The most common systems of strangles are:
- High fever
- Loss of appetite
- Depression
- Inflammation or swelling of the lymph nodes around the throat
- Persistent coughing
- If left untreated, the lymph nodes can burst and cause a thick yellow to green mucus to drain from the nasal, usually from both nostrils.
Strangles is contagious, and the disease becomes highly contagious when the lymph nodes burst. The shedding of this disease can last for up to 6 weeks and is present in the saliva and nostrils. It is important to isolate a horse with strangles for up to 6 weeks to prevent other animal from contracting this highly contagious and deadly disease.