Aggregate risk study of exposure to endophyte-infected (Acremonium coenophialum) tall fescue as a risk factor for laminitis in horses.

The research investigates the link between exposure to endophyte-infected tall fescue (a type of grass) and the development of laminitis, a debilitating condition, in horses. The study suggests a potential risk associated with the exposure to the infected grass, but further detailed studies are required to confirm this hypothesis.

Research Subject and Objective

• This study focuses on the potential risk factor for the development of laminitis in horses, particularly looking at their exposure to endophyte-infected tall fescue (EITF).
• Endophyte-infected tall fescue contains loline and ergot alkaloids, which are known to cause vasoconstriction (narrowing of the blood vessels) in the horses’ body.
• The key objective of this research was to examine the potential correlation between the horses’ exposure to EITF and their development of laminitis.

Methodology

• An aggregate risk study was used to evaluate the assumed correlation.
• The researchers grouped the Veterinary teaching hospitals participating in the Veterinary Medical Data Base by whether horse admissions were likely to have been at high, moderate, or low risk for exposure to EITF.
• The data collected from the Veterinary Medical Database covered the years from 1980 to 1990 and included 185,781 admissions, from which 5,536 horses were diagnosed with laminitis.

Results

• The analysis showed that the proportion of horse admissions with laminitis was highest in the group with the highest risk of exposure to EITF.
• There were 3.41, 3.04, and 2.00 cases of laminitis per 100 admissions for the high, moderate, and low-risk groups, respectively, indicating a possible correlation between the exposure to EITF and the onset of laminitis.
• The comparisons of laminitis incidents in high- and moderate-risk groups with the low-risk group revealed significant statistical differences both across all months and within individual months.

Interpretation and Conclusion

• The researchers suggested that if the difference among risk groups is attributed entirely to exposure to EITF, the population-attributable risk is 7 cases per 1,000 admissions, or 15% of all admissions for laminitis at veterinary teaching hospitals in the data base.
• However, they emphasized that these are preliminary data, and while they provide support to the theory of EITF exposure being a risk factor for laminitis, additional studies at the individual animal level are necessary to definitively confirm this hypothesis.