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Strangles – Control the spread!

St David’s Equine Practice

Strangles bacteria is extremely infectious and it is thought that even a single bacteria may be enough to cause disease in a naïve horse. For this reason, it is important that yard biosecurity on an infected yard is very strict.

Infection with the bacteria is by contact with the organism. This contact can be either direct (close contact between infected and susceptible animals) or indirect (contact with shared equipment, feed buckets, tack, stabling, water sources and on clothes or hands of people caring for the horses that has been contaminated by the nasal secretions of an infected horse).

The incubation period is 7-14 days but can extend to 21 days. Horses may spread the infection before showing signs of the disease and there can be an interval of up to 3 weeks between cases as infected animals shed the bacteria for long periods, even after they appear to have recovered.


Early diagnosis, good communication and excellent hygiene are key to the control of strangles.

It is important not to hide the fact that a horse may be suffering with strangles or to delay calling your vet as this will inevitably cause bad feeling on the yard and in the local area and will aid the spread of the disease.

If you suspect that your horse may have strangles it is vitally important to isolate it immediately and call your vet. It is also sensible to isolate any horses that have been in direct contact with the affected horse from those that have not. Strict hygiene must be adhered to by everyone on the yard – this is time consuming and inconvenient but absolutely necessary to prevent the spread of strangles through the yard.

The yard must be closed with no horses coming on or going off the yard. All owners and grooms should be made aware of the situation as soon as possible. Ideally people who handle affected or potentially affected horses should not handle any other horses. If this is unavoidable, they must disinfect their footwear, change their clothing and thoroughly wash their hands with an antibacterial wash in between animals. Waterproof clothing that can be disinfected or disposable boiler suits are useful.

All horses on the yard should be closely monitored and ideally have their temperature taken twice daily. Any horses showing a raised temperature should be examined by a vet.

It is important to have coordinated management of the whole yard by one individual such as a vet or yard manager even if the horses are under the care of different vets.

The yard should not reopen until all horses on the yard have had 3 clear nasopharyngeal swabs over a 3 week period or a negative bilateral guttural pouch lavage and a single negative nasopharyngeal sample taken at the same time.


A vaccination given into the mucosa of the upper lip was available for a short time, but has now been withdrawn from sale. A new intramuscular vaccine is undergoing trial at the Animal Health Trust and is likely to be available at some point in the future.

Until an effective vaccine is available, the only reliable method of prevention is strict yard biosecurity. This can take the form of temporary isolation of new horses coming on to a yard and blood sampling to identify potential carriers of the disease before they mix with other horses.

General routine hygiene measures are also important such as the use of separate and dedicated equipment for horse and the regular cleaning and disinfection of shared water troughs.

St David’s Equine provide the equine veterinary services for Molecare Veterinary Services. www.stdavids-equine.co.uk