Also known as 'lock jaw', tetanus is a disease caused by the bacteria Clostridium tetani. Most people are aware of tetanus due to having received the vaccine for the disease.
The bacteria produce a neurotoxin (known as 'tetanospasmin toxin') which causes painful muscle contractions and spasms. The bacteria can be found in soil, manure and the intestinal tracts of many animals, where it does not produce disease. They are obligate anaerobes, (meaning they live in conditions where there is little to no oxygen), in warm-blooded animals. It affects many mammals including humans but is quite rare in cats as they appear to be resistant to the effects of the toxin.
The bacteria produces spores which are extremely hardy and resistant to heat and a multitude of disinfectants. These spores can survive for years in the environment and can be found in the feces and the skin of mammals. When spores are introduced to the body, if conditions are right, and there is no oxygen (for example, if the wound is deep or has closed over) the spores germinate into the vegetative form which produces its toxin.
How do cats become infected with tetanus?
The majority of cases involve a deep puncture wound which injects the bacteria under the skin. Rusty nails and cat fights are two common ways the bacteria can enter the body, however, any injury which penetrates the full thickness of the skin has the potential to introduce C. tetani into the body.
What are the symptoms of tetanus?
Symptoms of tetanus occur between 10-14 days and may include:
Most cats only develop localised symptoms around the area of the wound. Outstretched limbs which start out with spasms and later become completely rigid.
In some cases a day or so after localised stiffness occurs, generalised stiffness and rigidity will present in many of the major muscle groups as the nerves throughout the body become affected. Contractions may occur with anything that stimulates the cat (hyperesthesia), such as sound, light and even a light touch. The ears are erect, the jaw muscles are involuntarily locked, making eating, drinking and breathing difficult. Fixed contracture of the facial muscles may result in a 'grin' like appearance, known as risus sardonicus. The tail is stiff and the cat has difficulty blinking.
As the disease progresses, the entire body may become rigid causing the cat to lie on his side with his limbs outstretched.
Temperature is often mildly elevated due to increased muscle activity.
Seizures may occur in advanced cases of tetanus.
How is tetanus diagnosed?
There is no test for tetanus, your veterinarian will perform a complete physical examination of your cat and obtain a medical history from you.
Diagnosis is generally made from presenting symptoms such as limb stiffness and rigidity in the muscles. A wound close to the area of muscle spasms/rigidity will raise your veterinarian's index of suspicion, however, in some cases, the wound may have healed over before symptoms of tetanus become apparent.
In some cases, your veterinarian may choose to check for C. tetani antibodies in the blood serum.
How is tetanus treated?
Treatment involves killing the bacteria and offering supportive care, which is very labour intensive:
Antibiotics (usually penicillin or metronidazole).
Cleaning and debriding the wound.
Tetanus antitoxin is a product which is administered via intravenous injection which neutralises the toxin. This only works on the toxin which hasn't yet bound to the nerves. There is a risk of anaphylaxis with this as it is made from the blood of another animal (horse).
Sedatives will be prescribed to control spasms, seizures and to help manage over-stimulation.
Muscle relaxants may be prescribed to help relieve muscle rigidity.
Tube feeding may be necessary for some cats.
Soft bedding and regular turning to avoid bed sores developing.
Your cat will need to be placed in a quiet, dark room to avoid over-stimulation.
It can take many weeks for your cat to recover from tetanus.
Is there a tetanus vaccination for cats?
No, while there is one for humans (and horses), there is no vaccination available for cats or dogs.
The prognosis is variable. Cats with localised disease have a better outcome than those with generalised disease.