Arabians and Thoroughbreds: Two Types, But Related By Blood

As the Thoroughbred developed as a breed, fewer crosses were made to imported horses. By the mid-1700s, most breeding was Thoroughbred to Thoroughbred, although many of these horses, such as the famous Flying Childers, were genetically mostly or entirely Arabian blood, being the British-born descendants of imported stock.

The modern Thoroughbred has been described as about 70 per cent or more Arabian by actual blood, with the rest (30 per cent or less) from the native British horses such as mixed breed racehorses, war horses, Galloways and Hobbies. But if early pedigrees are anything close to accurate, the percentage of English blood must be much lower.

For example, The Crab Mare (probably born about 1750) was by Crab x the Partner Mare. Grandparents were Alcocks Arabian, Sister To Soreheels, Crofts Partner and Thwaites Dun Mare, so the Crab Mare was at least one-quarter Arabian. The great-grandparents are Basto, Sister One To Mixbury, Jigg, Sister One To Mixbury again, Akaster Turk and a mare from Family Number Thirty-Eight. That adds one-eighth Turk to the quarter-Arabian. In the next generation, one sees the Byerly Turk twice and Curwen Bay Barb twice, adding another one-eighth dose of Eastern blood. By the time the next two generations are included, The Crab Mare is now 25/32nds Eastern (a mix of Arabian, Turk and Barb), without including the mare from “Family Number 38”.

The next generation back adds still more Eastern blood: Young Bald Peg 100 per cent, Spanker 100 per cent and Curwens Old Spot, by the Selaby Turk out of an unknown mare, thus at least 50 per cent. Overall, a good estimate is that The Crab Mare is not simply part Arabian/Barb/Turk, but at least 30/32nds Eastern, 31/32nds if the Family Thirty-Eight was also pure Eastern! That means that this particular mare was very close to 100 per cent “Arabian” by blood, and maybe even had no English blood whatsoever.

The important thing to note is that her pedigree is very typical of the Thoroughbreds of her time. Analysis of other eighteenth- and nineteenth-century Thoroughbreds would show similar results, possibly a little less Arabian in some, but still a very large percentage. And that percentage must be the same today, since no outside blood has been added to the breed in about 200 years.

The Crab Mare was the great-granddam of the famous Pot-8-Os (registered as Potoooooooo) whose line continues to the present day through his son Waxy, grandson Whalebone and down all the way in an unbroken direct male line to stallions like Dynaformer, Rahy, Alphabet Soup, Macho Uno, Giacomo, and all of the tail-male descendants of Northern Dancer, Mr. Prospector and others.

Long after no additional Arabian crosses were made to the Thoroughbred, purebred Arabian horses continued to be registered alongside the Thoroughbred in the General Stud Book in Britain. Then in 1877, the General Stud Book added a separate section specifically for recently imported Arabians. The intent was to add new Arabian blood to strengthen the modern Thoroughbred, a concept supported in particular by Major Roger Upton, Wilfrid Scawen Blunt, Lady Anne Blunt and other Arabian breeders who believed that the Thoroughbred was, in essence, a pure but lesser-quality Arabian in which the weaker “English” blood had primarily been bred out by the late 1800s. They believed that an infusion of new Arabian blood could only improve the Thoroughbred and restore the stamina that had been lost over the previous 150 years.

There was much to support their theory that the Thoroughbred was an Arabian by blood, appearing different due only to selecting for different characteristics (primarily for speed at short distances). Certainly the Thoroughbred ancestry was nearly all Arabian, and even the appearance was similar to some desert-bred Arabian bloodlines. The only question was whether anything would be gained and what might be lost by adding fresh blood.

There were detractors who believed that the Arabian blood in Thoroughbreds was pretty much gone (despite the proof of the pedigrees) in the sense that any Arabian characteristics had been eliminated through selection for racing ability. They believed that adding Arabians to the breed at that point would have no value for further improving racing ability, but part of this was an argument to bolster the supposedly superior “Englishness” of the Thoroughbred and dismiss the “foreignness” of the Arabian.

In the end, faced by considerable opposition from Thoroughbred breeders, the Blunts and other Arabian breeders decided to focus on saving the desert Arabian bloodlines, and the Thoroughbred people continued to breed only Thoroughbred to Thoroughbred. In England, an Arab Horse Society was formed in 1918, and the last Arabians registered in the GSB were those born in 1922.

In the United States, the American Jockey Club's Stud Book also provided the first registry for Arabians in that country. The American Stud Book was created in 1873 and had a separate section for “imported Arab, Barb and Spanish (meaning Spanish-bred Arabian) Horses and Mares.” The big question is whether any of these Arabians were crossed with Thoroughbreds to produce registered Thoroughbred stock.

In the mid-1800s, Kentucky Thoroughbred breeder A. Keene Richards did exactly that. He thought the Thoroughbred could be invigorated by adding good Arabian blood, so he went to Arabia and brought back the best horses he could find. He bred them to his Thoroughbreds and raced the offspring, but they lacked the necessary speed to be competitive. He tried again in 1855, taking longer in his selection of really top quality Arabians and tried the breeding experiment again, but the resulting foals were still too slow to compete with Thoroughbreds, even when given a considerable weight advantage. As a result, his experiment was discontinued, so presumably there are no registered descendants from the Richards' Arabian-to-Thoroughbred breedings.

Eventually, the Arabian breeders began their own registry in the United States, and some Arabians were registered in both. The new Arabian registry was created partly due to the Jockey Club refusing to recognize the pedigrees of newly imported Arabians that were not descended from horses already registered in the GSB in Britain or with the Jockey Club. This excluded all new imports from elsewhere, because the Jockey Club could not be bothered to verify the foreign pedigrees. Some breeders continued to double-register those Arabians that still qualified for Jockey Club papers, but the last purebred Arabians registered with the Jockey Club were foals born in 1943.

Today, only Thoroughbreds are registered in the Jockey Club Stud Book and Britain's General Stud Book. But in truth, they are still “Arabian” under the skin.

Here are some books that provide more information about Arabian and Thoroughbred horses.