(Clostridum tetani)

What is Tetanus? 

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 of oxygen. 

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.


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: 

  • AN ANTITOXIN: 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. 

  • ANTIBIOTICS: 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 and tetracycline. 

  • SEDATIVES: 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. 

  • SURGERY: 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. 

  • CARDIAC 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 as needed.

  • NURSING 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 it).

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