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Strangles in Horses: Symptoms Prevention and Complications Explained

Strangles in Horses: Symptoms, Prevention, and Treatment

Horses are susceptible to a range of diseases, and strangles is one of the most common bacterial infections affecting equines. It is caused by the bacteria Streptococcus equi and primarily affects the lymph nodes in the head and neck of a horse.

Understanding strangles, its transmission, prevention, treatment, and complications is important for all horse owners.

Overview of Strangles

Strangles is a contagious bacterial infection that affects horses and is caused by Streptococcus equi. Strangles is highly contagious and spreads easily between horses through direct contact with infected animals, contaminated surfaces, or indirect contact through shared equipment.

The bacteria are released through nasal secretions and pus-filled abscesses that typically form in the horse’s lymph nodes in the head, causing them to swell.

Symptoms and Diagnosis of Strangles

The most common symptoms of strangles include fever, depression, and a runny nose. Infected horses will also develop swollen lymph nodes under their jawline, which can cause significant discomfort, difficulty swallowing, and breathing.

Nasty smelling pus-filled abscesses may also appear on the horses’ face and head. These abscesses and swollen lymph nodes can cause breathing difficulties in some horses, and this requires immediate veterinary attention.

Your veterinarian can diagnose strangles through clinical signs, including the presence of abscesses and swellings, laboratory tests, culture of pus, and blood work.

Transmission of Strangles

Strangles is a highly infectious bacterial disease, and one of the easiest ways it spreads is through direct or indirect contact. Direct transmission happens when a healthy horse comes into close contact with an infected horse’s nasal secretions, snot, pus, or saliva.

Indirect transmission can occur from an infected horse’s touch on shared equipment like water troughs or feed buckets. You can also inadvertently transmit the disease from horse to horse by using contaminated equipment or hands without proper disinfection practices.

Shedding bacteria is a major issue, even after recovery because, in some horses, the organism hides out in the guttural pouches.

Strangles Vaccine

A vaccine is the most effective way of protecting a horse against strangles. Two types of vaccines are available: modified-live vaccine and killed vaccine.

Modified-live vaccine is usually used in cases of high risk of exposure or an outbreak. The AAEP guidelines recommend this use in certain cases.

On the other hand, killed vaccines used as a preventative measure is required for horses that are at risk of strangles but have had no prior exposure to the disease. Core vaccination status may require a killed vaccine.

Always consult your veterinarian before starting a vaccine regimen.

When to Get the Strangles Vaccine

Horses that are in shared environments with other horses are at high risk for strangles.

This applies to horses in riding schools, competition stables, breeding farms, and those in shared pastures. Horses that are frequently moved from one location to another or travel to other competitions should also be vaccinated.

Outbreaks of the disease can pose a significant challenge in controlling its spread, and the horses at the affected site will require an immediate vaccination. Prudent horse owners also get their horse vaccinated after consultation with their veterinarian, especially if the environment the horse lives in has a known history of the disease or has a carrier.

Adverse Side Effects of Strangles Vaccine

Vaccines are meant to be safe and effective, but sometimes adverse reactions can occur. Strangles vaccine can cause an allergic reaction, which is rare.

Another complication is purpura hemorrhagica, which can result from exposure to the streptococcus equi organism. If a horse develops this, they will require medical attention as soon as possible.

Treatment and Recovery

Antibiotics, including penicillin, are the most effective treatment for strangles. Managing the swelling abscesses through draining with your veterinarian using sterile surgical technique is also vital.

Isolation of affected horses is also necessary during treatment and at the recovery phase to avoid spreading the disease. In some cases, treatment may also require handling a guttural pouch infection that can spread through the bloodstream and can potentially cause neurological damage if left untreated.

Complications of Strangles

Strangles is a severe bacterial infection, and horses that have been infected also face the risk of developing associated complications. Bastard strangles is a severe form of the disease that causes chronic abscesses in organs such as the lungs and liver.

Guttural pouch infections can occur if the infection spreads beyond the lymph nodes. Additionally, Purpura hemorrhagica is a severe complication that can result from strangles.

A horse with this complication experiences blood clots in the vessels leading to internal hemorrhaging, which can be potentially fatal if not immediately managed with treatment.


Strangles is a significant problem that affects horses in different settings. Fortunately, vaccines have been developed that effectively control it.

