Tetanus is a disease caused by the effect
of a nervous system poison (neurotropic toxin) on the central
nervous system. The nervous system poison is produced by the
bacterium, Clostridium tetani. The bacterium is found in soil
and as part of the normal bacteria of the intestinal tract
of mammals. The tetanus bacterium lives and grows without
oxygen (that is, it is an anaerobic bacterium). It produces
a potent toxin or poison (tetanus toxin). Tetanus is found
worldwide, especially in the tropics. Tetanus occurs occasionally
in dogs. It is rare in cats.
What causes Tetanus?
Tetanus is caused by a nervous system
poison (tetanus toxin) released by Clostridium tetani. The
bacteria invade the body through a skin wound. Tetanus historically
is associated with puncture wounds because the small, narrow
entrance blocks oxygen and makes the environment more desirable
for Clostridium. The tetanus bacteria prefer contaminated
wounds, especially those containing dead tissue. Surgical
wounds, lacerations, burns, frostbite, open fractures, or
abrasions can become infected with Clostridium tetani. Untreated
wounds provide easy access for infection. Outdoor pets are
more at risk for developing tetanus than are indoor pets.
Vaccinating dogs and cats with tetanus toxoid can prevent
tetanus. Good management to prevent skin wounds by providing
clean, safe environments decreases the likelihood of injury
and resultant tetanus. Early and thorough wound cleaning,
especially in tetanus-prone wounds, can prevent infection.
Any deep, contaminated wound should be treated with antibiotics.
What are the signs of Tetanus?
Signs of tetanus appear a few days to
a few months after the bacteria enter a wound. The wound may
be healed by the time the signs of tetanus appear. Localized
signs are mild rigidity of muscles near the wound. The animal
will be stiff with a stilted gait. Mild weakness or incoordination
may be present. The signs may disappear, reflecting an immune
response to the tetanus toxin, or the disease may worsen and
become generalized. If this occurs, the animal's tail will
stretch out and there will be progressive tightening of the
muscles to the point of a "sawhorse" appearance. Painful convulsions
occur and the animal may have difficulty breathing. The eyelids
retract and the forehead becomes wrinkled. The ears become
erect and the animal has a grinning appearance. The animal
will have difficulty opening its jaw (lockjaw). Fever, painful
urination, and constipation can occur. Sudden movement, noise,
or touch can stimulate muscle spasms. Death occurs during
spasm of the throat and breathing muscles because of a lack
How is Tetanus diagnosed?
Tetanus is diagnosed by history, physical
examination, and laboratory analysis. Lead and strychnine
poisoning can mimic tetanus and must be considered as possible
causes of the clinical signs. Complete blood counts (CBCs)
and blood chemistries may indicate abnormalities as a result
of muscle damage during the later stages of the disease. The
blood serum may be analysed for the anti-tetanus antibody,
but it is often undetectable. The wound is cultured but is
usually unsuccessful in yielding Clostridium tetani. A spinal
tap may be done to obtain cerebrospinal fluid for analysis
of other bacteria that may cause similar signs.
How is Tetanus treated?
Good supportive care and constant nursing
care are important in the treatment of tetanus. The animal
is hospitalised for a prolonged period of 3 to 4 weeks. The
airway and breathing is maintained and it may be necessary
to insert a breathing tube (endotracheal tube). Tracheostomy
(emergency surgical incision into the windpipe [trachea] to
create an airway) may be needed. The pet is kept in a darkened,
quiet area on soft bedding and should not be disturbed. Wounds
are cleaned and dead tissue is removed surgically. Wounds
may be irrigated with salt solutions. They should be kept
open to the air and drained of any secretions. A feeding tube
is inserted and the animal is fed gruel and water through
the tube. Fluids are administered intravenously (through a
vein) to help remove toxic products that occur because of
muscle spasms. Medications are administered to sedate and
calm the animal. Tetanus antitoxin is given. Penicillin is
administered but antibiotics have no effect in later stages
of the disease. The vital signs (blood pressure, heart rate,
breathing rate) are monitored closely and the animal moved
cautiously to prevent skin breakdown or ulceration.
