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these anaerobic conditions are met and it is transported in the
blood to the central nervous system where it creates problems that can
eventually lead to paralysis and death.
Anywhere from several days to a month or more can be the incubation
period for tetanus and it all depends on the wound environment and the
proximity of the wound to the central nervous system. It is frequently
difficult for owners to pinpoint the injury or wound that initially
started the condition due to the long incubation period. Tetanus is common
in horses of all age but especially with those who have no vaccination
history.
The owner may first notice some increased muscle stiffness which is then
followed by muscle tremors. When the horse is walking or trotting this
stiffness will be noticed or the tail may be held out stiffly. Soon
restricted jaw movement will follow which is where the term lockjaw comes
from and there may also be a protrusion of the third eyelid.
The horse will appear anxious after the classic tetanus signs, during this
time the ears will be pricked forward and the nostrils flared. Chewing
will become more difficult as the disease progresses and drooling will be
evident. The horse will assume a saw-horse posture when walking becomes
extremely difficult and there will be a progressive stiffness of the limbs
and neck. Some horses may even fall and then have their legs remain rigid
and extended.
Asphyxiation is the most common cause of death in the horse which occurs
from the paralysis of the respiratory muscles. Five to ten days is the
typical course of the disease from the onset of clinical signs although
signs may persist for weeks in horses who appear only mildly affected.
There is always a guarded prognosis for horses with tetanus and the
prognosis is grave if the condition is left untreated. Supportive care for
these horses is usually very labor intensive and required a veterinary
referral center. Most of the veterinary work is aimed specifically at
eliminating the toxin from the horse through aggressive wound treatment,
neutralizing the existing toxin with an antitoxin and controlling muscle
spasms.
The key to tetanus control is prevention. The most effective and
inexpensive equine vaccine available is the tetanus vaccine and owners are
always encouraged to vaccinate all their horses. For mares they should get
a tetanus toxoid booster at least a month prior to foaling in order for
them to have good quality colostrum to pass on to the newborn foal. At two
months, the foal should be vaccinated and then again at three months and
six months of age. To maintain active immunity annual tetanus toxoid
boosters are sufficient.
Proper Care of Puncture Wounds
A mild dishwashing soap should be used to wash puncture wounds to remove
the dirt and congealed blood. You can use an antiseptic solution but it
should be used carefully since they can cause additional tissue damage if
the concentration is too high. Gently explore puncture wounds to check the
extent of the injury. X-rays may be necessary. Never suture puncture
wounds and in some cases they may need to be enlarged in order to be let
open to the air. The foot is the most common site for puncture wounds on
horses. A hoof knife can be used to open them and they should be kept open
in order to allow drainage and healing. Especially in the hoof many small
puncture wounds will go unnoticed which means it is imperative to have a
tetanus vaccination. Call your veterinarian right away if a puncture wound
enters a joint.
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