Evaluation of the field efficacy of an avirulent live Lawsonia intracellularis vaccine in foals.

The research investigates the impact of a live vaccine for a disease called equine proliferative enteropathy in young horses, finding undefined preventative benefits, even though the rate of disease in the studied population decreased during the trial.

Background

• The article focuses on equine proliferative enteropathy, a disease in foals caused by a bacterium called Lawsonia intracellularis. This is a newly emerging disease and there haven’t been defined preventative measures or treatments for it yet.

Hypothesis and Methodology

• The researchers hypothesized that using a vaccine could help prevent both the clinical and sub-clinical manifestations of the disease.
• To test their hypothesis, the researchers conducted an experiment involving 202 foals from Central Kentucky. These were randomly split into two groups – the vaccinated and the non-vaccinated group.
• The vaccinated foals received an avirulent (non-disease causing), live Lawsonia intracellularis vaccine. They were administered this vaccine intra-rectally twice, with a 30-day gap in-between.

Monitoring and Evaluation

• The foals were closely monitored for signs of clinical disease. Their total solids and average weight gain were tracked until they grew to be yearlings.
• The study provided interesting results, the disease incidence on the farms involved in the study decreased overall, though it was found that this decrease did not significantly differ between the vaccinated and non-vaccinated groups.

Study Implications

• The decline in disease prevalence within the studied population during the trial might be an indirect effect of the vaccine trial conducted on the farms, as shown by the fact that disease prevalence in Central Kentucky remained unchanged in 2009 compared to the year before.
• However, the data isn’t conclusive enough to definitively establish the vaccine’s effectiveness, as both the vaccinated and non-vaccinated groups saw a similar decrease in disease incidence. More detailed and extended research is required to understand the impact of the Lawsonia intracellularis vaccine on equine proliferative enteropathy.