The ‘emergency’ back up tetanus antitoxin (TAT) dose, given to unvaccinated horses with high exposure risk, may be insufficient in the face of incubating infection. 

A TAT provides protection for less than 14 days and should be repeated in 7 days in high risk cases (e.g. complicated wound healing).

A recent review of evidence-based guidelines for tetanus prophylaxis was released at this year’s NZVA conference,  broken down by different classes of horses.

Following is a simplified approach:

• Unvaccinated adults (over 12 months): 

3 doses: 1st and 2nd doses 4-6 weeks apart, then 3rd dose within 12 months. Booster doses within 5 years after that, UNLESS the horse suffers a risk event.

• Vaccinated adults (over 12 months) suffering a risk event:

A toxoid booster should be administered if the horse suffers a risk event if it has been more than 12 months since the last toxoid booster.

• Unvaccinated horses over six months of age suffering a risk event:

When an unvaccinated horse, or a horse with an unknown history, suffers a risk event, the horse should be administered a tetanus toxoid dose and a tetanus antitoxin to provide immediate passive immunity.

2nd and 3rd follow up booster doses should be administered at the correct timing.

• Unvaccinated pregnant broodmares:

All mares intended for breeding should receive a complete tetanus vaccination primary protocol as per the first point. 

If a broodmare is pregnant and unvaccinated, she should be administered the first two doses 4-6 weeks apart during gestation, ideally starting no later than the eighth month of pregnancy. The third dose should be given within 12 months of the second dose.

• Vaccinated pregnant broodmares:

These mares should receive a toxoid booster 4-8 weeks prior to their due date. This ensures adequate transfer of passive immunity to the newborn foal via colostrum.

• Foals born to vaccinated dams:

If a foal has had adequate colostrum, documented by IgG levels, they do not require a TAT after birth. Their first toxoid dose should be given at 6 months of age, 2nd dose 4-6 weeks later and the 3rd dose within 12 months of the second dose, and every 5 years after that.

• Foals born to unvaccinated dams:

A TAT is advised to be given at birth. The tetanus toxoid primary course can be started at 3 months old. Due to the foal being under 6 months, it is recommended that three initial doses 4-6 weeks apart should be given, followed by a fourth within 12 months of the third.

Please phone the clinic to book your horse in for their tetanus vaccine today.