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All About Strangles

One of the most common infectious diseases to strike horses is strangles. The bacteria, Streptococcus equi, causes an infection of the upper respiratory tract. The disease is often mild, resulting only in nasal discharge, a raised temperature, loss of appetite and swollen glands. Indeed, mild cases, may go almost unnoticed. But some horses which are infected with strangles will become more seriously ill.

Serious Infections

Horses can go on to develop abscesses of the lymph nodes, often those located under the jaw or behind the cheek. These abscesses are the signature symptoms of the disease and may rupture which is why the condition is known as strangles. In severe cases, serious complications can develop.

Abscesses may also form in the lymph nodes elsewhere in the body. This can prolong the disease and the treatment regime. Further complications can include purpura haemorrhagica, a limb swelling which is often accompanied by little red spots on the gums. This happens because the immune system has reacted in response to the infection. Strangles proves fatal in around 1% of cases.


Up to 10% of horses which recover from strangles become carriers of the disease. The bacteria sit in the guttural pouch and horses will continue to pass the bacteria on to other horses for months or sometimes years.

How to Prevent Strangles

The chief issue with strangles is that the disease spreads rapidly. Happily, it is easy to kill the offending bacteria. It is simple, but time consuming, to avoid infection by employing basic biosecurity measures. The disease can be spread via tack, clothing, shared drinking water, shared feed and pets such as cats and dogs hanging around the yard.

Diagnosing Strangles

It is possible to have a blood test to diagnose strangles but confirming the disease can be problematic. The bacteria do not grow well outside of the body, so it is sometimes necessary to test repeat samples. A single test will merely reflect whether the horse has antibodies to the disease, not whether the disease is active. Horses which have recently contracted strangles may not even have sufficient antibodies to show up in the test.

It can take around two weeks for antibodies to develop after infection and so blood tests at an early stage can return negative results. If infection is suspected, then a repeat test should be undertaken after two weeks. Following an infection, the antibodies will remain in the body for several months. It is also possible for antibodies to be present without the infection having been or becoming active. All of this means that interpreting the results of tests can be difficult.

A complete health check including a full scoping of the horse is often the best way to confirm a strangles infection. It may be necessary to take a swab from the throat (via the nose) or from abscesses to confirm a clinical diagnosis.

If you suspect strangles it is important to contact your vet as soon as possible.


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