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 ‘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 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.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: http://www.onlinedigitalpubs.com/publication/?i=18672&page=1&p=357It 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 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.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, put “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) 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. Most of these disorders require TWO markers - one from the sire and one from the dam - for the disorder to be inherited. Therefore it is crucial to ensure that a broodmare with a genetic ‘marker’ is never bred to a stallion that carries the same marker.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. Good conformation and disposition were key... rare colour was grand... and 5-Panel testing to avoid producing offspring with genetic disorders was essential.
Understanding the 5-Panel Test
Note: In Spring of 2013 the American Quarter Horse Association (AQHA) past new regulations that require all stallions exposed to 25 or more mares during the 2014 breeding season to have a genetic disease panel test on file with AQHA prior to the registration of their foals resulting from breedings occurring after January 1, 2014. Additionally, the Stud Book and Registration Committee recommended that ALL stallions will be required to have a genetic disease panel test on file with AQHA prior to the registration of their foals resulting from breedings occurring after January 1, 2015. These new rules are denoted as Rule REG108.4 and REG108.5 in the 2014 AQHA Official Handbook of Rules and Regulations.