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First Posted: Aug 28, 2010
Aug 19, 2012

Tetanus or Lockjaw in Horses

by Debora Johnson

Diagnosing and Managing Tetanus and Botulism in Horses (An excellent article)

Tetanus is a dreadful disease. All warm blooded mammals are able to get tetanus AKA lockjaw. This malady is found all over the globe. Clostridium tetanian is found in the soil and in the intestinal tracts of man and animals. When oxygen is not present this organism grows and thrives. It protects itself by a protective capsule and lives in the soil for log periods of time when oxygen is present. When horses are exposed to this organism in a wound clostridium tetanian grows and thrives producing toxins that affect the nervous system. Ten to fourteen days is the incubation period after the wound has been contaminated.


Clostridium tetani with characteristic 'tennis racket' appearance.

Toxin Action

"Tetanospasmin is distributed in the blood and lymphatic system of the host. The toxin acts at several sites within the central nervous system, including peripheral nerve terminals, the spinal cord, and brain, and within the sympathetic nervous system. The toxin is taken up into the nerve axon and transported across synaptic junctions, until it reaches the central nervous system, where it is rapidly fixed to gangliosides at the presynaptic junctions of inhibitory motor nerve endings.

The clinical manifestations of tetanus are caused when tetanus toxin blocks inhibitory impulses, by interfering with the release of neurotransmitters, including glycine and gamma-aminobutyric acid. This leads to unopposed muscle contraction and spasm. Characteristic features are risus sardonicus (a rigid smile), trismus (commonly known as 'lock-jaw'), and opisthotonus (rigid, arched back). Seizures may occur, and the autonomic nervous system may also be affected. Tetanospasmin appears to prevent the release of neurotransmitters by selectively cleaving a component of synaptic vesicles called synaptobrevin II." Clostridium tetanian

Symptoms in Horses

  • Muscle Stiffness (jaw, neck and hind end)
  • Over all stiffness
  • Difficulty eating
  • Spasms
  • Colic
  • Diarrhea
  • Sweating
  • Circulation and respiration are affected
  • Increased heart rate, rapid breathing, and congestion of mucous membranes
  • Hypersensitivity
  • Eyelid involvement
  • Erect ears
  • Stiff tail
  • Dilated nostrils
  • Movement difficult
  • High temperatures up to 110 degrees
Prevention of Tetanus in Horses
  • Vaccinate your horse yearly
  • For puncture wounds
    1. Clean well.
    2. Disinfect
    3. Drainage is necessary
    4. Have vet out no matter what
    5. Follow vets instructions to the letter
  • Another tetanus shot may be necessary depending upon when the last one was given.
  • 80% mortality without preventative measures.
  • For More Information:

    Merck Vet Manual

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