The use of vaccines and preventative measures, such as isolating affected horses, is crucial in ensuring healthy horse populations, avoiding disease transmission, and minimizing the spread of the disease. By familiarizing ourselves with the symptoms, prevention, and treatment options of strangles, we can keep horse populations safe and healthy, always.

Transmission of Strangles in Horses: Direct and Indirect Transmission and Prevention

Strangles is a highly contagious bacterial infection that is easily transmitted between horses. The disease is caused by the bacteria Streptococcus equi and primarily affects the lymph nodes in the head and neck of a horse.

As a horse owner, understanding the different modes of transmission of strangles is essential in preventing its spread.

Direct Transmission of Strangles

The most common mode of transmission of strangles is through direct contact between horses.

Strangles spreads when an infected horse comes into close contact with a healthy horse. When the healthy horse comes into contact with nasal secretions, pus from abscesses, or saliva from the infected horse, the bacteria can easily transfer from the infected horse to the healthy one.

This level of contact might include horses rubbing noses, touching their noses together, or being ridden or groomed by someone who has touched an infected horse. Carrier horses present another mode of direct transmission of strangles.

Horses that have had a previous infection but have recovered and no longer show any signs of illness can still carry the bacteria in their guttural pouch. Carrier horses may not show any symptoms of the disease, but they are still carriers, and the bacteria can be easily spread through direct contact with other horses.

Indirect Transmission of Strangles

The transmission of strangles between horses can occur indirectly through contact with contaminated surfaces. Such surfaces may include water troughs, feed buckets, grooming equipment, or even staff hands or clothing who have come into contact with an infected horse.

The affected horse excretes bacteria through nose discharges, pus from abscesses, and, as mentioned, fecal matter in carriers. The bacteria can survive on surfaces such as blankets, fences, water troughs, or other shared facilities.

Environmental survival, especially if the conditions there are humid and dark, can make transmission potentially higher.

Prevention of Strangles Transmission

Understanding the modes of strangles transmission pinpoint ways to minimize its spread. Here are some of the prevention measures:

Cleaning and Disinfection

One of the ideal ways to slow down or halt the spread of strangles is through cleaning and disinfecting of shared spaces when a case shows up. Clean stalls, water troughs, and feed buckets regularly, especially when a new horse arrives at the stable.

Disinfect shared grooming equipment like brushes and leads to avoid contamination between horses. Your stable should also have areas designated for isolation to be used if a horse is found positive for strangles.


If a horse arrives at your stable, a quarantine period should be put in place, irrespective of whether the horse is showing any signs of disease. Ideally, for two weeks, new horses should be kept isolated or monitored to ensure they neither present the disease nor are carriers.

Changing Clothes and Showering

It is crucial to enforce a policy of having staff or a person handling horses wash their hands and clothes thoroughly, especially if they have handled sick horses or been in contact with equines from outside an establishment. Staff should shower before handling healthy horses after contact with sick horses.

All bedding and clothing should be laundered on the hottest setting possible to ensure all bacteria is removed.

Keeping Infected Horses Isolated

Isolation of infected horses is key to prevent within-stable spread of the disease. It is vital that you minimize contact between infected horses and healthy horses in the stable at all times.

Your veterinarian might recommend different quarantine procedures, but it could include strict isolation procedures such as using separate premises, designated grooms, and biosecurity protocols that should limit or stop transmission.

Diagnosis and Treatment of Strangles

Timely diagnosis and treatment of strangles is essential in ensuring a successful recovery and preventing the further spread of the disease. Working together with a qualified veterinarian is necessary as they can make a precise diagnosis and administer the required antibiotics.

Diagnosis of Strangles

Strangles can have severe and potentially life-threatening complications if left untreated. Your veterinarian can diagnose strangles through clinical signs and trained diagnostic skills.

A veterinarian will examine the horse and take into consideration medical history, clinical signs, and laboratory tests such as blood work. They may take samples of abscesses for culture and sensitivity tests to identify the specific strain of bacteria causing the disease.

If required, a filter paper or wash sample taken from the guttural pouch might be taken to test for carrier state or persistent infection (post-strangles).

Treatment of Strangles

Antibiotic treatment is the most effective treatment for strangles, and choosing the right antibiotic will depend on the severity of the infection and the horse’s clinical condition. The use of penicillin for three days stands as the standard treatment for horses with streptococcus equi infection and might be indicated for those exposed to disease.

