Efficacy of ivermectin in the oral paste formulation against naturally acquired adult and larval stages of Parascaris equorum in pony foals.

The research paper presents a study that investigated the effectiveness of ivermectin oral paste formulation, when given at a dosage of 200 micrograms/kg, against Parascaris equorum, a horse parasite, in pony foals.

Study Context and Methodology

• The study was a controlled experiment that involved twenty pony foals, aged 18 to 27 weeks, naturally infected with Parascaris equorum.
• The foals were divided into two groups and were kept in dry lots to control their environment.
• One group of foals was given ivermectin on the first day of the study.
• At two and five weeks after treatment (WAT), half of each group was necropsied to examine the presence of parasites in their small intestines and lung tissues.

Effectiveness of Ivermectin

• Ivermectin was found to be 100% effective against adult P equorum, which suggests a full elimination of the adult parasites from the treated foals.
• At 2 weeks post-treatment, it was revealed that ivermectin was completely effective against P equorum larvae in the lungs and 91% effective against the intestinal larvae.
• Overall, the effectiveness of ivermectin against all stages of intestinal P equorum was 93%.

Reinfection and Histologic Observations

• At 5 weeks post-treatment, the intestinal and lung larval populations were similar in both treated and untreated foals. This suggests that the treated foals had been reinfected from their environment peaking between 2 to 5 weeks post-treatment.
• The researchers also observed apparent increases in lymphoproliferative and inflammatory tissue reactions in the lung and liver tissues of treated foals.

Clinical Observations and Weight Gains

• No noticeable differences in clinical conditions were observed between the treated and untreated groups.
• However, the foals in the group treated with ivermectin had the most significant weight gains after treatment, indicating potential health improvements post-treatment.