The toxicity of phomopsin for sheep

Area of Science:

• Veterinary Toxicology
• Animal Science
• Pharmacology

Background:

• Phomopsin is a toxin produced by Phomopsis spp.
• Sheep are susceptible to phomopsin poisoning, affecting liver function.
• Understanding toxicity is crucial for managing livestock health.

Purpose of the Study:

• To determine the toxicity of pure phomopsin in sheep.
• To compare toxicity via subcutaneous (SC) and intraruminal (IR) administration.
• To identify factors influencing phomopsin toxicity, including dose and administration route.

Main Methods:

• Administration of pure phomopsin to Merino x Border Leicester wethers.
• Single SC and single/multiple IR injections were used.
• Clinical, biochemical, and histological assessments were performed.

Main Results:

• SC LD50 approximated 10 µg/kg.
• IR toxicity varied with dose size and frequency; 1000 µg/kg single IR dose mimicked SC toxicity.
• Daily IR doses of 50 or 200 µg/kg were lethal; 500 µg/kg single IR caused liver damage but no death.
• Inappetence was the earliest toxicity sign; individual susceptibility varied by ~10%.

Conclusions:

• Phomopsin toxicity is dose-dependent and influenced by administration route (IR > SC).
• Absorption rates and liver repair capacity modulate toxicity.
• Inappetence is a sensitive indicator; individual sheep exhibit varied susceptibility.