Strangles is a highly contagious disease. It gains its name from the fact that affected horses can develop enlarged lymph nodes around the throat that restrict passage of food and in severe cases restrict breathing. Horses were emotively described as being ‘strangled’ by the disease in early veterinary books and the term has been adopted worldwide.

The disease is caused by a bacteria, Strep equi, and can be easily spread. Nose to nose contact between horses is an obvious source, but people, tack and equipment also have the ability to transmit infection. Water troughs can harbour infection for up to a month if contaminated with nasal discharge. Paddocks too, should be considered ‘dirty’ for a month after being used by affected animals. This is because both faeces and discharges can harbour bacteria.

Aerosol spread, where horses share the same confined air space, for example in an enclosed waiting arena or on a lorry, will transmit infection. Riding past infected premises should not pose a risk as long as horses are at least 25 metres away.

The incubation period following exposure is approximately 14 days although this can be up to 3 weeks in some individuals. Once infected, horses can remain infectious to others for up to 6 weeks in most cases. This period can be extended by months if the animal is not screened clear of disease and becomes a carrier.

Clinical signs include high temperature, dullness, sore throat and neck, enlarged lymph nodes around the jaw and throat and profuse nasal discharge. Some abscesses may rupture. Please remember not all these symptoms will appear at once or in every case.

ISOLATE suspect cases. Call us to take samples and start appropriate treatment. Pain relief is always necessary; antibiotic use will depend on each individual case.


Isolate the affected horse/s and set up strict bio security

Stop movements on or off yard and be honest – tell your neighbours.

Separate horses into three groups under veterinary supervision –infected group, suspicious group and unaffected group. Allocate individual people to one of the three groups only so there is no risk of a person spreading the bacteria.

Affected animals must remain within that group until PROVEN to be clear of infection. This requires either 3 naso pharyngeal swabs over a two week period or examination and lavage of the guttural pouches via endoscopy.

If affected animals are not screened they run the risk of becoming carriers and being responsible for future outbreaks.


Monitor horses closely and take daily temperatures- above 39oC or 102oF warrants discussion. If attending events of any sort in the future, avoid nose to nose contact with any other horses. Always take your own equipment with you when staying away from home at an event –never share buckets!

New horses coming to a yard should be isolated for 3 weeks – in a paddock preferably and 25 metres from others. A blood sample taken on arrival and again at the end of the isolation period will determine whether or not there has been exposure to infection.

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