Tetanus

What is tetanus?

Tetanus is a potentially fatal disease characterized by muscular spasms caused by a neurotoxin produced by the bacterium Clostridium tetani. These organisms, and their spores, are found in the intestinal tract of horses and other species and are abundant in the soil, where they can survive for many years. The spores can enter open wounds, particularly puncture wounds, where they proliferate under the right conditions. When the spores die, they release the tetanospasmin neurotoxin that is responsible for clinical signs. The size of the wound does not correlate to risk of developing tetanus. Even superficial wounds have been associated with clinical cases.

What are the clinical signs of tetanus?

Clinical signs of tetanus usually include history of a wound (typically within the preceding month) and stiffness, lameness, or colic. These signs generally progress quickly to an abnormal gait, trembling, and muscle spasm. An inability to open the mouth, known as “lockjaw”, may occur. Horses can exhibit profuse sweating, saliva accumulation in the mouth, and may aspirate feed material. Excitement, including loud sounds or bright light, often exacerbates clinical signs. Horses may become very sensitive to touch. Stiffness in the leg muscles may result in a characteristic “sawhorse” stance. Affected horses can progress to severe muscle rigidity, making it difficult to rise, urinate, or defecate. Respiratory failure can occur.

How is tetanus diagnosed?

A diagnosis of tetanus is usually made based on clinical signs and recent wound history. In some cases, C. tetani may be cultured from the wound.

How is tetanus treated?

Tetanus may be treated with antibiotics, usually penicillin, injection of tetanus antitoxin, and other medications. Horses are kept in dark, quiet stalls with deep bedding. Stalls with padded walls may be used to further minimize injury. Slinging may be required in severe cases.

What is the prognosis for tetanus?

The prognosis is grave for horses that are recumbent, especially if clinical signs progressed rapidly. Affected horses that are able to stand have a fair prognosis, with improvement occurring within 2-6 weeks. Full recovery is possible. The mortality rate for tetanus in horses is reported to be up to 80%.

How can tetanus be prevented?

Fortunately, tetanus is easily preventable. The tetanus toxoid is a core vaccine recommended by the American Association of Equine Practitioners (AAEP) for all horses, and boosters should be administered annually. Horses that sustain a wound more than six months after vaccination should be revaccinated immediately.

In addition to vaccination, proper first aid and wound care can help prevent tetanus. Keep stalls, paddocks, and other barn areas free of materials that could cause injury.

For more information

Tetanus vaccine guidelines, American Association of Equine Practitioners: https://aaep.org/guidelines/vaccination-guidelines/core-vaccination-guidelines/tetanus