I think it is a matter of time before the geneticists control the universe. I was watching a show on HBO where doctors were injecting some modified form of the HIV virus into brain tumors and curing people of cancer. Not simply upping their survival time. Flat out giving them a new start on life. And to think Europe is holding fast against the proliferation of genetically modified crops and the anti-vaxxers are still paranoid about measles protection.

It seems like a  matter of time before someone constructs a genetically perfect thoroughbred, capable of winning anything from five furlongs on the turf to a mile and a half on the dirt, and reproduces that runner ad infinitum, doesn’t it?

Of course until scientists figure out how to breed a crop of Secretariats, we’re stuck with the old fashioned way, breed the best to the best and hope for the best.

There was a time I thought lack of diversity in the breed was responsible for the lack of improvement in racing times over the years. There are two things I’ve come to see: the breed is more diverse than we might think, and if you really want a better horse, the answer may actually be less diversity.

Because in most western civilizations incest is criminal, most of us have developed a revulsion to the idea. The main argument against inbreeding is that it is easy to pass on bad recessive traits, but there is a solution to that – only breed genetically clean lines. Of course the most compelling argument for a genetically diverse breed is that it protects the breed from extinction in the case of a catastrophic disease. Sameness makes all vulnerable, while diversity may protect some of the species.

It is an interesting conundrum for modern breeders. Find the strongest genetic line and reproduce it over and over, or create broad diversity in the hope of finding a new, better genetic combination?

It is a myth that inbreeding (even with humans) is destined to produce seriously defective progeny. It is equally a myth that outcrossing produces animals with no genetic defects or stronger animals. The fact is that IT IS JUST AS LIKELY TO SEE A GENETIC ISSUE WITH DISTANTLY RELATED ANIMALS AS WITH CLOSELY RELATED ONES. If you are wondering if that is true, humans have been outcrossing since a few begats past Genesis and we still haven’t eradicated heart disease, cancer, Alzheimers, and an endless list of genetic fallacies.

But be careful what you wish for. A genetically perfect human (or horse) may ultimately expose an unanticipated weakness.

Let’s first clarify what the different terms mean. INBREEDING refers to a close cross between a given pair of animals. This might mean mother to son, father to daughter or brother to sister. This is a bit of a scary proposition for most breeders, especially since there are so many factors to consider beyond raw ability. I’ll point out that if you have a purebred dog, it got to look like it did through careful inbreeding. I’ll also point out how many sons and daughters of past champions win their breed at Westminster. The mistake dog  inbreeders make is breeding for only a small number of characteristics generally related to outward appearance. In doing so they have created animals with serious flaws, for example, the bulldog with his pushed in face making breathing a great chore. Having a horse that can run all day isn’t as much an advantage if the horse is psychotic and won’t go into a starting gate.

LINEBREEDING refers to mating two animals that are closely related to the same ancestor(s). For example, two horses with the same grandsire.

OUTCROSSING is the breeding of two animals that are not related within the first four or five generations. For years, outcrossing has been the preferred way of selecting breeding pairs, mainly because of the thinking that diversity was the right way to strengthen the breed.

Inbreeding and Linebreeding can bring rapid improvement to a breed, although it can also bring out genetic problems that were previously hidden for generations. Inbreeding, and to a certain extent linebreeding, provides some certainty of outcome. The mating of two horses from the same close ancestors has a strong probability of producing superior offspring. It is certainly an attractive bargain for breeders to consider.

On the other hand, a 4X5 outcross may produce anything from a champion to a horse that never makes it to the track. At the least it is difficult to predict what kind of runner you’ll wind up with.

To a degree breeders have embraced the idea of limiting the number of stallions that constitute the breeding stock. Whereas not that long ago stallions were limited to covering 35-40 mares, now the best stallions cover upwards of 200 in a season. In reality there may be only 600-800 stallions that define a crop in any respective year. Of course, it would still require 20,000 different mares to produce 20,000 foals, and that may limit the amount of inbreeding or linebreeding that can take place.

Thoroughbreds have always been required to “live cover,” meaning the stallion and mare must physically couple to produce a foal. Quarter horses (and other show breeds) have been allowed to use artificial insemination techniques for many years, and if you look at a quarter horse futurity field, it isn’t unusual to find multiple runners from the same sire.

Will thoroughbred breeding head in the same direction? It is certainly a possibility. Animal rights people often protest that breeding a stallion 300 times over three months (up to three times a day) is abusive to the animal. From that perspective, does it make sense to collect sperm all year and use artificial insemination? And if that becomes the practice, will it make sense to use even fewer stallions to produce the annual foal crop?

One of the arguments that has gained traction is to breed to produce horses that are not seriously afflicted with exercise induced pulmonary hemorrhage (EIPH), essentially obviating the need for raceday Lasix. In reality, only about 3-5% of all horses have EIPH so intensely that they would be unable to race without Lasix. It may be easy to say serious bleeders simply will not race (or subsequently breed) but if those horses are not allowed to race, their fate may often lie in a slaughterhouse. Which is the right thing to do?

As for other drugs (analgesics and anti-inflammatories) horses are athletes and injury is an inevitable part of the sport. Sure, some horses may be genetically predisposed to certain types of problems, but we will never create an animal impervious to injury. If breeding is the answer, it must only be to the question of how certain genetic conditions can be eliminated without some unintended consequence as we’ve seen with dog breeds.

In a world where breeding was tightly controlled from a central location and where the reproductive stock was tightly controlled, perhaps we could breed faster runners. Or perhaps 300 years of breeding horses from only three foundation sires (the Darley Arabian, Godolphin Barb, and Beyerley Turk) has caused the breed to reach its maximum physiological potential. Perhaps we can’t engineer a horse that can run any faster than Secretariat did in the Kentucky Derby.

Even if the advances in genetic testing and the concomitant ability to create more and more predictable runners may dominate future breeding efforts, I think perhaps we currently have found the best compromise between genetic sameness and genetic diversity, at least inasmuch as it can apply to a pure breed of blood horses. A small, but not miniscule, number of stallions being bred to a large population of mares.

I’ll leave you with this from a 2005 article in Popular Science.

Cavendish bananas consumed annually worldwide are perfect from a genetic standpoint, every single one a duplicate of every other. It doesn’t matter if it comes from Honduras or Thailand, Jamaica or the Canary Islands-each Cavendish is an identical twin to one first found in Southeast Asia, brought to a Caribbean botanic garden in the early part of the 20th century, and put into commercial production about 50 years ago. That sameness is the banana’s paradox. After 15,000 years of human cultivation, the banana is too perfect, lacking the genetic diversity that is key to species health. What can ail one banana can ail all. A fungus or bacterial disease that infects one plantation could march around the globe and destroy millions of bunches, leaving supermarket shelves empty.

Something to think about as we contemplate the future of the thoroughbred.