Infectious Diseases

Thoroughbred Filly Beats the Odds to Survive Tetanus

By Rob Warren

Tenacious Candy, a 2-year-old Thoroughbred filly, lived up to her name when she endured an extended hospitalization to survive tetanus. Days after experiencing a cut on her leg, she went down in an exerciser. It took 3 men and a tractor to get her up. Initially, she could eat and drink, but over a period of hours, she stiffened.

Nearly unable to stand, Tenacious Candy was taken to the Large Animal Clinic at the UC Davis veterinary hospital where specialists in the Equine Internal Medicine Service observed a horse with a prolapsed third eyelid, a rigid mouth and a stiff body and tail—classic signs of tetanus.

Tetanus is a potentially fatal disease characterized by muscular spasms caused by a neurotoxin produced by the bacterium Clostridium tetani. The organisms are abundant in the soil and surrounding environments, where they can survive for years. Once the spores enter open wounds, they release toxins that quickly affect the host and produce clinical signs by preventing muscles from relaxing normally.

Horses are especially sensitive to the bacterium—the prognosis for unvaccinated horses is often poor if the disease progresses, and the animal becomes unable to stand or breathe. Standing horses have a better chance, but the prognosis is still only fair. However, recovery is possible with adequate treatment and supportive care.

Tenacious Candy was given tetanus anti-toxin medication and supportive care of fluid therapy, muscle relaxants and a quiet environment of low light, low noise and low activity, as horses with tetanus are overly sensitive to stimuli. She did well during her week of hospitalization, with improvement in her ability to eat and reduction in stiffness and was transferred to the veterinary school’s Center for Equine Health for rehabilitation.

“It is not a recovery that can happen overnight,” said Emily Berryhill, DVM, DACVIM, an assistant professor of equine medicine. “Horses recovering from tetanus routinely go through an extensive rehabilitation process. The toxins can be out of their system after being bound with antitoxin, but the damaged neuromuscular junctions need several weeks to regenerate.”

Unfortunately, Tenacious Candy sustained significant muscle weakness as part of the disease process and tore a muscle in her hind leg while attempting to stand during rehabilitation. She was taken back to the hospital and placed in a sling to stabilize her and prevent further injury. After nearly a month, she was discharged after being able to lay down and get up repeatedly on her own.

“It is not easy for a young, high-energy horse to stay in a stall for that length of time, let alone tolerate a sling. We all grew to love her personality and spark, which helped her survive the worst. She truly lived up her name.” Dr. Berryhill said.

Tetanus is preventable with vaccination. Foals should have a primary vaccination series of 2 doses at a 4- to 6-week interval, followed by repeat vaccinations at 1 year of age and then annually thereafter. Even though Candy was vaccinated on schedule, it is possible that she did not generate the full immunity needed as a foal, increasing her risk for developing tetanus. However, her previous vaccinations did provide partial immunity, which probably helped her survive. Mortality rates of unvaccinated horses exceeds 75%, according to the AAEP.

“In addition to vaccination, proper first aid and wound care can help prevent tetanus,” she said. “We recommend keeping stalls paddocks and other barn areas free of materials that could cause injury and seeking veterinary intervention for wounds, even if small.” MeV

This story originally appeared on the UC Davis website. It was edited for space and style.
https://www.vetmed.ucdavis.edu/news/equine-medicine-specialists-help-thoroughbred-filly-beat-odds-survive-tetanus