Before treatment, abscesses should be evaluated by your veterinarian, and surgical draining should be performed if necessary to avoid the rupturing of abscesses.

Quarantine of infected horses during and after treatment is necessary to minimize disease transmission.

Recovery from Strangles

It is essential to monitor infected horses for at least three weeks after the last abscess has ruptured and ensure their environment is free of the bacteria. Once recovered, it is necessary to monitor infected horses for a period of up to several months, depending on whether or not there was guttural pouch involvement with the infection.

The risk of developing complications in recovered horses underscores the importance of close monitoring by a veterinarian following strangles episodes.


Strangles remains a highly contagious bacterial infection that can cause significant distress on infected horses and the entire stable. Timely diagnosis, treatment, and prevention measures are crucial in ensuring the proper care of the infected horse and controlling the spread of the disease.

Understanding direct and indirect modes of transmission of strangles and how to prevent them is an important step in keeping your herd healthy. A collaborative approach among veterinarians, horse owners, and stable managers is essential in controlling this disease and managing its consequences.

Complications of Strangles: Bastard Strangles, Purpura Hemorrhagica, Guttural Pouch Infections, and Can Humans Get Strangles from Horses?

Strangles is a highly contagious bacterial infection that can spread rapidly in a stable.

While it is not usually fatal, complications can arise, leading to severe and life-threatening situations. Understanding the possible complications can help you monitor your horse’s health and manage strangles better.

Here, we’ll discuss bastard strangles, purpura hemorrhagica, guttural pouch infections, and the possibility of horse-to-human transmission of the disease, among others.

Bastard Strangles

This is a severe complication of strangles that occurs when the bacteria spread beyond the typical lymph node sites. The spread can occur through contaminated discharges or bloodstreams of infected horses.

As the bacteria spread, abscesses form in organs such as the lungs, liver, spleen, and kidneys. Treatment for bastard strangles should involve hospitalization and the use of potent antibiotics.

A veterinarian will choose the medication after assessing the specific bacteria strain present and based on drug sensitivities.

Purpura Hemorrhagica

Purpura hemorrhagica is a severe immune-mediated response to strangles bacteria. In some cases, it occurs after the animal has recovered from primary strangles.

The condition causes systemic inflammation, resulting in leakage of fluid from vessels leading to the formation of edema. Skin inflammation, hives, and swelling of limbs and head occur in these horses.

Treatment typically involves the use of steroids to reduce inflammation and edema.

Guttural Pouch Infections

The guttural pouch is an air-filled sac located at the back of the horse’s nasal cavity. The pouch is a low-oxygen environment that provides a good breeding ground for bacteria.

If bacteria enter the guttural pouch during strangles infection, it can cause a secondary infection. When the bacteria remain in the guttural pouch, it is normal for horses to become carriers of the disease, which makes monitoring of recovered horses important.

Can Humans Get Strangles From Horses?

While strangles typically only affects horses, humans can contract lower-level disease caused by the zooepidemicus subspecies of Streptococcus equi, which causes a more minor level of respiratory symptoms.

Specific measures need to be taken to avoid transmission, especially personal hygiene precautions. Systematic use of gloves and masks for staff handling sick horses can limit transmission of the disease.


Strangles is a severe bacterial infection that affects horses and can lead to significant complications. Conditions such as bastard strangles, purpura hemorrhagica, and guttural pouch infections can be serious and require prompt medical intervention.

Horse owners should ensure that their horses receive prompt attention when any symptoms arise and be conscious of their recovery period to manage the disease’s long-term implications. Personal hygiene precautions in humans need to be observed when handling sick horses to avoid zooepidemicus subspecies’s minor levels of respiratory disease transmission.

A proactive approach to strangles’ management assures the health and well-being of equine animals in the stables. In conclusion, strangles is a highly contagious bacterial infection that can lead to severe complications in horses.

Direct and indirect transmission and prevention measures are instrumental in controlling and managing the disease spread. Early diagnosis, prompt treatment, and close monitoring to avoid complications such as bastard strangles, purpura hemorrhagica, and guttural pouch infections are vital.

Ensuring proper management protocols and biosecurity promotes a healthy equine population free from strangles infections.


  • What is strangles?
  • What is the importance of strangles vaccination?
  • How is strangles transmitted, and how can it be prevented?
  • What are the treatment and recovery process for strangles?
  • Finally, what are the possible complications of strangles, and can humans get vaccinated?

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