Suspected tremetol poisoning in horses

Area of Science:

• Veterinary Toxicology
• Equine Pathology
• Plant-Animal Interactions

Background:

• Overgrazed pastures can lead to livestock ingesting toxic plants.
• White snakeroot (Eupatorium rugosum) is a known toxic plant for livestock.
• Equine mortality events necessitate identification of underlying causes.

Purpose of the Study:

• To investigate the cause of death in horses from a specific herd.
• To determine the role of Eupatorium rugosum ingestion in the observed equine deaths.

Main Methods:

• Clinical observation of affected horses.
• Analysis of serum biochemistry (creatine kinase, aspartate transaminase, alkaline phosphatase).
• Postmortem histopathologic examination.
• Environmental assessment of pasture and plant identification.

Main Results:

• Four out of ten horses died within one week.
• Clinical signs included muscle tremors, ataxia, sweating, and myoglobinuria.
• Elevated serum enzyme activities were noted; histopathology was nonspecific.
• Eupatorium rugosum was identified as heavily browsed in the pasture.

Conclusions:

• Ingestion of Eupatorium rugosum is the suspected cause of mortality in these horses.
• Tremetone, a toxin from white snakeroot, likely contributed to the clinical signs and death.
• Pasture management and toxic plant awareness are crucial for equine health.