Horses' rejection behaviour towards the presence of Senecio jacobaea L. in hay.
Authors: Sroka Louisa, Müller Clara, Hass Marie-Lena, These Anja, Aboling Sabine, Vervuert Ingrid
Journal: BMC veterinary research
Summary
# Editorial Summary Ragwort (*Senecio jacobaea*) poses a significant toxicological risk to horses through its pyrrolizidine alkaloid content, capable of causing acute hepatic failure at high doses or progressive liver damage with chronic low-level exposure. Sroka and colleagues investigated whether horses possess the sensory discrimination to actively reject ragwort-contaminated hay when offered ad libitum, testing six warmblood geldings (mean age 15 years) against hay deliberately contaminated at 5% and 10% ragwort levels; contaminated hay was presented for limited periods throughout the day alongside free access to clean forage, with investigators documenting rejection behaviour and withdrawing any horse that ingested ragwort plants on two separate occasions. Remarkably, all six horses demonstrated consistent rejection of ragwort regardless of contamination level, suggesting horses can reliably identify and avoid *Senecio jacobaea* through sensory cues—a finding with substantial implications for pasture and hay management protocols. This capacity for active avoidance indicates that ragwort toxicity in horses may primarily result from inadequate sorting opportunities (such as poor-quality hay or mixed feed) rather than an inability to discriminate the plant itself. For practitioners, these results support the case for maintaining strict hay quality standards and visual inspection protocols, whilst also questioning whether previous cases of ragwort poisoning reflect failures in feed management rather than equine sensory limitation.
Read the full abstract on PubMed
Practical Takeaways
- •Horses can naturally avoid ragwort in hay through sensory discrimination, but relying on this behaviour is risky—ensure hay is clean at source rather than depending on horses to sort contaminated forage
- •Individual variation in rejection behaviour means some horses may fail to avoid toxic plants; vigilant inspection and prevention of ragwort contamination is essential for herd safety
- •Ad libitum feeding does not guarantee horses will avoid toxic plants consistently enough to prevent chronic low-dose exposure and hepatic damage
Key Findings
- •Adult horses demonstrated selective rejection behaviour towards Senecio jacobaea contaminated hay when fed ad libitum
- •Horses were able to sort and avoid plant material at 5% and 10% contamination levels
- •Exclusion criteria based on ingestion of two plants twice at different timepoints suggests variable individual tolerance or recognition