Conserving Genetic Diversity among Square Horses

I been appalled to learn how much genetic diversity among Square Horses has been irrevocably lost due to short-sighted breeding and management practices, especially here in the USA. The Bureau of Land Management has been gelding free roaming stallions for decades. Now the policy is turning towards surgically sterilizing free- roaming mares through a truly gruesome procedure with a high rate of shock, infection and death as an incision is made in the wall of the vagina in order to insert an instrument into her abdomen and destroy her ovaries.

There are currently about 50,000 wild horses and burros being held in off-range facilities. Less than .01% of the horses in holding corrals are offered on the BLM adoption site at any given time. And BLM side views are not the best means of judging a horse’s conformation and ancestry.

BUT several Bureau of Land Management Horse Management Areas have horses that have been confirmed through DNA testing to carry significant Colonial Spanish Barb Mustang etc genetic markers. That means that perhaps 5% of the horses being held by the BLM are Square or Rectangular individuals.

Although these horses are the minority of free-roaming individuals in the BLM holding pens, their number is significant when faced with the desperate need to maintain a healthy genetic diversity. Mares should make up about half of that 5%. That means that there could be approximately 1250 Square and Rectangular mares languishing in BLM holding pens. According to the Online Corral:

You can get your BLM mustang tested and see what the probability of of their carrying Iberian and/or Barb genetic markers. According to the Texas A&M horse ancestry page:

Adopters or purchasers can assume that all mares and fillies of any age have been bred while on the range and are likely pregnant.  Any heavily pregnant mares or mare that foals will not be available for pickup until the foal is at least three months old.  The foal would be offered for adoption to the mare’s adopter first.  If adopted as a pair, the foal is also eligible for the Adoption Incentive Program with an adoption fee of $25.  Delta will coordinate all appointments and additional adoption paperwork for any foals born prior to pick up...After picking up, any foals born to a wild horse are not considered wild horses under the Wild Free-Roaming Horses and Burros Act, these foals are the property of the adopter of the mare. ‘

The modern horse was re-introduced to the Americas by Spanish explorers. The earliest horses to reach North America were of Spanish origin. Although horses from other parts of Europe were subsequently introduced, some New World populations maintain characteristics ascribed to their Spanish heritage...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.

Learning about the history of the area your BLM horse comes from can help interpret the breeds the A&M computer program throws up as possible ancestral lines. Learning about the history of the breeds the A&M computer program throws up as possible ancestral lines can help clarify why they might be related to your horse. In general horses showing Thoroughbred and draft ancestral lines are reflecting post 1880 government policies. Army remount programs required that rangers run registered stallions to ‘improve’ their horses while the Bureau of Indian Affairs policy required either slaughtering or castrating Indian stallions and replacing them with draft stallions in order to eliminate the war-ponies that made the Horse Tribes such a threat to Anglo-Saxon colonizers.

The American Indian Horse Registry has five categories of registration. Their O, A and AA categories include horses of Colonial Spanish Barb Mustang type. Horses of the O category usually share bloodlines with the established Registries and may be dual registered. Horses in the A and AA category maybe descended from the remaining wild and free-roaming horse populations. The Horse of the Americas also states that Colonial Spanish type horses from the wild may be registered by inspection.

The one objective criteria for Colonial Spanish type that is consistent across continents and centuries and that breeds true, regardless of the name of the breed or registry is based on these horses’ unique bio-mechanics. The normal angle of the shoulder ( and hip) joint of the modern horse is currently recognized as an open or obtuse angle of 100-120o. Horses descended form the same stock stock as the prized Square and Rectangular horses of Baroque times show a 90o or right angle at the hip and shoulder. Since there are so few of these horses registered, every single Square Horse added to the gene pool is a treasure that can help insure the health of future generations.

The BLM Online Corral usually has at least few mares ‘born in facility’ online that might be worth a second look even when their gallery is showing horses from areas with minimal Iberian and Barb influence.So please share the link to possibly Square and Rectangular mares that are available through the BLM Wild Horse Adoption program with those who will take action.

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