What is the prognosis for animals with Tetanus?
The prognosis (outcome) for animals with
tetanus is guarded. Prognosis depends on a number of factors.
The amount of tetanus toxin bound to the nerves influences
the prognosis; the more toxin bound to the nerves, the poorer
the prognosis. The prognosis improves with surgical removal
of damaged tissue and medical treatment. However, the course
of recovery is slow and requires physical rehabilitation for
the animal to regain full use of its limbs. Untreated tetanus
usually is fatal.
Vaccination against tetanus is routinely advised for horses
and people, but is not advised for cats and dogs.
A PET WITH TETANUS
I have a dog, a three-year-old American Staffordshire, who
got a tetanus infection two weeks ago. Tetanus is not common
here in Oslo where I live - it has been 10 years since a dog
got infected in Norway. My dog has recovered a bit, but no
one can tell me how long it will take for her to get better,
and if there is anything other than good care and rest that
can help the recovery process.
Tetanus is very rare in the United States as well. Dogs and
cats tend to have a natural resistance whereas horses and
humans are the most susceptible to the illness. Tetanus is
caused by an anaerobic (living in environments free of oxygen)
bacteria, Clostridium tetani, that is spread by a penetrating
wound or by contamination of an already existing wound. It
is killed by digestive enzymes, and therefore does not cause
illness when ingested. Clostridium tetani produces two toxins,
one of which, tetanospasmin, causes a blockage of neuromuscular
transmission--that is, paralysis. The blockage is irreversible
and recovery relies on the creation of new nerve cells.
Signs of the illness can take up to three weeks to develop
after exposure has occurred. Paralysis can be localized, affecting
only one limb (the one nearest the offending wound), or generalized,
affecting all four legs. Death can follow due to respiratory
arrest, and only occurs in those cases that go undiagnosed.
Recommended treatments include:
Made from equine or human serum, this serves to bind any
toxin still circulating in the bloodstream looking to
do damage. It doesn't undo damage, but it prevents more
from occurring. It can be given intramuscularly or intravenously.
The intravenous route is faster and more effective, but
carries risk of anaphylaxis (severe allergic reaction),
so care must be given when using this method.
These are given locally and systemically to remove any
bacteria that are still living in the animal and actively
producing toxin. Penicillin G is the antibiotic of choice
and is given intravenously as well as in the muscle near
the wound. Other antibiotics that work well include metronidazole
Phenothiazines (tranquilizing agents), such as chlorpromazine,
are given to stop the hyperexcitable behavior together
with barbiturates, such as pentobarbital or phenobarbital,
to control the convulsions. Attention must be paid to
the heart rate when using these drugs. If it falls below
60 beats per minute, another drug will be needed to speed
up the heart. Sedatives need to be given every three hours.
This may be necessary to limit the size of the wound and
is generally done under general anesthesia to eliminate
as much bacteria as possible. Hydrogen peroxide is a good
cleansing agent for removing anaerobic bacteria and should
be used often to flush the wound.
DRUGS: Both an increased and a decreased heart rate
can result from tetanus. Usually the increased rate is
corrected by the above mentioned sedatives. The decreased
heart rate should be treated with atropine or glycoyrrolate
CARE: While in the recovery stage, your pet should
be kept in a dark, quiet area with as little excitement
as possible. She will be bedridden for a while, and will
need a very soft bed so she doesn't get sores from laying
on a hard surface for a long period. Your pet may have
muscular spasms of the jaw--commonly called lockjaw--so
it's a good idea to make her food into a gruel and feed
her small amounts slowly. The muscles used for swallowing
may also have spasms, so go slowly to avoid choking. If
your pet does not have regular elimination, both urine
and feces, touch base with your veterinarian to see if
a catheter is necessary.
A full recovery
is likely for both dogs and cats, and should only take about
three to four weeks. Good luck!
This article was on an email list I
belong to and unfortunately I can't credit the writer as I
don't know who wrote ( the person who posted it had not written