Hyperkalemic Periodic Paralysis

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Hyperkalemic Periodic Paralysis

• By Tammy Bragg

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What is HYPP?

• Hyperkalemic periodic paralysis (HYPP) is an
  inherited disease that leads to uncontrolled
  muscle twitching or profound muscle weakness, and
  in severe cases, may lead to collapse and/or
  death.

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Heredity

• All horses affected trace back to one stallion
  Impressive (AQHA)
• Can be tested for using DNA
• Horses whose ancestry include Impressive have
  three possible DNA results when tested

N/N
N/H
H/H
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Impressive

• Quarter Horse stallion born in 1969, died in 1995

• Was undefeated at halter and was the first
• AQHA World Champion Stallion

• Sired 2,250 horses

• Daughters have produced numerous point
• earners and champions

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Impressive

• Most of his offspring were
• shown in halter due to
• heavily muscled appearance
• (may be linked to HYPP
• occurrence)

• Today, HYPP affects more than 55,000
  descendants
• in three breeds (Quarter Horse, Paint,
  Appaloosa)

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Symptoms of N/H Horses
Common
Less Common
Increased respiratory rate
Muscle spasm
Sweating
Recombency
Continuous muscle fasciculations
Arrhythmia
Weakness
Death
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Symptoms of H/H Horses

• Increased respiratory rate
• Involuntary recombancy (dog-sitting)
• Prolapse of third eyelid
• Continuous muscle fasciculation
• Weakness
• Sweating
• Cyanosis
• Drooling
• Death

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Treatment

• Maintenance
• Dietary Management (low potassium levels)
• Limit stall confinement
• Acute episodes
• IV carbon gluconate
• 5 bicarbonate solution
• Dilute plasma with saline
• Walking

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New AQHA Regulations

• Starting with the 1998 foal crop, the AQHA now
  prints the following on the registration papers
  of any horse which is a descendant of Impressive
• This horse has an ancestor known to carry HYPP,
  designated under AQHA rules as a genetic defect,
  AQHA recommends testing to confirm presence or
  absence of this gene.

Only a horse whose sire and dam have tested
N/N will not have this statement on their papers.
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Other Breed Associations

• As of today, no other American breed association
  has any regulations regarding HYPP.
• ApHC of Canada has EXTREME rules
• Must be gelded or spayed to be registered, 2000
• Denied registry or identification as of 2002

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Impact on Horse Industry

• New proposed rules to eradicate HYPP
• AQHA beginning in 2007, only horses testing N/N
  will be eligible for use as breeding stock may
  not even be able to register N/H or H/H horses
• Many believe this will cause a decline possibly
  the best line of halter horses. However, there
  are many individuals who are of this bloodline
  and who are N/N

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References

• www.aqha.org
• http//www.equisearch.com/care/illness/equineneuro
  logical/links/
• http//www.vgl.ucdavis.edu/lvmillon/hypp/hypp_fac
  ts.html