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Strangles What is Strangles? Strangles is an acute, infectious disease in horses caused by the bacterium Streptococcus equi. It is a common condition that may result in upper airway constriction (Strangles) due to the enlargement of the lymph nodes of the head and neck. It can affect horses of all ages and types but those most at risk are:
Having an incubation period of 4-10 days and a clinical course, if untreated, of about 3 weeks, it is highly contagious and can be fatal in 1% of cases. Approximately 10% of horses that recover can become carriers showing no clinical symptoms but can be a source of infection. Once inside a stable or yard, strangles can spread quickly through direct contact between horses or indirect contact e.g.via shared drinking and feeding equipment and tack. Infection is usually restricted to the head and neck; however, in up to 10% of cases it can develop in other body organs and cause abscesses. This is known as "bastard" strangles and horses rarely fully recover. What are the symptoms? Strangles is characterised by:
The clinical signs may be obvious but your veterinarian's diagnosis is always needed as a horse may show some of the above symptoms but have a different condition. Further investigation may be required which involves 3 nasopharyngeal swabs taken a 5-7 day intervals over a 2 week period. Can it be treated? If the disease is diagnosed at an early stage then your veterinarian may decide to treat with antibiotics. However, if the diagnosis takes place after abscesses have formed ten your veterinarian may need to lance them to encourage draining. What should I do if it happens? Suspects should be isolated. All other horses on the yard are at risk so should be monitored closely. The yard should be closed to horses from the outside. There should be thorough cleaning and disinfecting of contaminated housing and environment. People who are in regular contact with horses from outside of the yard should keep off the premises thus meaning the yard could be closed down possibly for months. What are some preventive measures? One can take several steps to minimise the risk of strangles. Try to avoid contact with horses of unknown origin. Make sure your yard does not become overcrowded. Quarantine new horses to the yard for a few weeks. A vaccine to control strangles is now available called Equilis StrepE. What does the vaccination involve? The vaccination reduces the clinical symptoms of strangles and the occurrence of lymph node abscesses in horses that are at high risk of infection such as horses in livery yards, horses at the sales, competition horses and horses on outbreak areas. The vaccine is administered by injecting into the upper lip of the horse. The vaccine can be given to foals from four months of age and 2 injections should be given at a 4 week interval. It has a 3 month duration of immunity after the 2nd injection and horses in high-risk situations should be re-vaccinated with a single dose 4 times a year. Medium risk horses are vaccinated every 6 months but a booster should be given immediately if an outbreak occurs and it has been more than 3 months since the last vaccination. There is generally no need to vaccinate horses in a low risk situation.
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