Heavy cannon bones are detrimental to Connemara movement, science shows

The purpose of breed associations is to facilitate the work of breeders, rather than impede it, the Canadian Veterinary Medical Association said in an article I looked at in my last posting.

So, I assumed that the breed standards set by the American Connemara Pony Society, which mirror Irish standards, were set to facilitate the movement of Connemaras.

I went looking for evidence particularly that heavy cannon bones would improve the performance of the Connemara.

Connemara inspectors use cannon size to weed out the horses that they believe are too refined — horses that reflect the breed’s thoroughbred and Arabian genes. Wouldn’t want anyone to know those are there. It’s ironic because experts on breed genetics uniformly say breeding to outside genes is exactly what animals need to stay healthy, and these experts are appalled at breed standards that limit the genetic pool and require animals to look like some arbitrary standard.

A horse with cannon bones that didn’t meet the ACPS inspection standard was failed at an inspection, which is what alerted me to the fact that this eugenics movement discriminating against refined horses was well under way with a mission to weed out any horse that was too pretty and make sure those genes didn’t survive.

What I found in my research appears to say the opposite of what the breed standards are promoting. The research indicates that heavy cannon bones greatly impede the horse. The paragraph that caught my attention was this: “Because it is costly in energy for an animal to maintain and transport itself, nature tends to limit the amount of each tissue and the size of each part to that which is equally needed.”

So, intentionally making horses carry around heavy cannon bones is the opposite of what nature intended.

The article I’m quoting was published in 1987 and is titled “The Mechanics of Horse Legs,” by Milton Hildebrand, professor emeritus of zoology at the University of California at Davis. It looks at how the structure of the legs affects everything else related to the horse.

It starts by talking about horse speed. Horses can run nearly 70 kilometers, or 43 miles, per hour, twice as fast as humans. For horses to attain great speeds and maintain them with stamina, they must have long legs that oscillate quickly, and the legs must be light but able to deliver huge thrust and withstand huge loads with economy to be able to sustain the movement, according to Hildebrand.

A racehorse completes about 2 1/2 strides per second. The stride of a racehorse can be 6.4 to 7.5 meters, or 21 to 25 feet.

Speed is the product of rate and length of stride. Rate of stride increases as the horse gets going, but length of stride takes the horse to the fastest speeds.

Long legs help lengthen the stride, but simply making a bigger horse would be counterproductive because the legs would carry too much of a load. The author notes that horse legs are longer to body size than comparatively fast animals, including the cheetah, but appear to be the optimum length, for anything longer would lead to more interference than the horse already faces.

He says that the modern horse has developed long legs in part by now standing on the end of one toe, comparative to a ballerina on point in the human world.

The horse lengthens its stride by remaining suspended in air for some of its faster gates. For example, at the gallop, it’s off the ground 20 to 30 percent of the stride.

Again, “because it is costly in energy for an animal to maintain and transport itself, nature tends to limit the amount of each tissue and the size of each part to that which is equally needed,” Hildebrand says.

He goes on to say that the most costly materials are those that have high metabolic rates, such as leg muscles; those that are heavy, such as leg bones; or those that change velocity quickly, such as oscillating legs.

He says: “Clearly, horses legs should be designed (and are designed) to be as light as possible and to distribute their weight in an economical manner.”

He notes that the “light as possible” structure does allow for emergencies. So, a horse’s cannon bone is three or four times stronger than what is needed for a gallop and two or three times stronger than what is needed for a jump. He also notes that the lower leg sometimes fails.

He discusses how a horse’s legs are built for maximum efficiency: They are designed to swing front to back. The cannon bones are stressed primarily with compression, which can be sustained with less bone than movement such as bending, which horses don’t do.

He says: “The effort required for an animal to run increases rapidly with its mass and thus its inertial resistance to acceleration and deceleration.” And if body size doubles without changing proportions (think of the coarse ideal that Connemara inspectors are striving for), the strength of the muscles and tendons increases four times, whereas the mass loading them increases eight times. So, you’re increasing the load twice as much as the strength, if I’m reading that correctly. Wouldn’t that actually make the leg more likely to fail?

He concludes: Horses must be as economical as possible in the expenditure of energy.

He talks about how horses move. To gallop, with a quarter of the time spent off the ground, horses must raise their weight off the ground each stride. Even to walk and jog, with no time off the ground, they must raise their weight four times in each cycle.

The leg recycles energy by being a pendulum, but Hildebrand notes that it’s not a normal-shaped pendulum to achieve maximum efficiency. The lower leg, which has lengthened through evolution, is lighter, consisting of “minimal bone, tendon and hoof.” The heavier part of the leg is closer to the body where it doesn’t have to oscillate as far.

This is a big sentence: “The cost of moving the leg is low if the mass is concentrated close to the pivot at hip or shoulder and high if the weight is shifted closer to the foot.”

The cost gets higher as you increase the cannon bone, which is exactly what Connemara societies are requiring of these horses. It’s backward. It’s wrong. It’s making horses that can’t move, and I’ve ridden many of them.

Someone a few years ago emailed me to say a horse she had obtained from a particularly heavy herd was impossible to get even to walk. I was familiar with the herd and emailed back: “They’re all like that.”

Who wants horses that can’t walk, much less trot and canter? How do you sell a horse like that, particularly in a down economy? Breed it, and you have two horses you can’t sell.

Hildebrand concludes that virtually all of the analysis in the article was unknown 20 years prior, or in the 1960s. But it was known in 1987, before America jumped on the bandwagon with inspections to blindly follow the Irish so American inspectors could socialize with their Irish counterparts.

Despite the science, these inspectors created ill-designed standards without considering the detrimental results that science had revealed.

They can do something about it now.

They can stop these inspections and their nonsensical type requirements, which are creating a much bigger energy requirement for horses to move.

Or, they can wait for the lawsuit that will drag even newer science into the courtroom to prove how wrong this is.

Be sure to read my own science experiment in 2024 on how a cannon bone with a bigger circumference adds extra weight to the leg.