Neurologic abnormalities and cerebrospinal fluid changes in horses administered fumonisin B1 intravenously.

This study evaluated the toxic effects of a toxin called fumonisin B1 when injected into the veins of horses. It investigated the dose-dependent impact, initial neurological symptoms, their progression, and changes in the brain fluid (cerebrospinal fluid) of the horses. The research is significant since it identified and quantified the degree of neurologic and fluid changes caused by the specific toxin, helping establish a safe dosage limit.

Research Methodology

• Seventeen healthy horses were used for the study and were divided into groups of different dose exposures.
• Each group was injected intravenously with different doses of purified fumonisin B1 (FB1) ranging from 0 to 0.20 mg.
• An observer, unaware of the dose groups, evaluated the horses for neurological abnormalities.
• Once the abnormalities reached severe levels, samples of the cerebrospinal fluid (CSF) were collected and evaluated.
• The CSF pressure, cell count, protein, albumin and glucose concentrations, and creatine kinase activity were all measured.
• The onset of neurological abnormalities and changes in CSF were compared between different doses using ANOVA, a statistical tool.

Key Findings

• Horses receiving a low dose of fumonisin B1 (0.01 mg/kg) and control group horses displayed no neurological changes.
• Horses subjected to higher doses of FB1 started showing initial clinical signs like hindlimb ataxia, delayed forelimb placement, and decreased tongue movement between the 4th and 10th day of exposure.
• As the study progressed, more severe symptoms such as depression, hyperesthesia (increased sensitivity to touch), and intermittent dementia also occurred.
• For FB1 doses between 0.05 and 0.20 mg/kg, mild clinical signs became significantly noticeable earlier than the severe clinical signs.
• Horses with neurological issues showed higher CSF protein, albumin, and IgG concentrations, indicating changes within the cerebrospinal fluid due to FB1 exposure.

Conclusions

• The study concluded that the injection of fumonisin B1 had dose-dependent neurologic and CSF changes. Exposure rates of 0.01 mg FB1/kg IV every 24 hours for 28 days were identified as the no-observable limit.
• The observed neurologic and CSF changes were consistent with vasogenic cerebral edema, a condition involving fluid leakage from the brain’s blood vessels leading to swelling.