Tetanus is a deadly disease caused by Clostridium tetani, which is commonly found in soil, manure, and the environment horses frequent. Due to their sensitive nature to the tetanus neurotoxin, horses are at significant risk for infection through wounds, surgeries, or abscesses.
How Tetanus Affects Horses
When Clostridium tetani enters the body, the bacteria produce toxins that affect the nervous system, leading to painful muscle spasms, stiffness (commonly known as “lockjaw”), and in many cases, death. Since tetanus isn’t contagious, cases often appear sporadically but can be fatal, particularly in unvaccinated horses.
The Importance of Vaccination
Vaccinating your horse is the most effective way to protect them against tetanus. In New Zealand and Australia, a primary immunization protocol involves three doses of tetanus toxoid (TT) for horses over 6 months of age, followed by regular boosters every 5 years to maintain immunity. Horses less than 3 months old rely on passive immunity transferred from their vaccinated mothers or tetanus antitoxin (TAT) if maternal vaccination is unknown.
Vaccination Schedule
- Foals: Begin a four-dose series of vaccinations starting between 3 and 6 months old if the mare was vaccinated. In unvaccinated foals or those born to unvaccinated mares, passive immunity via antitoxin and a four-dose TT protocol should be implemented.
- Adult Horses: Horses older than 6 months require three doses of TT, spaced 4–6 weeks apart, followed by boosters every 5 years.
- Horses at Risk: In case of a high-risk event (e.g., injury, surgery), unvaccinated horses should receive both TT and TAT for immediate protection, with continued boosters to ensure lasting immunity.
Special Considerations for Mares and Foals
Pregnant mares should receive a booster dose of TT 4–8 weeks before foaling to ensure the transfer of passive immunity to their foals through colostrum. This passive immunity protects foals up to 6 months old, but foals with low immunity levels or born to unvaccinated mares should receive plasma transfusions or antitoxin after birth to prevent tetanus infection.
Conclusion
Tetanus is a severe, often fatal disease that is preventable with proper vaccination. Consult your veterinarian to ensure your horse is up to date on its tetanus vaccination schedule and adequately protected against this life-threatening disease.
