Strangles, an ancient infectious disease primarily affecting equines, represents a significant challenge for equine veterinarians. This condition, caused by the β-hemolytic bacterium Streptococcus equi subspecies equi, a Gram-positive coccus, is often associated with outbreaks in stables and stud farms.
Understanding the nature of this disease, its clinical signs, complications, and diagnostic methods is essential to ensure the health and well-being of horses.
Strangles is a longstanding disease, widely spread worldwide. Regions with high equine density, such as Europe, North America, and Asia, are particularly affected. Although the disease can occur at any time of the year, it is often observed in winter and spring when horses are confined in closed spaces and the stress related to environmental changes (travel, equine competitions) can weaken their immune systems.
Strangles primarily affects young horses under 5 years old but can occur at any age. In a naive horse population, morbidity can approach 100%, although mortality remains generally low, at 1-5%. It takes at least 3 months to eradicate the disease in a group of individuals.
Strangles in horses is a highly contagious disease, mainly transmitted through direct contact with infected horses or asymptomatic carriers of Streptococcus equi equi. According to data collected by the French Institute for Horses and Horse Riding (IFCE), the transmission rate of strangles can be extremely high, reaching up to 100% in non-immunized horse herds.
The disease can spread particularly rapidly in stables, equestrian centers, and equine gatherings, where horses are in close contact with one another. A study conducted by veterinary epidemiologists revealed that strangles transmission can occur through multiple routes, including nasal discharge, respiratory secretions, and contaminated surfaces.
Moreover, strangles can persist in the environment for varying periods, increasing the risk of indirect transmission. According to IFCE data, Streptococcus equi equi can survive in the environment for several weeks or even months under favorable temperature and humidity conditions.
Therefore, it is essential to implement strict prevention and control measures to limit the spread of strangles. This includes isolating infected horses, quarantining new arrivals, regularly cleaning and disinfecting facilities and equipment, and systematically screening at-risk horses.
The origin of the name “strangles” in English stems from the distinctive appearance of affected horses, which exhibit respiratory difficulties and a characteristic posture with the head lowered due to inflammation of the submandibular lymph nodes.
Strangles in horses presents a variety of clinical signs, making its diagnosis sometimes challenging. Initial symptoms may not appear until 3 to 14 days following contamination. The patient can remain contagious for 1 month.
According to a study by IFCE (French Horse and Riding Institute), about 80-100% of horses with strangles exhibit fever (40°C and above), while 70-100% present swelling of the lymph nodes under the jaw, often accompanied by neck stiffness. These nodes can enlarge up to three times their normal size in severe infections. of epizootics.
Another characteristic symptom of strangles is the swelling of the lymph nodes under the jaw, known as mandibular lymph nodes. According to IFCE, these nodes can become hot, painful, and swollen, forming palpable masses under the skin. In severe cases, these nodes may abscess, leading to the formation of skin fistulas and pus discharge.
In addition to fever and lymph node swelling, horses with strangles may also exhibit respiratory symptoms. This can include a dry, persistent cough, purulent nasal discharge, and breathing difficulties, especially during physical exertion.
In severe cases of the disease, other complications can arise, such as multiple abscesses in various body parts, gastrointestinal disorders, and neurological issues. These complications can worsen the horse’s overall condition and require urgent medical intervention.
It is important to note that strangles symptoms can vary from one animal to another, and not all infected horses will necessarily show all the clinical signs described above. However, the presence of persistent fever, lymph node swelling, and respiratory symptoms in a horse should always raise suspicions of strangles and warrant a thorough veterinary consultation.
Diagnosing strangles in horses has long been a challenge for veterinarians due to the variety of clinical symptoms and limitations of traditional methods. However, with technological advancements, new, faster, and more accurate diagnostic solutions have emerged, providing practitioners with effective tools to quickly detect the infection and take appropriate measures.
Traditional methods of diagnosing strangles, such as bacterial culture and serology, have certain limitations. Bacterial culture, while considered the gold standard for diagnosing strangles, can take several days to produce results and may lack sensitivity in some cases. Additionally, serology, while it can detect the presence of antibodies against Streptococcus equi equi, does not always distinguish between active and past infections.
However, the advent of molecular diagnostic technologies has revolutionized the approach to diagnosing strangles. The PCR (Polymerase Chain Reaction) technique allows for the detection of Streptococcus equi equi DNA with high sensitivity and specificity, providing accurate diagnosis in just a few hours. Studies have shown that PCR can detect the pathogen’s presence in nasopharyngeal samples with over 95% sensitivity.
Given these challenges, it has become imperative to seek innovative and effective diagnostic solutions to combat strangles in horses.
As a company specializing in veterinary diagnostics, our rapid molecular diagnostic solution using LAMP (Loop-Mediated Isothermal Amplification) technology offers numerous advantages for equine veterinarians. This DNA isothermal amplification method enables the rapid and accurate detection of Streptococcus equi subsp. equi DNA in less than an hour.
Moreover, our solution is easy to use in the field, using samples collected from nasopharyngeal swabs or guttural pouch washes, making it a versatile method adaptable to various clinical situations. It thus offers veterinarians a new approach to diagnosing and managing strangles in equines. The benefits for daily practice in equine internal medicine include improved diagnostic responsiveness, reduced treatment delays, and enhanced management of epizootics in stables and stud farms.
Strangles remains a significant challenge for equine veterinarians, but advancements in diagnosis and disease management offer new perspectives. By combining an in-depth understanding of the disease with innovative diagnostic technologies such as LAMP, equine veterinarians can improve the health and well-being of horses while contributing to the prevention and control of epizootics.
If you’d like to find out more about respiratory diseases in horses, take a look at our webinar in collaboration with EIDS.
