Top Ten Equine ‘Strangles’ Guidelines

1. If you think your horse may have Strangles and need advice?

Call the practice on 01306 627 706. We will be able to offer some guidance and arrange for one of our vets to make a visit.

2. What causes ‘Strangles’?

Strangles is a highly contagious infectious disease of the upper respiratory tract. Strangles is caused by a bacterium called Streptococcus equi (S.equi) and affects horses, ponies and donkeys.

3. What are the main clinical signs?

• Depression and dullness
• Loss of appetite
• Nasal discharge
• Development of a cough
• High temperature
• Swelling of the lymph nodes (glands) under the jaw or on the head or neck which can lead to abscess formation at a later stage

The abscesses which cause the lymph nodes to swell may burst discharging highly infectious, creamy-yellow pus. In some cases the glands swell so much they restrict the airway, hence the name strangles.

4. What is the incubation period / when will I first see symptoms?

The incubation period of strangles is on average 7 to 14 days. However, because infected horses can shed the bacterium for long periods after symptoms have stopped showing, the interval of time between new cases in an outbreak can be up to 3 weeks or more.

5. How is it transmitted / passed between horses?

Strangles can be spread easily by direct contact between horses or indirectly by handlers, equipment or contamination of the environment. This can lead to large outbreaks with many horses becoming infected if strict biosecurity measures are not put in place and adhered to. For example, the infection can be spread:

• by direct contact such as nose to nose contact between horses
• via equipment shared with infected horses, such as:
• water troughs where the bacterium can survive for long periods
• feed buckets
• grooming equipment
• tack / clothing

6. How long can items such as grooming kits and buckets harbor the disease for?

On water buckets in particular, the bacteria can live for long periods, and up to approximately one month. However, using proper anti-bacterial cleaners such as Virkon will kill the bacteria quickly.

7. What can you use to clean your items to kill the Strangles?

Most anti-bacterial cleaners will be effective at killing Strangles. We have had success with Virkon which can be found here:

8. How is it diagnosed?

There are three main methods of diagnosis:

a) Swabbing is where three consecutive swabs are taken at weekly intervals and sent for testing in a lab.

b) Testing via endoscopy has been said to be the most reliable method. A sample is taken directly from the guttural pouch in the throat and sent for testing. This can also determine whether a horse is a carrier or not.

c) Blood tests identify if a horse has antibodies to the Strangles bacteria in their bloodstream. Antibodies are produced approximately two weeks following exposure to the bacteria and last up to six months.

Horses that have been exposed to the bacteria in the last six months will test positive.

9. What is the treatment and is there anything else I should be concerned about?

Treatment is a largely debated subject. Some say the bacteria should be left to run its course on its own without treatment, some say it should be treated aggressively with penicillin. This will be a joint decision with you as an owner and your vet.

There is a second form of Strangles called ‘purpura haemorrhagica’ which is associated with a previous bout of strangles. The head, legs and underbelly of the horse are most often affected and it also causes bleeding into the skin, gums (seen as areas of red spotting) and organs such as the lungs. It can prove fatal within a very short period of time and therefore an exceptionally quick diagnosis is very important.

A third form of Strangles also exists known as Bastard Strangles which can be a complication from the initial infection. It can be seen in the abdominal or lung lymph nodes which may develop abscesses and rupture, sometimes weeks or longer after the first infection seems to have resolved. In severe cases abscesses may rupture in the brain causing sudden death or abscess may burst in the throat and the pus will be inhaled into the lung.

10. How long will it take to recover?

On average the standard form of Strangles can take ten to fourteen days to run its course without drug intervention, this depends on the severity of the case and the general health of the horse at the time of infection. It should however be kept in mind that the bacteria may continue to shed after symptoms have left and therefore testing on more than one occasion after symptoms have gone is recommended.

Other queries?

Please call the practice and we would be happy to help.

Please also review the HBLB Strangles guidelines in the Codes of Practice ( and Strategy To Eradicate and Prevent Strangles (STEPS at

This guide is for information purposes only, if you suspect your horse may have strangles please call the practice and arrange a visit from a vet. The opinions presented in the Guidelines are subject to change and should not be considered to be a treatment recommendation for any individual patient. We cannot attest to the accuracy, completeness or currency of the opinions contained herein and does not accept any responsibility or liability for any loss or damage caused to any patient or any third party as a result of any reliance being placed on these Guidelines or as a result of any inaccurate or misleading opinion contained in the Guidelines.

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