VACCINATIONS

Our recommendation, is that all horses are routinely vaccinated against tetanus and strangles. Both of these diseases are reasonably common and both can be severe or fatal. When regular boosters are given, protection following vaccination is generally excellent and will prevent illness or at the very least, reduce the severity of clinical signs and/or the duration of illness.

 

From a herd perspective, vaccination will decrease shedding of disease if there is an outbreak and minimise transmission to naïve animals in the herd/stable environment. Some horses have increased susceptibility to disease and particular care should be given to ensuring their vaccinations are up to date. Horses to pay particular attention to include neonates, weanlings and geriatric horses with Cushings induced immunosuppression.

The organism Clostridium tetani is endemic within the environment and lives in soil and manure. This bacteria enters the body through wounds and multiplies in sites where there is poor oxygen supply. For example, an unvaccinated horse that stepped on a nail would be at particular risk.

This bacteria produces a powerful nerve toxin which causes muscle stiffness and spasm. The time from when the bacteria begins producing toxins to the first signs of tetanus is between 1-3 weeks. This bacterial disease causes a devastating fatal tetany in approximately 80% of infected horses. Treatment is expensive, labour intensive and beyond the financial capacity of the vast majority of owners.

The good news is that tetanus vaccination is affordable and highly effective. There are two products on the market that provide protection against tetanus. Equivac® TAT is a tetanus anti-toxin product. This product will provide approximately 3 weeks of protection in the face of an initial challenge. For example, if you immediately administer this product to an unvaccinated horse when it sustains an injury, the horse will be afforded some degree of protection. Equivac® T is a vaccine used to immunise horses against tetanus. It stimulates a strong and durable immunity against tetanus. Two shots given 4 weeks apart will provide 12 months of immunity. A booster shot should be given every 12 months.

Strangles is caused by the organism Streptococcus equi and is a highly infectious disease of the upper respiratory tract and lymph nodes of the head. Within 3-8 days of becoming infected, the horse will have a fever of between 39.5° and 40.5°C. The lymph nodes of the head will become swollen and painful and may burst and discharge a thick creamy yellow pus. The throat and larynx become very inflamed and swallowing food or water is difficult if not impossible for infected horses.

3-10% of infected horses will die as a result of strangles disease. 20% of infected horses will develop complications including dyspnea (difficulty breathing that may necessitate a tracheostomy), abscessation of organs within the body, persistent guttural pouch infection, pneumonia and purpura hemorrhagica (immune mediated disorder).

Unfortunately, there is no product that provides immediate short-term protection against strangles should an outbreak occur. The best defence is vaccination against the disease. The strangles vaccine is not as effective as the tetanus vaccine and occasionally, the disease will occur in horses that have been vaccinated. Fortunately, there is no doubt that vaccination will reduce the severity of clinical signs and duration of illness at the very least.

Equivac® 2in1 is a combined tetanus and strangles vaccine used for the prevention of tetanus and control of strangles. Equivac® S is a strangles vaccine used for the control of strangles.

To vaccinate your horse against both tetanus and strangles, please use the following protocol; Equivac® 2in1 followed by Equivac® S two weeks later, followed by Equivac® 2in1 in another two weeks. An Equivac® 2in1 booster should be given in 12 months. This protocol can be started when a foal is 12 weeks of age.

Whilst the duration of immunity against tetanus (after the first 12 month booster shot) is at least 12 months, the duration of protection against strangles can be much shorter. Horses will require an Equivac® S booster shot at least every 12 months. Horses in high risk situations may require an Equivac® S booster every 6 months. A horse may be considered at high risk if it competes regularly at competitions and/or is agisted at a property where horses frequently come and go.

Vaccinations are given by intramuscular injection in the side of the neck. The products mentioned above are manufactured by Zoetis.

It is important to recognise that commercial vaccines maintain their efficacy and have fewer side effects when the cold chain is preserved. Vaccines should be stored between 2° and 8°C (refrigerate).