Strangles in Michigan Threat to Horses and How to Respond

Overview of Strangles

Strangles, also known as equine distemper, is a highly contagious bacterial disease that affects horses. Caused by the bacterium Streptococcus equi subsp. equi, it is characterized by swollen lymph nodes, nasal discharge, and fever. Strangles can be severe, causing significant distress to affected horses and leading to complications if not managed properly.

Recently, Michigan has seen cases of strangles emerge, raising concerns among horse owners and equestrian communities. Two horses in the state tested positive for the disease, prompting increased vigilance and a call for preventative measures. This article explores the implications of these cases, the nature of strangles, its transmission, symptoms, prevention, and response strategies.

The Cases in Michigan

The Michigan Department of Agriculture and Rural Development (MDARD) confirmed that two horses had tested positive for strangles. Both horses are under veterinary care, and the premises where they reside are under quarantine. The affected horses’ owners are taking steps to limit the spread of the disease, including isolating the animals and implementing biosecurity protocols.

The detection of strangles in Michigan is a reminder of the importance of maintaining a healthy equine population through good husbandry practices and early detection of diseases. Given the highly contagious nature of strangles, this outbreak serves as a wake-up call to horse owners, trainers, and veterinarians throughout the state to be vigilant and proactive in their efforts to prevent the spread of this disease.

Understanding Strangles

Strangles primarily affect the upper respiratory system of horses, leading to symptoms like fever, nasal discharge, and swollen lymph nodes in the throatlatch area. The bacteria that cause strangles can spread through direct contact with infected horses, contaminated equipment, or even through the air. It can also spread via humans who have come into contact with infected horses and then touch other animals without proper hygiene.

In severe cases, the lymph nodes may abscess and burst, leading to further complications and a risk of secondary infections. Horses of all ages can contract strangles, but younger horses tend to be more susceptible. The disease has an incubation period of about 3 to 14 days, making it challenging to detect early and contain.

Symptoms of Strangles

Identifying the symptoms of strangles early is crucial for preventing further spread. Common signs of the disease include:

  • Fever
  • Nasal discharge (initially clear, becoming thick and yellowish-green)
  • Swollen lymph nodes, especially in the throatlatch area
  • Difficulty swallowing or breathing
  • Coughing or wheezing
  • Lethargy or reduced appetite

Horses displaying any of these symptoms should be isolated immediately and examined by a veterinarian. Early detection can help prevent severe complications and minimize the risk of spreading the disease to other horses.

Transmission and Containment

Strangles can spread through several pathways, making containment a significant challenge. The most common methods of transmission include:

  • Direct contact: Infected horses can pass the bacteria to healthy horses through nose-to-nose contact or sharing of feed and water sources.
  • Indirect contact: Equipment, tack, grooming tools, and even human hands can carry the bacteria from one horse to another.
  • Aerosol transmission: Although less common, strangles can spread through respiratory droplets when an infected horse coughs or sneezes.

Containment involves a combination of quarantine, sanitation, and biosecurity measures. If a case of strangles is suspected, the following steps are recommended:

  • Isolation: Infected horses should be isolated from healthy ones to prevent direct contact and limit the spread of bacteria.
  • Sanitation: Thoroughly clean and disinfect all equipment, tack, stalls, and surfaces that may have come into contact with infected horses.
  • Personal hygiene: Handwashing and changing clothes between handling horses can reduce the risk of indirect transmission.
  • Quarantine: Limit movement of horses in and out of the affected area until the outbreak is under control.

Preventative Measures

Prevention is key to managing strangles in horse populations. Here are some strategies to help reduce the risk of an outbreak:

  • Vaccination: While no vaccine is 100% effective, vaccination can reduce the severity of strangles and limit their spread. Consult with a veterinarian to determine the best vaccination strategy for your horses.
  • Biosecurity: Implementing strong biosecurity measures, such as requiring visitors to wear clean clothing and disinfecting equipment regularly, can help prevent the introduction of strangles to your property.
  • Monitoring: Regularly monitor horses for symptoms of illness and report any unusual behavior or signs of sickness to a veterinarian.
  • Travel precautions: If you’re traveling with horses, ensure they are healthy before leaving and follow biosecurity protocols when visiting other facilities or attending events.

Response to an Outbreak

When an outbreak occurs, swift action is crucial to limit the spread and protect the health of horses. The following steps are recommended in response to an outbreak:

  • Veterinary assessment: Contact a veterinarian immediately if you suspect strangles. A veterinarian can conduct tests to confirm the diagnosis and recommend appropriate treatment.
  • Quarantine: Isolate-affected horses and any others showing symptoms. Limit movement in and out of the quarantine area.
  • Treatment: Treatment for strangles typically involves supportive care, including managing fever and pain. In some cases, antibiotics may be used, but they are not always recommended, as they can prolong the shedding of bacteria.
  • Communication: Inform other horse owners in the area and any facilities you may have visited recently about the outbreak. Transparency can help prevent further spread and encourage others to take precautionary measures.


The recent cases of strangles in Michigan are a stark reminder of the importance of vigilance and proactive disease management in the equine community. While strangles can be a serious and potentially life-threatening disease, early detection, containment, and preventative measures can significantly reduce its impact.

Horse owners and caretakers must remain informed about strangles, their symptoms, and the best practices for preventing their spread. By working together and following proper biosecurity protocols, the equine community can minimize the risks associated with this highly contagious disease.

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