Tetanus is a disease of warm-blooded animals. The clinical signs associated with this disease are caused by tetanospasmin, a potent bacterial neurotoxin. Muscle stiffness and spasms are typical of the disease. Fortunately, tetanus is uncommon in dogs and cats, but it is seen occasionally by veterinarians. Tetanus is caused by Clostridium tetani, a bacterium that produces spores that persist in the environment, such as in dirt and debris. The spores are resistant to boiling and to many disinfectants. Spores of Clostridium tetani enter wounds, where they multiply and produce the neurotoxin that affects the transmission of information from nerves to muscles which leads to the severe muscle stiffness, a characteristic of this disease.
Signs usually develop 5-21 days after a wound is infected with the bacteria. General signs include facial muscle spasms which is called lockjaw. It also causes increased salivation, difficulty swallowing and extreme stiffness of the legs. It can also cause elevated body temperature and altered heart and respiratory rates because of the muscles of the heart and lungs being affected. Spasms of the muscles of the voice box, chest and diaphragm may make breathing difficult. Animals may appear to have increased sensitivity to sound and touch. Facial muscle spasms may cause wrinkling of the forehead and retraction of the lips, as if the animal is smiling or grimacing. This facial appearance is known as risus sardonicus. Extreme rigidity of the legs may give the animal a sawhorse stance or cause it to fall over and be unable to walk. The legs are often held straight and are difficult to bend.
Diagnosis is usually based on the clinical signs and a history of a bite wound or surgical procedure performed within the previous three weeks. Culture of the organism from an infected animal is very difficult and therefore usually not done.
Treatment involves cleaning all wounds thoroughly. Severely affected animal’s require intensive supportive care and prolonged hospitalization. Supportive treatment may include intravenous fluids, indwelling feeding tubes, an assisted ventilation with a mechanical ventilator. Sedatives and muscle relaxants may be needed.
Continuous supportive care is essential for successful recovery of animals with generalized tetanus. Because the disease is not that common in dogs and cats, vaccination is usually not recommended. Prognosis for recovery from tetanus is variable, depending on the severity of clinical signs at the time treatment is started. Recovery from generalized tetanus can take weeks to months.
Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.