Horses may stand with legs wide apart. Sweating may be evident especially between rear legs, and stumbling in the rear legs may be noted when horses are turned. Sometimes swelling is present in the lower neck area, near the thoracic inlet. They may exhibit a jugular pulse and a rapid heart rate. Changes in electrocardiogram include increased heart rate, ST elevation, and variable QRS complexes, and ventricular premature beats.
Cardiac arrhythmias are often present.
The hair becomes rough. Muscular tremors may not be noticeable, but complete lack of muscular coordination and stupor precede death.