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.