Tetanus is a widespread problem, seriously adversely affects animal health and is considered to be a feared disease. It has the ability to affect most animals including horse, cats, dogs, sheep and cows. These animals can be affected at age stage in their life, no matter what their age. Death is almost certainly always the result from an infection from this well-known, deadly disease.
Bovine tetanus is a highly infectious disease and is caused by a bacterium known as Clostridium tetani. It is the toxin tetanospasmin produced from the bacteria which lead to the adverse neurological effects of the disease. The bacteria replicate in the point of entry and then the toxins are transported to the central nervous system.
The disease is almost always fatal and transmission generally occurs following bacterial exposure to the bloodstream. This can include contact between the bacteria and an open wound. The pathogen is able to survive not only in anaerobic conditions but also away from its host for a long period of time. The bacteria can be found in the soil and these open wounds can be as a result of operations including castration and calving. As a result, animals that have undergone surgery are most susceptible to infection of bovine tetanus.
Symptoms include muscle stiffness, an excitable nature and “lock jaw”. These symptoms can be likened to equine tetanus in horses. The disease is said to be zoonotic which means it can be transferred to humans. Vaccinations are available to protect cattle herds against infection of bovine tetanus.
Transmission of bovine tetanus
Transmission commonly occurs when an unaffected animal has become exposed due to an injury resulting in an open wound. The cow is then susceptible to infection as the bacteria residing in contaminated soil are in effect given an entry point leading to the bloodstream. Cows are usually infected when wounded by contaminated nails or barbed wire. In some case, cows that have undergone surgery such as castration or calving become infected by bovine tetanus. Such nails and barbed wire are likely to have rusted.
The bacteria can survive in anaerobic conditions in the soil for very long periods of time. They are so resilient that they are unaffected by most disinfectants or high temperatures. This means that the disease is especially prevalent and difficult to eradicate, thus contributing to the spread of the bovine tetanus bacteria.
Symptoms of bovine tetanus
Initially, the cow will experience and show signs of increased sensitive to noise and light. The cow will react in a more excited manner and seem more irritable. Often, these signs are not noticed and farmers remain unaware of infection by the bacteria causing tetanus. The stress caused by this for the cow may aid in the development of infection. A high temperature may also be presented.
The progression of the symptoms provides an indication as to when the toxins are being produced. The cow will become stiff and will show a disinclination to move. The muscles may begin to tremor and signs of stiffness in the limbs, neck and tail will be observed. As a result the cow will seem uncoordinated and raise its tail. The cow’s jaw may stay in a state of permanent contraction and this is known as “lock jaw” and the cow will be unable to eat effectively. Additionally, the rumen may halt and this can lead to bloat.
In the later stages, the muscles will further contract and spasm. Protrusion of the third eye occurs mostly when the head is raised and often leads to a positive diagnosis. The disease becomes fatal when the cow collapses, convulses in addition to having very stiff legs.
Respiratory failure can also lead to death but often the cow is destroyed humanely before this can occur.
Treatment for bovine tetanus
Cattle diagnosed with bovine tetanus are treated using the tetanus antitoxin at the late stages of infection. Before this, however, antibiotics such as penicillin can treat the infected animal. Stress should be reduced and so sedation is sometimes required as well as placing the animal in a darkened area with little noise. If the infection has been diagnosed to late and the tetanus is in its most severe form, treatment is rarely given and the animal dies or is culled.
Prevention of bovine tetanus
Vaccines are available to protect against bovine tetanus which can last as long as three years if given in the correct doses at the correct times. These are usually used in areas of high risk. In these cases, vaccines are seen to prove economically worthwhile to farmers when compared to if the cattle were to actually become infected. Symptoms of the disease are generally milder in cattle that have vaccinated as opposed to those that have not.
In other cases, good hygiene is needed especially during and following operations such as castrations and calving. The spread of the disease can be reduced by ensuring that all surgical equipment are sterilised and the operation is undertaken in a clean area. Barbed wire which has rusted should be replaced as these can also act as a source of infection and any open wounds cleaned immediately.
Diagnosis of bovine tetanus
Signs and symptoms which are observed often lead to a positive diagnosis for bovine tetanus. Open wounds where the bacteria are thought to have entered can be used to produce cultures of the bacteria although, due to the complex nature of identifying this type of small bacteria, this method is rarely used.
The prognosis is almost always poor when the infection of unvaccinated animals has resulted in a full blown case of tetanus and so this usually leads to death.