Poisoning by Indigofera lespedezioides in horses.

The research article explores an instance of horse poisoning caused by the ingestion of the plant Indigofera lespedezioides in northern Brazil. The researchers suggest that indospicine, a compound present in the plant, is responsible for the toxic effects.

Research Objectives and Methodology

• This research was undertaken to understand the effects of Indigofera lespedezioides, a poisonous plant, on horses in Roraima, Brazil.
• To experimentally reproduce the disease, a 7-year-old horse was made to graze in a small enclosure overrun by the plant.
• The first signs of nervous deterioration were observed 44 days after the start of grazing.
• Both the experimental and a spontaneously infected horse were subjected to necropsies, however, no substantial gross lesions were found.

Findings

• Clinical manifestations of the poisoning included anorexia, sleepiness, unsteady movement, severe ataxia, weakness, stumbling, and progressive weight loss.
• The horses exhibited neuronal lipofuscinosis: accumulation of lipofuscin (a pigment formed due by the oxidation of lipids) in the brain, cerebellum, and spinal cord.
• Wallerian-type degeneration was observed in some tracts of the midbrain structures.
• Neuronal and axonal breakdown and lipofuscinosis were further confirmed through electron microscopy examination.

Conclusion and Implications

• The presence of indospicine was detected in four I. lespedezioides samples, while nitro toxins were only found in one.
• Considering the prevalence of indospicine and the scarcity of nitro toxins in the plant samples, the researchers inferred that indospicine was the toxic compound responsible for the poisoning.
• The effects of I. lespedezioides poisoning were found to be similar to those caused by Indigofera linnaei and Indigofera hendecaphylla varieties.
• This study raises awareness about the dangers of horse exposure to Indigofera lespedezioides and underlines the need for further research into the plant’s toxicity mechanics and potential preventive measures.