HyPPflyer

Hyperkalemic Periodic Paralysis is a disease that affects the sodium ion channels of an af-flicted horse. The horse's muscle cells flood with sodium, and potassium leaks out, which causes the muscles to become hyperactive and can cause seizure-like episodes that can last anywhere from a few minutes to several hours. The symptoms of the disease range from mild to severe and may include: mild muscle twitching anywhere on the body and neck, excessive yawning, eyes rolling back in the head, mild to severely crawling skin from the rear flank area through the neck area, profuse sweating, paralysis of the front or hind quarters, paralysis of the windpipe which may cause the horse's breathing to sound raspy, and paralysis of the muscles surrounding the lungs or heart, causing death due to suffocation or heart attack. Stressful situations and general anesthesia can cause positive horses to have and HYPP episode. Some horses seem to do well with no special care, while others seem to have ep-isodes in spite of low potassium diets and medication. Some may not show symptoms for several years and others may die from their first and only episode. HYPP symtoms can appear at anytime through the course of the horse's life, from the time it is born to it's late teens.

A test was made availabe to the public in 1992. Breeders were encouraged to use this test to choose breeding stock who did not carry this disease. By doing so, they could pass on all the wonderful traits Impressive had to offer and eliminate the disease. Some breeders found the disease had a useful side-effect. The constant electrical firing in the muscles increased the muscle definition with less exercise and made these horses easier to "fit" for halter with less work. Many chose to use the test to breed for the disease instead of away from it. HYPP is designated by research centers and by the AQHA to be a dominant genetic disease. It requires only one parent to have it to breed it forward. It does not skip generations and cannot be bred out by crossing to another breed. The ONLY way to stop the disease is to test for it and not breed horses who carry it.

There are 3 test statuses for HYPP. N/N means the horse carries 2 normal genes, it does not have the disease, nor can it pass it on. These are the horses that are recommended for use as breeding stock. N/H means the horse carries 1 normal gene and one HYPP gene (known as heterozygous for HYPP) and will statistically pass the HYPP gene to 50% of it's offspring. H/H means a horse carries a double copy of the gene (known as homozygous) and will statistically pass 1 copy to 75% of it's get and a double copy to 25%. H/H guarantees 100% of it's get will have the disease. N/H and H/H horses should NOT be used for breeding.

Through outcrossing to other breeds, culling and selling positive horses as grade stock, and breeding positive stallions to grade mares, HYPP has been spread to a large portion of the equine industry. For this reason, testing for HYPP in grade horses as well as registered horses is important! You cannot look at a horse and know that it has this disease. Testing is the only way to be sure of the status. The disease does not affect just the horse, but the owners and handlers as well. Many people have been badly hurt by horses having attacks under saddle as well as by horses thrashing to get up when part of their body suddenly goes out from under them due to paralysis. Going down under saddle is not a common occurance, but it does happen. It is also heartbreaking for the owner who loves their horse to lose it to HYPP.

You can help eliminate HYPP by contacting the Stallion Committee of each breed registry and telling them you want to see rulings in place for mandatory testing of ALL horses with Impressive bloodlines and to offer registry to the ones who carry the disease as non-breeding animals only. You can also help through educating buyers about HYPP and encouraging them to request any animal they are looking to buy have the status available. And last, but not least, print this flyer and help spread the word.