Tetanus is characterized by the onset of tonic muscle spasms and reflex hyperexcitability. It is caused by toxins produced by the bacterium Clostridium tetani, which affects both humans and domestic animals, with horses being particularly susceptible to infection.

The infection is usually transmitted through contamination of accidental wounds or surgical sites and can also occur via soil or manure. Horses with puncture wounds require extra care, as these wounds are more prone to contamination and bacterial growth due to the anaerobic conditions they create. In foals, infection can occur through the umbilical cord, where the spores germinate and the bacillus multiplies, releasing the following toxins:

  • Tetanospasmin: responsible for triggering neurological symptoms, spreading throughout the body and central nervous system via the bloodstream and axonal migration.
  • Tetanolysin: a hemolysin that promotes infection progression, enlarges necrotic areas, and creates ideal anaerobic conditions for bacterial proliferation.

The disease has an incubation period of 7 to 14 days, sometimes extending up to a month. The closer the wound is to the horse’s central nervous system, the more aggressive the incubation period and clinical signs tend to be.

Horses affected by tetanus exhibit clinical signs such as weak chewing, slow and difficult swallowing, muscle stiffness that makes movement hesitant, which in severe cases can result in total immobility. Additional signs may include: protrusion of the third eyelid, frequent facial muscle contractions, nictitating membrane protrusion, ears positioned in a scissor-like manner, legs stiff and spread like a sawhorse, dilated nostrils, generalized spasms, profuse sweating, and labored breathing.

In aggressive cases, death may occur within 5 to 15 days after the first symptoms appear. In slower-progressing cases, this period can extend to 20 days.

Early detection and prompt treatment greatly increase the horse’s chances of survival. However, treatment is complex. In cases of dehydration, intravenous administration of Ringer’s solution is used to maintain the body’s fluid and electrolyte balance. For metabolic acidosis, sodium bicarbonate (5–10%) may be administered. Muscle relaxants, such as benzodiazepines, are given to reduce hyperreflexia. Antibiotics, including procaine penicillin G combined with benzathine penicillin, help eliminate the infection and prevent toxin production. Additionally, antitoxins such as tetanus serum may be administered intramuscularly or subcutaneously. All treatments should be prescribed and monitored by a veterinarian, as individual horses respond differently.

While cure is possible, recovery is slow and can take over 15 days.

Prevention is crucial. Vaccinate your horse annually, administer tetanus antiserum after injuries, prevent open wounds from contacting soil or dirt, and always disinfect wounds promptly.

By taking proper care of your horse’s health, you ensure many more years alongside this loyal companion.