Ovine and Caprine Tetanus Study Guide

Overview and Clinical Importance

Tetanus (commonly called "lockjaw") is an acute, often fatal, infectious neuromuscular disease caused by the neurotoxin tetanospasmin produced by Clostridium tetani. This gram-positive, anaerobic, spore-forming bacterium is ubiquitous in soil and the gastrointestinal tract of herbivores. Small ruminants (sheep and goats) are among the most susceptible domestic species to tetanus, second only to horses and humans.

Tetanus is a vaccine-preventable disease that remains an important cause of mortality in unvaccinated or inadequately vaccinated small ruminant flocks. The disease is characterized by sustained muscle rigidity and spasms resulting from toxin-mediated blockade of inhibitory neurotransmitter release in the central nervous system. Understanding the pathophysiology, clinical presentation, and management of tetanus is essential for NAVLE success.

Etiology and Epidemiology

Causative Agent

Clostridium tetani is a gram-positive, obligate anaerobic, spore-forming rod measuring 0.3-0.6 micrometers in width and 3-12 micrometers in length. The characteristic morphology shows terminal spores giving the bacterium a distinctive "tennis racket" or "drumstick" appearance on Gram stain. The optimum growth temperature is 37°C, and growth requires strict anaerobic conditions.