Tetanus Easier to Prevent Than Treat
By: Dr. Harold Newcomb, D.V.M., technical services veterinarian, Merck Animal Health
The age-old saying that “an ounce of prevention is worth a pound of cure” is true for many animal health protocols, especially with some diseases being more difficult to treat than others. Tetanus is one such disease. Treatment is not dependably successful – fatality rates can approach 50 percent. While tetanus vaccination isn’t always part of a herd health protocol, it deserves attention especially during wet spring weather when it is often more prevalent.
Clostridium tetani, the bacterium that causes tetanus, can survive in the environment for years. If an open wound is contaminated with soil or manure, the spores of C. tetani can enter the wound and grow rapidly, producing tetanus neurotoxin. The toxin binds irreversibly to the animal’s nerve endings and travels back to the spinal cord, causing spastic paralysis.
The signs of tetanus are subtle and often missed until it’s too late for an animal to have a good chance for a successful recovery. Therefore it’s important to identify those most at risk of falling victim to this often deadly disease.
It starts in the soil
Technically, any animal with an open wound or has tissue with little or no exposure to oxygen is vulnerable, but two instances when cattle are at a heightened risk of tetanus are at calving and when bull calves are castrated. The most common infection sites are deep wounds, infected areas of the vulva or vagina following a difficult birth and severe uterus infections.
Watch for cows that lay in the soil to give birth, as an oxygen-deprived uterus, if exposed to the soil, can result in tetanus and illness due to infection. But at a higher risk for tetanus are older calves castrated with the elastrator or banding method.
Younger calves are at lower tetanus risk because their testicles are smaller and the scrotal sac falls off more quickly than heavier calves. The clostridium organisms do not have enough time to grow. This is one of the reasons why the American Veterinary Medical Association recommends that calves should be castrated before 90 days of age.
Because banding shuts off the blood supply to the testicles and causes the scrotum to fall off, banded calves are at risk of infections and tetanus. This is especially true if more tissue than needed is entrapped in the band.
Open castration, if not done properly, is also risky. When the scrotum is cut for castration, it is important not to allow it to pull back and seal up – it needs to drain. Either use a Newberry castrating knife or cut the scrotal sack at a 45-degree angle, which allows for drainage.
If possible, allow calves to go back on pasture after castration. Calves going into a dry lot are more likely to have tetanus be-cause there is more dust and dirt in that environment.
Once you encounter tetanus in your operation, you will likely have to practice regular prevention. The good news is if you vaccinate properly, tetanus will not usually be an issue.
Talk with your veterinarian to develop a management protocol. He or she may recommend a vaccination program that includes a vaccine, such as Covexin 8® or Calvary 9,® that contains a tetanus toxoid. Protective antibody levels should develop in two weeks following the booster injection. It is important that two doses are given, with the last dose two weeks before castration to achieve solid protection.
Cleanliness is another important management practice, especially during castration. Keep instruments clean in a bucket with water and disinfectant, such as betadine or iodine solution. Always wash your hands in the disinfectant before beginning and between calves. Avoid touching the chute or the calf’s body. If the scrotum is dirty, wash it with disinfectant. Replace water and disinfectant regularly so it remains effective.
It is also important to practice clean-liness during calving. If a cow has dystocia, make sure all instruments are clean and that you are clean when working with her. Administering an antibiotic also is a good practice to temper infection until the cow can build up more immunity. Using an antibiotic with efficacy against tetanus is important as some don’t work on tetanus. Work with your veterinarian on this issue.
Involve your veterinarian
The key is to work with your veterinarian to design a total herd health program that takes your cows’ environment and tetanus risk into consideration.
The same is true for calves. Castration is a necessary management practice. Your veterinarian can establish protocols, such as early castration, that can reduce the risk of tetanus.
Ask your veterinarian if your protocols need to be modified, as this professional knows your operation and your needs.