with ivermectin. The medicine was administered intramuscularly (IM) at a dosage rate of 200 micrograms per kilogram of the pony’s body weight.
• The rest of the ponies were given a placebo to establish a control group for comparison.
• The research extended for over a month, with all the ponies being necropsied 35 days after starting the treatment.

Findings and Conclusion

• The effectiveness of ivermectin was calculated at 98.9%, as the drug nearly completely eradicated later 4th-stage S vulgaris larvae. These parasites were primarily located near the origin of major intestinal arteries of the foals.
• The medicine also showed effectiveness in reducing clinical signs of the parasitic infection and allowing the resolution of associated lesions due to verminous arteritis.
• The researchers further tested the efficacy of ivermectin on a pony foal that was reared on a pasture and had evidence of arteritis in some arteries. The drug showed a positive response in this case too: on subsequent arteriographs, there was noticeable regression of the lesion, and at necropsy 9 weeks post-treatment, no arteritis or larvae were found in the previously affected arteries.
• The high success rate of ivermectin against S vulgaris in ponies makes it a promising treatment for this parasitic infection in this equine population.