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Strangles is one of the most common diseases diagnosed (accountable for 30%) within the equine community worldwide, is caused by the Streptococcus equi bacteria and can affect any horse of any age, breed and condition, although it appears to be more severe in younger horses (under the age of 5). Strangles is more common in winter and is currently fatal in about 1% of cases. One of the problems with Strangles is that its symptoms are not immediate and so tend to display visually between 3-14 days after the horse has come into contact with it. Unfortunately, this is why the disease spreads so rapidly because horses continue to socialise and be in close proximity with other horses during this ‘incubation’ period. It is quite scary how easily this infection can be spread, for example:

·         Nose to nose contact between horses

·         Equipment shared with infected horses – feed, tack, buckets, brushes and water troughs

·         Shared water troughs – the bacteria can live in the water troughs for up to 4 weeks.

·         Handlers, farriers and vetinary surgeons can also transfer the infection from horse to horse if precautions are not taken.

·         It is therefore recommended that it an outbreak occurs only one person on the yard be responsible for the treatment and day to day management of the horse to prevent spreading the disease which can also be transmitted on clothing.

 

·         Loss of appetite, even anorexia.

·         Not appearing to be usual self, (horses may start to lower their heads and try to stretch their necks at the same time to relieve any throat and neck pain), depression etc

·         Fever of between 39 to 41 degrees Celsius

·         Nasal discharge,

·         Occasionally a cough develops.

·         Swelling of the lymph nodes under the jaw or neck within about a week of the above symptoms beginning.  These swellings are abscesses which when they burst after about 7-14 days, allow a thick yellow puss to escape which is highly infectious. It is these swellings that give the disease the name strangles - if the swelling is severe it can restrict the airway of the horse and affect their breathing. Once the abscesses have burst your horse will generally then start to show quick signs of recovery. The rupturing can be encouraged by applying a hot compress to the swellings and then flushing the cavity with antiseptic.

 

Recovery can take between 1-4 weeks depending on the severity of the disease. It should be noted that a horse can carry the infection for up to 8 months after it appears to have made a full recovery.

·         Inflammation of the heart muscles may occur almost immediately after the infection has passed. Your vet can do an electrocardiogram to detect this and also to determine whether your horse can return to training or heavy work following the strangles infection

·         Inflammation of the subcutaneous tissue to the head.

·         Paralysis of the throat muscles (laryngeal hemiplegia) also known as ‘roaring’.

·         Anaemia

·         Chondroid - Recurring infection in the guttural pouch which can lead to the dry pus from the abscesses becoming exceptionally hard resulting in the horse becoming a carrier of the infection.

·         In a few cases (approximately 8%-10%) the abscesses may travel down into the horse’s body rather than restricting itself to the head and neck. This results in what is termed ‘bastard strangles’ whereby abscesses can unbeknownst to the owner develop in the brain or throat which when they burst means that your horse’s recovery prognosis is minimal as this can be fatal.

·         Rarely the disease can become ‘purpura haemorraghica’ which is when the gums and major organs such as the lungs can start to bleed due to inflammation of the blood vessels. It can also result in a swelling of the limbs and head. This complication is more common in the younger horse and can also be fatal, but is rare.

Horses which do not develop chondroid will remain infectious for up to 6 weeks from recovery as the infection is shed from their mouth and nose.

In Britain your vet will not necessarily vaccinate for the disease itself but will provide medication to control the horse’s temperature. The use of antibiotics is controversial, not least because it gives a false sense of security – often horses that have completed a course of antibiotics can subsequently develop the swellings and abscesses and risk infecting other animals again. It can also mean that the horse becomes a carrier of the infection for other horses. Some countries do vaccinate against Strangles but these vaccinations have not proved to have any long term benefits as it only protects the horse for a few weeks at a time. It should also be noted that despite the widespread vaccination programme in countries such as the USA, Australia and Canada, strangles remains a very common equine disease. However, research in the UK is ongoing with four major institutions; The Animal Health Trust, The Sanger Centre, The University of Newcastle upon Tyne and The Cambridge University. In addition to this in 2004/2005 over £2million in grants was awarded to the Home of Rest for Horses to investigate ways and means of controlling strangles and produce the equine antibody to fight the S.equi bacterium which will be a major step in creating an effective vaccine. There have also been several campaigns in recent times such as the ‘Breaking the Strangles Hold’ campaign that raised £250,000 in two years to tackle the stigma associated with this infection.

 

There is some good news in that approximately 75% of horses who recover completely from strangles develop an immunity to it naturally which can last for 5 years or more.

 

www.animed.co.uk states that ‘From 1^st March 2008 the Animal Health Trust is offering a new blood test which will distinguish the horses that have been exposed to the S.equi during a strangles outbreak and may of become carriers. It can be used to screen horses prior to movement, competition or sales etc. Further details can be found at www.aht.org.uk.’ The results from this test are available within 24 hours.

Hygiene plays a vital role in controlling the spread of this infection, just as it does in our hospitals today, and is no less important.

·         Immediately iscolate any horse that presents with a nasal discharge and call your vet immediately for a swab.

·         Regular disinfecting of all food and water troughs and containers, clothing, stabling and equipment by infected horses (Virkon has proved to be a good disinfectant to use in this situation). This also includes the stable walls, doors, gates and trailers, forks and wheelbarrows. Steam cleaning is particularly effective as the bacteria can survive in temperatures up to 60 degrees Celsius.

·         Quarantine new animals on your yard for no less than 2 weeks – new animals are the primary cause of an infection outbreak on livery yards. After 2 weeks without any symptoms the new horse is a very minimal risk to other horses.

·         Prepare foot dips for people to use on exiting the quarantine area and if possible use gloves when handling infected horses. Also ensure that arms and hands are washed thoroughly on leaving the quarantine area.

·         Burn bedding of infected horses or compost it under a plastic sheet to prevent the spread by flies.

·         Flies can carry the infection from horse to horse so especially during the hotter months all horses and equipment should be protected as far as possible from flies.

·         Rest contaminated pasture for 4 weeks before allowing another horse to graze there.

·         No in-contact animals should leave the yard. Equally, no new animals should be brought in.

·         Infected or in-contact animals should not be released from isolation until 3 negative nasopharyngeal swabs have been taken over a 2 week period by your vet.

·         Isolate any animal who has now recovered from strangles for as further 6 weeks while the remaining infection is shed from their nose and mouths.

 

The Scottish Strangles Strategy Group has created a voluntary code known as STEPs (Strategy to Eradicate and Prevent Strangles) which can be downloaded from www.strangles.org

52484 BHS leaflet no 13 Strangles 22/03/05