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Horse Ancestry

Genotyping and Breed Testing

Ancestry testing is $40 per animal. Sample submission form.

The modern horse was re-introduced to the Americas by Spanish explores. The earliest horses to reach North America were of Spanish origin. Although horses from other parts of the Europe were subsequently introduced, some New World populations maintain characteristics ascribed to their Spanish heritage. There are more than 58 million horses in the world, with more than 10 million horses in the United States of America (FAO 2013 data). It is difficult to calculate exactly how many horse breeds there are as the Domestic Animal Diversity System lists 1549 horse breeds, however many countries list same breeds like Arabian, Thoroughbred and etc. so that some breeds are counted more than one time. The Department of Animal Sciences – Oklahoma State University maintains a website that lists over 200 breeds alphabetically, International Encyclopedia of Horse Breeds by Hendricks (1995; 2007) describes nearly 400 breeds but estimates there are well over 600.

Throughout the years we collected and genotyped an extensive number of horse breeds and populations from around the world (see selected publications), however to represent our reference panel for ancestry testing we selected 50 breeds that are most common for the North America and also represent the major horse groups: draft horses; ponies; Oriental and Arabian breeds; Old World and New world Iberian breeds. Selected breeds are more probable to be the ancestors of current horses in North America and it would be unreasonable for us to use rare or endangered breeds like Waler (Australia), Timor pony (Timor Island), Cheju horse (a southern island of Korea), Namib horse (Africa), Tushuri horse (Georgia) or Pindos (Greece) and etc. Also some North American breeds are not on the list, - example: Appaloosa, American Paint horse, because registries are open or partially open and allow crossbreeding. Mustangs are also not on the breed list as it is now primarily a feral horse found in the western United States and managed by Bureau of Land Management (BLM). Originally mustangs were Spanish horses or their descendants, however throughout the years they had influence from many different horse breeds. There are several mustang registries, but overall there is just too much complexity to consider them in breed ancestry analysis.

Horse ancestry testing at Texas A&M University is based upon comparing the DNA genotype of the subject horse to a reference panel of 50 horse breeds.  Using a computer program based upon maximum likelihood analysis, the variants present at each genetic marker system tested for the subject horse are compared to those for each reference breed.  For each breed comparison the probability that the subject horse came from that breed is calculated based upon the product of all the systems genotype probabilities.  We then report the three breeds with the highest probability that the subject horse could have come from the breed in order of their probability of being an ancestral breed.  The results cannot give the proportion (percent) of the breed that the subject horse may have.  That really isn’t possible because horses are so genetically similar.  The test is reasonably good but there is no way to determine how accurate it is.  If a purebred horse is tested it will almost always be assigned to the correct breed.  When a two breed cross is examined, the two parental breeds will almost certainly be given very high probabilities although not necessarily the 1st and 2nd assignments.  The more breeds involved in a cross the lower the probability that a good result will be delivered.  Also, understand that even though three breeds are reported that does not mean the subject horse has all three in its ancestry.  Another point is that breeds within a group of related breeds will be given similar probabilities. Thus, the subject horse may be half Belgian draft and half Suffolk but the test results may show Percheron or even a pony breed. That is because these draft breeds are very similar at the level we can test and the true pony breeds are closely related to the heavy draft breeds.  As well, many breeds have Thoroughbred in their make-up and they will give similar results and will often show similarity to Warmblood breeds.

Philogenetic tree of 50 selected breeds showing their relationship:

You can download the phylogenetic tree pdf.


Our laboratory is an Institutional member of the International Society for Animal Genetics (ISAG). We participate in ISAG comparison tests and report DNA types according to standardized nomenclature. Our most recent certificate of participation. ISAG institutional member number 105247.

You will receive two reports. Horse genotyping report - DNA type (aka DNA profile, aka DNA fingerprint). DNA type shows the markers used (microsatellites – VHL20; HTG10 and etc.) with allele sizes for the markers coded in letters (VHL20 – PR; HTG10 – LR; AHT5 – KN and etc.). DNA types are reported according to standardized nomenclature of ISAG. If one of the parents or both parents are available, parentage verification will be performed and it will reflect on the report (sire/dam qualification/exclusion). Second report is the horse ancestry report with breed assignments. We do not provide percentages (please see description above). Ancestral Equine Report Example.

More information

More information on the particular breed or region could be found under our research and publications page.