Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.
Authors: Gröndahl G, Berglund A, Skidell J, Bondesson U, Salomonsson M
Journal: Equine veterinary journal
Summary
# Editorial Summary Swedish researchers have identified hypoglycin A (HG) — a toxic alkaloid — in the blood of horses affected by atypical myopathy (AM) and in sycamore maple (*Acer pseudoplatanus*) plant material from their grazing environments, providing the first direct evidence linking this compound to the disease. Using advanced chromatography techniques, the team sampled blood from affected and clinically healthy horses on two farms during an AM outbreak in May 2014, repeated sampling one month after the horses were relocated, and analysed plant material simultaneously for HG content. HG was detected not only in the two clinically affected horses but also in 20 of 22 asymptomatic co-grazers, with persistent low-level positivity in some animals a month after moving to clean pastures; notably, control horses from unaffected farms tested negative, and HG was found exclusively in sycamore maple, not Norway maple (*Acer platanoides*). These findings establish a clear epidemiological link between sycamore exposure and AM risk, suggesting that clinicians should maintain heightened suspicion for AM during spring and early summer when sycamore seeds and seedlings are abundant, whilst farriers and handlers should alert owners to remove or fence off sycamore trees from grazing areas — particularly given the persistent toxin exposure demonstrated even in asymptomatic horses.
Read the full abstract on PubMed
Practical Takeaways
- •European sycamore maple (Acer pseudoplatanus) should be identified and managed in pastures where atypical myopathy has occurred, as it contains hypoglycin A which is associated with the disease
- •Horses grazing pastures containing sycamore maple may accumulate HG in blood even without showing clinical signs; monitor at-risk herds during spring months when plant material is most available
- •Removal of horses from affected pastures may not immediately clear HG from circulation, so continued monitoring is warranted after relocation
Key Findings
- •Hypoglycin A (HG) was detected in blood samples from 2 horses with clinical atypical myopathy and 20 out of 22 co-grazing clinically healthy horses
- •HG was detected in plant material from Acer pseudoplatanus (European sycamore maple) but not from Acer platanoides (Norway maple)
- •One month after horses were moved to other pastures, a surviving case horse and 9 out of 20 previously positive co-grazing horses remained positive for HG
- •Control horses from unaffected farms were negative for HG, suggesting pasture exposure as the source