Protection of yearling ponies against Strongylus vulgaris by foalhood vaccination.

This study is about the effectiveness of a vaccine in protecting young ponies against a common parasitic infection. The vaccine was administered during the foals’ first weeks of life, and its protective effects were evaluated after the ponies were intentionally exposed to the parasite months later.

Research Design and Methodology

• The experiment involved a group of mares and their foals, which were split into two main groups: those regularly treated with the anti-parasitic drug ivermectin, and those left untreated.
• Half of the foals in each group were vaccinated against Strongylus vulgaris, a common equine parasite, when they were 8 to 10 weeks old.
• The foals were then left to grow on separate pastures, away from their mothers, and, when they were 8 to 10 months old, they were moved into box stalls.
• At this point, half of the ponies in each treatment group were intentionally infected with S. vulgaris to test the effectiveness of the vaccination.

Key Findings

• The researchers observed that the ivermectin-treated, non-vaccinated ponies that were exposed to the parasite showed typical symptoms of acute verminous arteritis, a serious parasitic disease that can block blood vessels.
• However, the ivermectin-treated, vaccinated ponies did not show these symptoms, had significantly fewer arterial lesions (tissue damage caused by the parasite), and had 89% fewer parasites in their arteries according to post-mortem examinations.
• The study found no significant differences in terms of clinical symptoms, arterial lesions, or the number of arterial parasites between vaccinated and non-vaccinated foals that had not been treated with ivermectin.

Conclusions

• The results suggest that the vaccine can effectively protect ponies from S. vulgaris if it is administered early in life and combined with regular treatment with ivermectin.
• However, the vaccine may not be as effective in animals that have not been treated with ivermectin.