Clinicopathologic study of horses surviving pyrrolizidine alkaloid (Senecio vulgaris) toxicosis.

This research investigates the impact of pyrrolizidine alkaloid, a toxin found in the plant Senecio vulgaris, on horses. The study monitors the blood of horses who ingested this toxin over a 14 month period, observing changes in their liver and assessing various enzymes and chemicals in their blood. The results suggest that long-term exposure leads to progressive liver damage, and while horses appeared healthy 14 months after exposure, they struggled with physical stress.

Objective of the Research

• The main aim of this research was to study the damaging effects of pyrrolizidine alkaloid toxicity (from ingestion of Senecio vulgaris) on horses’ health, particularly its impact on the liver.

Research Methodology

• Twenty horses of various ages were found to have eaten hay contaminated with Senecio vulgaris.
• From these horses, blood was collected monthly for the first seven months, then again in the ninth and fourteenth months after initial exposure.
• The blood was then tested for count and levels of several serum enzymes and chemical items, including aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyl transferase, sorbitol dehydrogenase, total bilirubin, BUN, glucose, cholesterol, inorganic phosphate, calcium, total protein, and albumin.
• Additionally, the amino acid profiles, conjugated bile acids, sulfobromophthalein clearance times were noted for each horse.
• A series of liver biopsies were also performed to observe histopathologic changes.

Research Findings

• Examination of the histopathologic changes in the liver revealed a worsening of lesions over time, indicating progressive liver damage.
• Amino acid ratios and aspartate aminotransferase suggested chronic liver degeneration, pointing to a long-lasting impact on the liver due to the toxin (statistically significant at the 0.05 level).
• The levels of gamma-glutamyl transferase, lactate dehydrogenase, and BUN fluctuated but eventually returned to the reference values or the normal levels.
• Even though the horses appeared clinically normal 14 months after the toxic exposure, they were unable to comfortably handle exercise-related stress, suggesting persistent, systemic damage.