Strangles

Streptococcus equi

Shetland pony with strangles

Shetland pony with strangles (side view)

Strangles is a highly contagious and serious infection in horses and other equids, such as donkeys and mules, caused by the bacterium Streptococcus equi subspecies equi (S. equi). The disease is characterized by severe inflammation of the upper respiratory tract, with swelling and often abscess formation in the lymph nodes of the head and neck. Strangles is a significant concern in the equine industry due to its high infectivity, the potential for outbreak situations, and the economic losses it can cause.

Symptoms and Diagnosis

The clinical signs of strangles can vary but typically include fever, nasal discharge, swollen lymph nodes (which may abscess), difficulty swallowing, and breathing difficulties due to the swollen lymph nodes compressing the airway. Stridor, or noisy breathing, and cough are also common. The disease is named "strangles" because the swollen lymph nodes can sometimes strangle the airway, leading to severe breathing difficulties.

Diagnosis of strangles is primarily based on clinical signs and can be confirmed through bacteriological culture of nasal swabs or pus from abscesses, and more recently, by PCR (Polymerase Chain Reaction) tests which detect the DNA of the S. equi bacterium.

Transmission

Strangles is highly contagious and is transmitted through direct contact with infected animals or indirectly through contact with contaminated water, feed, equipment, or handlers. The bacterium can survive for several weeks in the environment under favorable conditions, contributing to the spread of the disease.

Prevention and Control

Prevention of strangles involves biosecurity measures such as quarantine of new or returning horses for at least two weeks, good hygiene practices, and vaccination. Vaccines against strangles are available and can reduce the incidence and severity of the disease but may not prevent it entirely. During an outbreak, strict quarantine and disinfection measures are essential to control the spread of the disease.

Treatment

Treatment of strangles focuses on supportive care to relieve symptoms and prevent complications. Antibiotics may be used in certain cases, especially to prevent secondary infections, but their use is somewhat controversial as they can interfere with the development of immunity and the natural course of the disease. Abscesses may need to be lanced and drained by a veterinarian.

Complications

Complications from strangles can include "bastard strangles," where abscesses form in other parts of the body, and purpura hemorrhagica, a severe immune-mediated condition that can be fatal. Horses that recover from strangles can become carriers of the bacterium, harboring it in their guttural pouches and posing a risk of infection to other horses.

Conclusion

Strangles is a serious disease that poses a significant threat to equine health and requires diligent management and biosecurity measures to prevent its spread. Early detection, isolation of affected animals, and appropriate treatment are crucial in managing outbreaks and minimizing the impact of the disease.

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