Tetanus (Clostridium tetani infection) is a potentially life-threatening neurologic disease affecting all species of domestic livestock, including cattle. The clinical signs of tetanus are subtle and often missed until the disease is advanced. At that point, treatment and management of the affected animal is very difficult and the chance for recovery is poor. Recognition of the initial signs of stiff legs, an anxious expression with ears held back toward the poll, moderate bloat, erect tail, and the unusual “flick” of the third eyelid across the eye leads to an accurate early diagnosis and allows treatment to begin when it is most effective. Any calf castrated with an elastrator band should be given tetanus prevention in the form of either tetanus toxoid (two doses required with the 2nd given two weeks prior to castration), or tetanus antitoxin (given the day of banding).
The most common infection sites in cattle for C. tetani include deep wounds with dead tissue, infected areas of the vulva or vagina following difficult birth, and severe infections in the uterus. Management practices that may create environments perfect for germination of C. tetani spores include dehorning, elastrator band castration, nose ring placement, tail docking, and ear tag placement. The incubation period averages seven to ten days but can be much longer.
Basic principles for medical management of tetanus cases in cattle are to provide muscle relaxation, neutralize the circulating unbound TeNT toxin, begin establishment of active immunity, eliminate the C. tetani infection with antibiotics, maintain hydration and nutritional status, and provide good footing with deep bedding. Tetanus antitoxin may catch and inactivate any circulating toxin but cannot undo the effects of toxin already bound to nerve receptors. To initiate active antitoxic immunity, a dose of tetanus toxoid should also be delivered in the muscle. Once the wound or infection site is identified, then it must be thoroughly cleaned to remove all dead tissue and should be flushed with hydrogen peroxide to reduce toxin production by any remaining actively growing bacteria. Antibiotics, primarily penicillin, are recommended at high doses in the muscle for at least 7 days. The animal’s hydration status should be monitored closely and intravenous fluids may be needed if unable to drink. If the patient develops free gas bloat requiring stomach tubing, then a rumen trocar should be placed to relieve gas buildup until the patient regains the ability to eructate. The opening provided by the trocar can also provide a portal for the delivery of water and feed to the rumen.
The mortality or death rate may reach 50% in cattle, but animals that survive longer than seven days have a fair-to-good chance of complete recovery. Mild cases usually respond to treatment within one week, but it is important to realize that many patients may improve then develop unforeseen complications that result in death or the need for euthanasia. Regaining the ability to drink is one of the most encouraging signs of recovery. Cattle that end up down on their side with straight, stiff legs usually require euthanasia.
Prevention involves reducing the risk of cattle developing deep wounds or areas of dead, rotten tissue where C. tetani spores may germinate along with the use of vaccines in animals at risk for infection. It is important for veterinarians and producers to maintain clean conditions and disinfected instruments for all procedures. Cattle are not routinely vaccinated against tetanus, and most 7- or 8-way Clostridial (blackleg) vaccines do not contain specific protection against C. tetani although some do (for example, Covexin 8® and Calvary 9®-Merck) contain a tetanus toxoid. Cattle can be vaccinated easily and inexpensively with tetanus toxoid and protective antibody levels should develop in two weeks following the booster injection (2nd shot) of the series. Tetanus antitoxin is recommended for immediate, emergency treatment of exposed or at risk animals when clinical tetanus is suspected or could develop but protection only lasts 10-14 days.
Michelle Arnold, DVM, University Of Kentucky Extension