Strangles

Strangles (equine distemper) is a contagious upper respiratory tract infection of horses and other equines caused by a gram-positive bacterium, equi. As a result the lymph nodes swell, compressing the pharynx, larynx and trachea and can cause airway obstruction leading to death, hence the name Strangles. Strangles is enzootic in domesticated horses worldwide. The contagious nature of the infection has at times led to limitations on sporting events.

The disease is spread by an infected horse when nasal discharge or pus from the draining lymph nodes contaminate pastures, feed troughs, brushes, bedding, tack etc.

Equines of any age may contract the disease, although younger and elderly equines are more susceptible. Young equines may lack immunity to the disease because they have not had prior exposure. Geriatric equines may have a weaker immune system.

A horse with strangles will typically develop abscesses in the lymph nodes of the head and neck causing coughing fits and difficulty swallowing. Clinical signs include fever up to 106 °F and yellow coloured nasal discharge from both the nose and eyes.

Abscesses may form in other areas of the body, such as the abdomen, lungs and brain. This is considered a chronic form of strangles called "bastard strangles" and can have serious implications if the abscesses rupture. Horses develop this form of strangles when their immune systems are compromised or if the bacteria rapidly invades the body.

Strangles has a 8.1% mortality rate. Mortality is lower in cases without complications than it is in cases of bastard strangles. The disease is very contagious and morbidity is high. Precautions to limit the spread of the illness are necessary and those affected are normally isolated. An isolation period of 4–6 weeks is usually necessary to ensure that the disease is not still incubating before ending the quarantine.

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