How to protect your horse from strangles

Strangles, which is a contagious bacterium, causes great concern for both horses and horse owners. Here, Agria gives tips on how you can actively work with infection prevention measures to protect your horse.

Today, most horses are vaccinated against influenza, which means that strangles is 10 times more common than flu infections.

What are the symptoms of strangles?

Fever
Impaired general condition
Nasal discharge, often thick, purulent
Cough
Enlarged, tender lymph nodes
Decreased appetite

In classic strangles, the horse has a reduced general condition, high fever, cough and purulent nasal discharge. The lymph nodes between become swollen, sore and an abscess can eventually burst open.

Fever, cough and nasal discharge, symptoms like with any cold, can be strangles. This means that it can be easy to miss outbreaks of the disease, especially with milder symptoms.

Is strangles contagious?

Strangles is highly contagious and can be spread directly or indirectly - directly by a sick horse being able to greet other horses, for example by standing next to each other in the stable, or walking in the same pasture. The infection can also be spread indirectly, through people, furnishings, water tanks/buckets or tools that have been in contact with infected horses.

It is not certain that everyone will get sick or show symptoms - it depends on how close contact they have had with the infected horse and how much resistance they have. To detect any new cases of disease as soon as possible, you should temp all horses 2 times a day. Horses usually get a fever 2 - 3 days before they become contagious in strangles.

The incubation period, i.e. the time from the time the horse encounters the infection to when it falls ill, is 3-14 days.

What causes strangles?

"Strangles is an infectious disease caused by a streptococcal bacterium"

Strangles is a notifiable infectious disease caused by a streptococcal bacterium, Streptococcus equi. The bacterium is found in the nasal secretions of sick horses and is spread when a sick horse coughs and snorts. The bacterium is also found in the pus from ruptured lymph nodes.

There are also horses that carry strangles bacteria chronically, most commonly in the air sacs. These horses are asymptomatic carriers and can infect other horses.

Consequences of strangles

So-called discarded strangles is a complication of strangles, which is due to the bacterium that causes the disease spreading to lymph nodes in internal organs and giving rise to abscesses. The symptoms can then be recurrent fever, colic and affected breathing. In the worst case, the condition can lead to death.

Another complication of strangles is anesarctica. Anasarca is a hypersensitivity reaction that causes inflammation of blood vessels. Symptoms include patchy oedema (fluid accumulation) on the body, oedema on the underside of the head, legs and abdomen, as well as punctuated bleeding on the mucous membranes of the mouth, eyes and nasal cavity, for example. Anasarca can also cause death through organ failure and circulatory collapse.

Anasarka, the hypersensitivity reaction, can occur as a result of other bacterial infections.

How is usability affected?

Unless the horse suffers any complication to strangles, most people will be completely recovered. Consult your veterinarian about how quickly you can start training your horse again.

Preventive

Age of the horse

Young horses and especially foals are extra susceptible to infections, as their resistance is poorer than adult horses. They should therefore be kept away from competition horses that travel a lot and encounter many infections. Breeding mares and old horses should also be protected against unnecessary infections.

New horses

New horses always involve a risk of infection. Therefore, it is good if you can arrange some type of quarantine for new horses, before they are taken in among the other horses. A new horse should be kept separate from other horses for 3 weeks.

If the horse has not shown signs of any contagious disease during that time, there is little risk that it will bring infection to the other horses. While the horse is in quarantine, it should be tempted 2 times a day, as fever is an early sign of infection.

If you have had an infection in the stable, you should consult your veterinarian about the need for cleaning and disinfection. The strangles bacterium can survive for several months in the stable environment if the temperature and humidity are right.

Clean and disinfect horse transports that have been used to transport sick horses - they can otherwise act as effective spreaders of infection. A good disinfectant is Virkon-S.

Think about the risk of infection at competitions and training

When you go and train or compete with your horse, you expose it to the risk of infection. To avoid your own horse spreading infection, you should not go if you have or have had sick horses at home in the stable close to the competition. If you are unsure of what to do, you should discuss with your veterinarian before going to the competition site.

To keep in mind:

Avoid having competition horses together with young horses and broodmares.
Quarantine new horses before they are taken in among other horses in the stable.
Clean and disinfect horse transports used to transport sick horses.
Do not go and compete if there have been horses with fever or nasal discharge in the stable recently. Consult your veterinarian in case of doubt.

How to protect your stable from the spread of infection

Vaccinating horses against strangles

Vaccination against strangles has been available in Sweden since 2022. The vaccine is given through two primary vaccinations. Revaccination (booster) takes place according to the veterinarian's recommendation based on the prevailing risk of infection every 6 to 12 months and can be given at the same time as the influenza vaccine.

1
In case of suspected strangles, sick horses should be isolated from other horses as soon as possible. By doing so, the risk of the infection spreading further is reduced. The isolated horses must be cared for by a person who has no contact with other horses.
2
Contact your veterinarian as soon as possible. The veterinarian examines horses with symptoms and assesses what measures need to be taken. If the veterinarian also suspects strangles, the county veterinarian must be contacted and the entire stable must be isolated.
3
Be careful with hygiene and minimize the number of people who have contact with sick horses. It is important to wash your hands thoroughly and to change shoes when leaving the stable. Before visiting other stables, you should also change all clothes.
4
Temp all horses in the stable daily. This makes it easiest to detect any new cases of disease.
5
Disinfect all equipment that has been in contact with sick horses. Horse transports used to transport sick or suspected infected horses must also be cleaned well and disinfected, for example with Virkon-S.
6
Inform everyone who is in the stable and put up clear information outside, so that stable visits by unauthorized people are avoided.

Diagnosis and treatment - What does the vet do?

The veterinarian forms an opinion of how the disease has manifested itself so far, by asking what symptoms the horse has had, whether more horses have fallen ill and where they suspect that the infection has come from. The horse's general condition is examined, the appearance of any nasal discharge is noted, the temperature is taken and the lymph nodes between the ganaches are examined.

The vet also listens to the heart and lungs and may try to provoke coughing by pushing the horse over the throat.

If strangles is suspected, a sample is taken to cultivate the strangles bacterium, Streptococcus equi. The sample can be taken by stroking a swab against the mucous membrane of the nasal cavity or performing a nasal irrigation. You can then take samples further into the airways from the air sacs. Repeated sampling of several sick horses is often required for the bacterium to be detected. A negative test result is therefore no guarantee that it is not strangles. The strangles bacterium is usually detected by a so-called PCR method. A blood test to examine how severe the infection is can also be taken.

Some horses may need treatment in the form of, for example, fever-reducing, anti-inflammatory medication. In some cases, the veterinarian chooses to start treatment with antibiotics.

Strangles is a notifiable disease, which means that if the veterinarian after his examination suspects strangles, he or she is obliged to report it to the county veterinarian and isolate the stable. The isolation means that no horse may be moved to or from the stable (except to isolation stables/animal hospitals) and that no more people than necessary should stay in the stable, as they can bring the infection to other stables.

This is an example of how an investigation can be done. Different veterinarians may choose to perform it in slightly different ways.