Camelidae and Cervidae Endophyte Toxicity – NAVLE Study Guide

Overview and Clinical Importance

Endophyte toxicity represents a significant cause of neurological disease in grazing camelids and cervids. Endophytic fungi live symbiotically within certain pasture grasses, primarily tall fescue (Festuca arundinacea) and perennial ryegrass (Lolium perenne), producing mycotoxins that are beneficial to the plant but toxic to livestock. These toxicoses manifest as distinct clinical syndromes affecting the nervous system, thermoregulation, and peripheral circulation.

Camelids (llamas and alpacas) appear to be more susceptible to certain endophyte toxicoses than cattle or sheep, making recognition and prevention particularly important in camelid practice. Understanding endophyte toxicity is essential for NAVLE preparation as it encompasses toxicology, neurology, and herd health management principles.

Etiology and Pathophysiology

The Endophyte-Grass Relationship

Endophytes are fungi that live entirely within plant tissues without causing visible disease to the host plant. The relationship is mutualistic: the fungus receives nutrients and shelter, while the plant gains enhanced drought tolerance, insect resistance, and competitive advantage. Unfortunately, many alkaloids produced by these fungi are toxic to grazing mammals.