• VOLUME 40 • © HORSES For LIFE™ Magazine • Horses For LIFE Publications •

Cook: "The added weight of a rider is akin to the added weight of pregnancy: It is something that evolution has anticipated."

When I came across the phrase above in an unrelated article by Dr. Cook, it created a resonance on a subject of a recent article by Stormy May questioning the capillary pressure exerted by saddles on the horse’s back.

The following is from Volume 38 from our October 2008 Edition
http://horsesforlife.com/TruthInTheBack

“...pressure-sensing technologies led to a flurry of interesting scientific studies in the equine world. When this information was combined with other studies of mammalian muscle tissue, it all suddenly pointed to a huge dilemma. In the Journal of Veterinary Science Volume 14 No. 11, 1994, well known veterinarian and saddle fit expert Dr. Joyce Harman reported the results of a study using the Saddletech pad. She wrote:

"For the purposes of this study, saddles with pressures of up to 1.93 psi were graded an excellent fit, between 2.0 and 3.38 psi without persistent pressure points were graded fair, and saddles that exceeded 3.4 psi or had persistent pressure points throughout the session were graded poor. These numbers were derived from preliminary data indicating that it was difficult to find an English saddle with pressures below 0.75 psi, which is the highest pressure found in the capillary bed. Pressures that exceed 0.75 psi will close down the blood flow in the arterial capillary bed."

So what does it mean if the blood flow is shut down? This is what happens on a small scale when we press on our skin and it turns white, or if we sit in an awkward position for a longer amount of time, and we experience our leg or arm "going to sleep". The author Mary Wanless writes in her book "For the Good of the Horse", "Perhaps one of the horse's saving graces is that squeezing the blood out of his tissues causes pain for the first ten to fifteen minutes of a ride, and then his back goes numb."

So until we learn how to levitate saddles, even a saddle with an excellent fit, the best air/foam/wool stuffed panels and an average weight rider, will have pressures which are more than twice what it takes to shut down the blood flow within the muscles. Dr. Harman goes on to state that in studies of canine and human muscles, sustained pressure of only 0.68 psi for over two hours causes significant tissue damage.

It is important to note that the Saddletech sensor pad used in these first studies used sensors developed to evaluate the risks of pressure sores in bedridden humans, and only measured pressures of up to 4 psi. More modern sensor pads, such as the FSA (Force Sensing Array) system developed by Vision Engineering Research Group (VERG Inc.) of Winnipeg, Manitoba, Canada can record much higher pressures. In one test involving Western saddles with high priced pads, average peak pressures measured between 8.25 and 14 psi. (Wesley, E.D.; McCullough, E.; Eckels, S.; Davis, E.; Article #9329; 2007; "The Horse" magazine).

Pressure-sensing pads also have the limitation of only recording pressures at the level of the skin. Saddle pressure is transferred through the muscles to the bony structures underneath (the vertebrae and ribs) and if we could measure the pressure there, it would be significantly greater. Dr. Harman writes that, "There is surgical evidence in human medicine that subcutaneous necrosis [the death of cells] begins closer to the bone before cutaneous redness and ulceration is seen." This means that if we've been around horses long enough to notice white spots or tender swellings in the saddle area, we are only witnessing the end results of a long process of tissue destruction.”

I have to say that this article gave me as a rider and trainer great pause and disturbed me at a very fundamental level. It made me question whether I had been inadvertently hurting my horses, if I should be getting on their backs. I am not a short person and my weight has been known to fluctuate through the years ( a polite way of saying there are times my weight has not been what I would have liked), including three cases of pregnancy. Did I have any business being on the back of the horse at anytime?

Then we started receiving letters from our readers asking exactly the same question. How valid were these studies, were we hurting our horses by riding them for longer than 10 to 15 minutes? This is one of the concerns of Alexander Nevzorov, why he advises to limit the length of time we spend on the horse’s back. Well aware of the research, he has decided to take a proactive approach and insist that those that participate in his school recognize the possible danger to the horse’s back. His passion fueled by his extensive study of the horse.

Then I came across the statement by Dr. Cook. He wasn’t talking about the back, but what he said sent me looking. Something I hadn’t thought about.

“The added weight of a rider is akin to the added weight of pregnancy: It is something that evolution has anticipated.“

It sent me on a quest to discover what kind of weight does the mare carry. What kind of continuous pressures had evolution expected the mare’s back and skeleton to carry 24 hours a day?