Tetanus, sometimes called "lockjaw", is caused by the bacterium Clostridium tetani which produces a neurotoxin that causes violent muscle spasms and contractions and hyperflexive responses.
The bacteria are normal residents of the soid, but they can contaminate dead or dying tissue in a penetrating wound. The spores germinate soon after entering the wound. Germination is followed by the production of the neurotoxin, tetanospasmin, which affects neuromuscular responses. The toxin blocks nerve impulses that normally inhibit muscular contractions which results in large muscle groups trapped in a state of contraction.
The clinical signs reflect sustained muscle contraction:
Most untreated dogs will die, usually as a result of respiratory insufficiency.
Thorough cleansing and disinfection of the wound to remove dead or dying tissue and clostridia spores is absolutely essential. Antibiotics in the wound area and systemically are used to kill any remaining bacteria. Tetanus antitoxin may also be administered to gather up unbound toxin. Supportive and nursing care will affect the recovery of the animal. Several days may pass before any improvement in the animal is seen and complete recovery may take weeks of therapy.