Association between forage mycotoxins and liver disease in horses.
Authors: Durham Andy E
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Association between forage mycotoxins and liver disease in horses Unexplained liver disease outbreaks in horses remain a significant clinical challenge, yet the contribution of forage contamination to these cases has never been systematically investigated. Durham's case–control study examined 29 premises with concurrent liver disease in four or more horses alongside 12 control premises, subjecting all forage samples to liquid chromatography/mass spectrometry analysis for 54 different mycotoxins. Whilst mycotoxin detection rates were similar between case and control premises (79% and 83% respectively), ten mycotoxins with established hepatotoxic properties—including fumonisin B1, aflatoxins B1 and G1, zearalenone, and various trichothecenes—appeared exclusively in case samples; fumonisin B1 concentrations were significantly elevated on diseased premises (median 0–81.7 μg/kg versus 0 μg/kg; P = 0.04). These findings provide epidemiological support for mycotoxicosis as a differential diagnosis in multi-horse liver disease presentations, particularly when specific contaminating agents such as fumonisins are detected. Given that forage testing remains uncommon in outbreak investigations, practitioners should consider targeted mycotoxin analysis—especially for fumonisin and other known hepatotoxins—when evaluating clusters of hepatic dysfunction, and prioritise feed management and storage assessment as part of their diagnostic approach.
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Practical Takeaways
- •Test forage from premises experiencing unexplained liver disease outbreaks for mycotoxins, particularly fumonisin B1, as these may be contributing factors even when overall mycotoxin levels appear acceptable
- •Recognize that the presence of mycotoxins in forage does not automatically indicate a problem (83% of control farms had mycotoxins), but specific toxins or combinations may be pathogenic—focus on fumonisin B1 and hepatotoxic compounds
- •Consider forage quality and mycotoxin analysis as part of diagnostic workup for cluster cases of liver disease, alongside traditional diagnostics and management assessment
Key Findings
- •Mycotoxins were detected in 79% of case premises and 83% of control premises (P > 0.99), showing no significant overall association between mycotoxin presence and liver disease outbreaks
- •Ten specific mycotoxins including fumonisin B1, deoxynivalenol, zearalenone, and aflatoxins were found exclusively at case premises
- •Fumonisin B1 concentration was significantly higher in case samples (median 0 μg/kg, IQR 0-81.7) versus control samples (median 0 μg/kg, IQR 0-0; P = 0.04)
- •Multiple hepatotoxic mycotoxins alone or in combination were identified exclusively at case premises, supporting forage mycotoxicosis as a potential cause of equine liver disease outbreaks