Health assessment of Tokara horses on Nakanoshima island: potential chronic hepatic dysfunction induced by Leopard plant (Farfugium japonicum) ingestion.

We investigated the health of Tokara horses (n=34) on Nakanoshima as part of conservation efforts for this breed. Although the horses were clinically healthy, elevated white blood cell count, neutrophil count and gamma-glutamyl transferase (GGT) levels were observed, leading to suspicion of chronic hepatic dysfunction and infectious disease. A survey revealed that the caretakers had been feeding the horses Leopard plant, which contains toxic pyrrolizidine alkaloids (PAs). The abnormal GGT levels observed in these horses may suggest the possibility of chronic PA poisoning resulting from the consumption of this plant. These findings suggest that raising awareness of poisonous plants and carefully managing plant species in grazing areas could enhance the conservation of native horse breeds.