Tetanus Death Review Finds Correlation to Age, Vaccination Status

Young horses are more susceptible to the dangers of tetanus than their older counterparts and are at a greater risk of death due to the disease, according to recent study carried out by Belgian researchers at the University of Liege.

Their research also revealed that, contrary to a common belief, the administration of tetanus anti-serum (TAT) is not 100% effective in preventing tetanus, said Gaby van Galen, DVM, MSc, primary author of the study, which was published recently in a Dutch veterinary health review.

Tetanus is caused by an anaerobic bacteria found in the soil and in feces. It infects horses through wounds. Clinical signs include spasms, stiffness, anxiety, perspiration, extended neck and head, prolapse of the third eyelid, retracted lips, and an elevated tail. Horses that have difficulty breathing or can no longer stand are significantly more likely to die from the disease, the study reported.

Comparing case studies of 30 horses and a donkey admitted to the university's clinic between 1991 and 2006, van Galen's team found that 84% of the animals were 5 or less than 5 years old and that 77% of these died or were euthanized within eight days of diagnosis, compared to 20% of those older than 5. The total survival rate of all equids in the study was 32%. Whereas the average age of survivors was 6.7 years old, that of the non-survivors was less than half that age, at 3.2 years. None of the equids had been properly vaccinated, according to the study, although some of them had received TAT preventively (before castration, for example).

"All horses are at risk for tetanus," van Galen said. "But sadly, more and more people truly believe that there is no good reason for vaccinating against tetanus besides putting money in veterinarian's pocket. Horse owners need to understand that it only takes a very small wound, often invisible to us, to develop tetanus. Also, they should never subject their horses to non-urgent surgical procedures--especially castrations--unless (the horse has) been vaccinated. You just can't rely on the TAT, but proper vaccination saves lives and money."

Proper vaccination, she said, means a TAT for newborn foals, a primary vaccination at 4-6 months of age, a booster 30-60 days later, and a yearly booster. Pregnant mares should be vaccinated three to five weeks before foaling, not only because retained placentas account for a source of tetanus but also because it ensures the passage of antibodies through the colostrum to the newborn foal. TAT should be administered to any horse not properly vaccinated when the known tetanus risk is high (when there are wounds, foot abscesses, emergency procedures, etc.). "But even with the TAT, start a proper vaccination regimen immediately," she said.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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