Tetanus – ‘lockjaw’

Horses are susceptible to a number of serious infectious diseases, e.g. tetanus (lockjaw) and influenza (flu), fortunately there are vaccines available for some of these common conditions.

Tetanus can be a fatal disease, caused by the neurotoxin of Clostridium tetani, which is found in soil and enters the horse’s bloodstream, usually via an open wound. Even small wounds, including foot punctures, can allow Clostridium tetani contamination and, because the incubation period is 7-21 days, the wound has usually healed by the time the first signs of the disease are apparent.
Often owners are not even aware that their horse has received a wound or thought it minor and of no importance and yet their horse develops tetanus. The disease can be prevented by immunisation with tetanus toxoid or the use of antitoxin which is routinely carried out in horses.

Signs, which are exaggerated with stimuli, include:

  • Vague stiffness in the head and limbs
  • Rigid posture, sometimes called ‘sawhorse stance’
  • Spasms in the muscles of the head and neck resulting in difficulty chewing, nostril flaring, erect stiff ears and wide-eyed expression
  • Difficulty in opening the mouth, sometimes called ‘lockjaw’
  • Trembling progressing to violent, whole body spasms in response to sudden movements or noise
  • Extension or elevation of the tail
  • Protrusion of the third eyelid
  • Recumbency, muscular spasm and paralysis of respiratory muscles leading to death.

Vaccination is essential and very effective. Most horses that are vaccinated against equine influenza (flu)will be protected against tetanus, as vaccinations tend to be combined. If this is not the case and your horse is vaccinated with a separate vaccine, the schedule for tetanus vaccination is:

  • Primary course – 2 injections, 28-42 days apart
  • First booster – within 365 days of 2nd injection
  • Following boosters – only needed every 1-2 years

Pregnant mares should be given a tetanus booster in the last 4-6 weeks of pregnancy which will provide the foal with some protection through the milk for the first 6-12 weeks of life.
Foals can also be given an injection of tetanus antitoxin (an ‘antidote’ to the infection) as soon as possible after birth to provide temporary cover for 3-4 weeks. This should be followed by another dose after 4 weeks. Regular tetanus vaccination can be started at 3 months old.

If you observe any signs of tetanus then make sure you do the following:

  • Call the vet immediately
  • Keep your horse in a quiet, cool, dark stable away from any hustle and bustle
  • Minimise any external stimulation, i.e. noise. Plug your horse’s ears with cotton wool
  • Provide your horse with soft food and water at muzzle level
  • Your horse may need to be put in a sling if there is danger of falling.

Tetanus is a highly fatal disease and the prognosis for your horse is poor, unless diagnosed and treated aggressively early on. Mild cases can recover with careful nursing and treatment. Some horses will survive, but will show signs of having suffered from the disease, e.g. skin de-pigmentation subsequent to decubital ulcers. Any signs of the disease should begin to disappear within two weeks if your horse is to recover.