Merck Manual

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Tetanus in Dogs


Henry R. Stämpfli

, DVM, DrMedVet, DACVIM, Large Animal Medicine, Department of Clinical Studies, Ontario Veterinary College, University of Guelph

Last full review/revision Jun 2018 | Content last modified Jun 2018
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Tetanus toxemia is caused by a specific poison, or toxin, that blocks inhibitory nerve signals, leading to severe muscle contractions and exaggerated muscle responses to stimuli. The toxin is produced by Clostridium tetani bacteria in dead tissue. Almost all mammals are susceptible to this disease, although dogs are relatively resistant.

Clostridium tetani is found in soil and intestinal tracts. In most cases, it is introduced into the body through wounds, particularly deep puncture wounds. Sometimes, the point of entry cannot be found because the wound itself may be minor or healed. The bacteria remain in the dead tissue at the original site of infection and multiply. As bacterial cells die and disintegrate, the potent nerve toxin is released. The toxin causes convulsions of the voluntary muscles.

Dogs with tetanus may stand with stiff legs.

Dogs with tetanus may stand with stiff legs.

The incubation period varies from 1 to several weeks but usually averages 10 to 14 days. Localized stiffness, often involving the jaw muscles and muscles of the neck, the hind limbs, and the region of the infected wound, is seen first. General stiffness becomes pronounced about 1 day later, and then spasms and painful sensitivity to touch become evident. Spasms are often triggered by sudden movement or noise. Because of their high resistance to tetanus toxin, dogs often have a long incubation period and frequently develop tetanus that is localized to the area of the wound, such as stiffness and rigidity in the limb with a wound. The stiffness can spread to the opposite leg then progress toward the head. When generalized tetanus does develop, the ears are erect, the tail is stiff and extended, and the mouth is partially open with the lips drawn back.

Tetanus is diagnosed based on an animal's history of having a wound and the presence of the signs. Laboratory tests may sometimes also be necessary. In the early stages of the disease, your veterinarian may recommend muscle relaxants, tranquilizers, or sedatives along with tetanus antitoxin. This treatment is supported by draining and cleaning the wounds and administering antibiotics.

Good nursing is invaluable during the early period of spasms. If your pet has tetanus and will be returning home with you rather than staying in a clinic, be sure to follow the nursing care instructions fully and carefully.

Also see professional content regarding tetanus.

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