Efficacy of ivermectin in controlling Strongyloides westeri infections in foals.

This research study examines the effectiveness of a medication called ivermectin in controlling an infection by the Strongyloides westeri parasite in newborn horses (foals). Findings indicate that foals from treated mothers showed significantly less presence of S. westeri parasites, but no differences were observed in the severity of foal heat diarrhea between treated and untreated groups. Additionally, the treatment at a later stage (21 days old) was also effective in reducing the parasite count.

Methodology and Treatment Groups

• The researchers had a sample size of 63 foals for this study. These foals were divided into two main groups.
• One group consisted of 28 foals whose mothers had been treated with ivermectin on the day of giving birth. These doses were given intramuscularly (IM) with the given measure of 200 micrograms/kg of the dam’s body weight.
• The control group had 35 foals whose mothers were only administered the vehicle (inactive substance or placebo).

Assessment of Parasitic Infection and Diarrhea

• The study looked at the effect of ivermectin on the vertical transmission (from mother to offspring) of Strongyloides westeri. This was assessed by looking at the density of S. westeri eggs in the foals’ feces from the 17th day to the 28th day after birth.
• The researchers also monitored the incidence and severity of foal heat diarrhea, a common condition affecting newborn foals, often caused by bacterial infection, dietary changes or parasitic infestations.

Treatment of Foals and Results

• In a secondary experiment involving the same foals, they were treated directly with ivermectin intramuscularly. Thirty-two foals received the drug on the 21st day of their life, while 31 foals served as the control group.
• When tested from the 26th day to the 32nd day (end of trial), the ivermectin treated group had significantly fewer S. westeri eggs in their feces than those in the control group.

Overall Findings

• The ivermectin treatment appears to be effective in controlling Strongyloides westeri infections in foals. Significant drop in parasite presence was observed in foals whose mothers were treated just after birth, and in those who received the drug at the 21 days of their life.
• Though an effective parasitic control, ivermectin did not show any effect on the frequency or severity of foal heat diarrhea. Further research may be needed to find effective treatments for this common condition affecting foals.