Hyperkalemic Periodic Paralysis Disease (HYPP) is a muscular disease that affects both horses and humans. In horses, HYPP has been traced back to one horse named Impressive and has the alternative name, Impressive Syndrome, named after this horse. Symptoms of HYPP may include muscle twitching, unpredictable paralysis attacks which can lead to sudden death, and respiratory noises. Severity of attacks varies from unnoticeable to collapse or sudden death. The cause of death is usually respiratory failure and/or cardiac arrest. The HYPP gene is dominant so both homozygous positive (HH) and heterozygous (nH) will cause this muscular disorder. Only homozygous negative (nn) has no HYPP effect. Since HYPP is dominant, the effects of it can also be transposed to other species of horses when intermixing occurs. This makes the recognition and elimination of this disorder very important in preserving the inherited health of all horses.

This chart lists the probability of having inherited HYPP

nn - Homozygous negative - has no HYPP effect
nH - Heterozygous - positive for one copy of the HYPP gene
HH - Homozygous positive - positive for two copies of the HYPP gene

HYPP Testing

Animal Genetics offers DNA testing for HYPP.

Cost

$30.00 US per sample.

Sample Collection

Collect sample by pulling (not cutting) 20-30 mane or tail hairs with roots attached. It is important that you pull the hairs and confirm that the actual root of the hair is being collected. The root contains the genetic material of your horse that is needed for DNA testing. Therefore, cut hairs do not provide an adequate sample of your horse. Place the collected hairs of each horse in a separate zip-lock bag labeling the bags accordingly with the horses name or identification number. Download and complete a submission form for each sample and send along with payment to Animal Genetics for testing.

Results

Results are given using the following symbolic notation: