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WHAT IS THE 5-PANEL TEST: Since the introduction of DNA testing - and as more information becomes easily available through the Internet - horse folks and breeders
are better able to make responsible decisions concerning equine genetic disorders. They potentially exist in every breed of horse, but since it is Quarter Horses we
raise here, we are focused on them in particular.
The five genetic disorders that are tested for in Quarter Horses are: HYPP, HERDA, GBED, MH and PSSM1. Some of these disorders have been traced back to a
particular Stallion. For example, HYPP first showed up in the offspring of Impressive, an extremely prolific sire popular among the Halter Horse crowd for his size and
exceptionally heavy muscling. HERDA has led back to Poco Bueno, and PSSM1 is suspected to have started with King P234, although other sires are rumoured to be
involved also. An excellent article on Genetic Disorders in Quarter Horses and Related Breeds, written by Heather Smith Thomas in 2009, can be found here:
It should be emphasized that having one of these sires in a horse’s pedigree does not automatically mean the animal carries a disorder. Because they are passed
genetically (and are often a Recessive trait), these disorders follow the same rules for Mendel’s Law as colour genes do (see Basic Genetics). Passing generations have
bred out the faulty gene in many cases and, nowadays, informed breeders are eliminating them further through selective and responsible breeding. The key words
here being ‘informed’ and ‘responsible’... and that is what the ‘5-Panel Test’ is for.
WHERE TO GET THE 5-PANEL TEST: The ‘5-Panel Test’ as it has been dubbed, has been available since 2007 and is conducted by the Veterinary Genetics Laboratory
(VGL) at University of Davis (UC Davis) in California, USA. The test kit can be ordered through AQHA by the breeder/horse owner and the hair sample is sent directly
to UC Davis, with an enclosed ‘postcard’ also going to AQHA to notify them that the sample has been submitted. The results are sent directly to AQHA who, in turn,
notifies the breeder/owner and records the results on the horse’s permanent record at AQHA. It should be noted that individual tests (and colour tests) can be
ordered and submitted directly through VGL and other genetics laboratories, but to do the complete 5-Panel at one time, the kit must be ordered through AQHA.
Update: Animal Genetics (www.animalgenetics.com) has recently announced that they are now offering the complete 5-Panel test. This promises to provide much
faster results, directly to you, as compared to ordering the kit through AQHA.
HOW TO DO THE 5-PANEL TEST: The ‘sample’ consists of a small lock of hair pulled from mane or tail of the horse, which is taped to the form at the place indicated on
the sheet. It is important that the hair follicles (ends) still be attached, since this is where the DNA sampling is done. The easiest way to pull the required hair is to
wrap 20-30 strands of the mane around your forefinger as close as you can to the neck, then jerk sharply down. It doesn’t hurt the horse, most don’t pay any
attention at all. Hold the hair ends up to the light and you should see very small white ends, usually slightly wider than the hair itself. Voila! these are hair follicles
(some hair ends look dark with a tiny ‘hook’ at the end instead). Foals should have the sample pulled from the upper part of the tail, because the baby hair in their
mane is too fine.
To send the sample in, tape the hair onto the form where indicated, fold where indicated, and put this in an envelope addressed to VGL. There should also be an
Import Permit enclosed and a Declaration to fill out and sign. These should go into a separate envelope, write “IMPORT PERMIT” instead of an address and then tape
the two envelopes back to back, with tape along the two narrow sides. This allows the Border authorities to remove the Permit without disturbing your sample. If no
Permit/Declaration is enclosed in your kit, a PDF copy can be downloaded at no cost from the VGL website (www.vgl.com)
5-PANEL TEST RESULTS: If a horse comes back with a positive indication (marker) for one of these disorders, it does not necessarily mean that the horse itself HAS this
disorder. HERDA and GBED are both Recessive genes; therefore horses carrying only ONE gene are NOT affected; and their offspring would require TWO markers - one
from the sire and one from the dam - for the foal to be affected. This makes it crucial to ensure that a broodmare with a genetic ‘marker’ is never bred to a stallion
that carries the same marker.
Other disorders (MH and HYPP) are Dominant and therefore require only one gene for the horse to be considered affected by the disorder. Symptoms may vary in
intensity from non-symptomatic to acute.
PSSM1 is a little more complicated. This mutation was originally considered dominant, but is now listed as Semi-Dominant in recognition that there seems to be other
conditions at work that may act as a ‘trigger’ to cause some horses to become symptomatic at varying ages, while others remain symptom-free all their lives. As
research progresses, PSSM2, 3 and possibly 4 have been theorized, each with their own markers.
When we first started our breeding program, we decided that if we wanted to call ourselves ‘responsible breeders’, we had to look at every aspect of our breeding
stock, from bloodlines and conformation to eye appeal, to ensure we were producing the best examples of the breed that we could. It is our belief that good
conformation and disposition is key... rare colour is grand... and 5-Panel testing to avoid producing offspring with genetic disorders is essential.