HYPP is the defect in a gene that effects the proper function of sodium channels in the muscle. When a sodium channel is performing properly, and doing it's "job", it regulates the travel of Sodium to muscle tissue, causing the controlled contractions that lead to functional movement.
If the disease is managed correctly, it is possible to have some control of the signs and symptoms, however, in some horses it seems to be rather difficult to get the disease to a manageable level. The most common sign of HYPP is severe muscle tremors, and associated muscle weakness. After an attack, sudden death can occur. The exact reasoning is unknown, but it is thought that death is caused by paralysis of the respiratory system.
In horses with HYPP, it is important to feed the horse a diet that is low in Potassium (as Potassium can trigger attacks), being sure to allow the horse adequate room to move, as well as encouraging exercise, and to feed smaller, more frequent feedings. There are some medications that are thought to help the symptoms of HYPP (Acetazolamide or hydrochlorthiazide).
During an attack, prompt emergency veterinary care is extremely important.
If you suspect your horse may be HYPP positive, be sure to contact a licensed veterinarian immediately to get a correct diagnosis and a treatment plan.