Ridecamp: Re: [RC] FYI: A Theory About Equine Foot Physiology

Wow!  Thanks for sharing.  Really interesting to me - especially with a
foundered mare.  Yes, she is doing better barefoot and balance-trimmed.
Karen


On Tue, 28 May 2002 06:53:28 -0500 "Tamara Woodcock"
<plasmatica@xxxxxxxxxxx> writes:
> >From Robert Bowker, VMD, PhD, at Michigan State University College 
> of 
> Veterinary Medicine:  "A Theory About Equine Foot Physiology"
> 
> 
> >A New Theory About Equine Foot Physiology
> >
> >A Michigan State University College of Veterinary Medicine 
> researcher has
> >pieced together a new picture of equine foot physiology that 
> suggests
> >vascular systems in horse hooves function in much the same way that 
> air- or
> >gel-filled running shoes do. "Moving liquids are the best way to 
> dissipate
> >energy," said Robert Bowker, a professor in the College of 
> Veterinary
> >Medicine's Anatomy Department.  "That is why some of the major 
> running shoe
> >manufacturers market products that contain liquids in their 
> soles."
> >
> >Bowker has theorized a "hemodynamic flow" process in which he 
> proposes that
> >much of the blood in horse feet fulfills purposes other than 
> providing
> >nutrients to hoof tissues. "It dissipates energy within feet that 
> is 
> >created
> >during the act of galloping, trotting or walking," he said. This 
> theory not
> >only proposes a new physiology for horse feet, it also suggests 
> some of the
> >more widely held views in the equine industry should be revised or, 
> at
> >least, re-examined.
> >
> >For example, Bowker's theory presents a wholly different view of 
> how horse
> >feet respond to ground impact. It also suggests horses with 
> navicular
> >disease may not need to be put down and that hoof trimming 
> techniques might
> >need to be reviewed. "We may need to be trimming hooves so that 
> more of the
> >back part of the foot-including the frog--bears the initial ground 
> impact
> >forces and weight," Bowker said.
> >
> >This would encourage development of tissues that dissipate more 
> energy when
> >hooves hit the ground. "If hooves are trimmed so that the frog 
> rests on the
> >ground," Bowker said, "it stimulates the back part of the hoof to 
> grow more
> >fibrous and cartilaginous material." With digital cushions 
> constructed of
> >more resilient tissues, less ground impact energy would be 
> transmitted to
> >foot bones and ligaments, reducing internal foot problems, such as 
> 
> >navicular
> >disease.
> >
> >Currently, equine foot physiology researchers subscribe to one of 
> two
> >anatomical theories: pressure theory or depression theory. Both 
> seem to be
> >mirror images of each other. "Pressure theory says that when the 
> hoof hits
> >the ground, the pressure of the impact hits the frog of the hoof, 
> which
> >causes the back part of the foot to move outward," Bowker said. 
> Depression
> >theory suggests that when impact on the ground occurs, the pastern 
> descends
> >and depresses the digital cushion inside the hoof. "According to 
> both
> >theories, these actions push hoof cartilage to the outside, with 
> the 
> >digital
> >cushion absorbing the energy," he said. Both theories state that 
> blood is
> >pumped from the hoof at impact.
> >
> >Yet both theories share a single problem. Researchers who attempt 
> to
> >duplicate depression or pressure theory in the lab or on live 
> horses are
> >unable to do so. Problems arise when researchers attempt to account 
> for how
> >the energy of the hoof's impact with the ground is dissipated. "The 
> digital
> >cushion is made of soft, elastic tissue and acts like a spring," 
> said
> >Bowker. "So for every action, we would expect a reaction of equal 
> force."
> >Yet when researchers put energy measurement devices into digital 
> cushions,
> >that does not happen.
> >
> >"When the hoof is in the air, it registers zero pressure," he said. 
> "But
> >when it hits the ground, instead of registering positive pressure, 
> it is
> >actually negative." Bowker's hemodynamic flow hypothesis suggests 
> this
> >negative pressure is actually created by the outward movement of 
> the hoof
> >cartilage. This movement creates a vacuum action that sucks blood 
> from
> >beneath the coffin into the rear portion of the hoof. "As the blood 
> moves 
> >to
> >the rear of the hoof through microvessels in the lateral hoof 
> cartilage, it
> >dissipates the energy caused by its impact on the ground, much 
> like
> >fluid-filled running shoes do," he said.
> >
> >In developing this new theory, Bowker observed that horses with 
> good feet
> >have more blood vessels in the lateral cartilage of their hooves 
> than those
> >that had histories of foot problems. Additionally, blood vessels 
> in
> >healthier animals were located inside the lateral cartilage of the 
> hoof, 
> >and
> >the digital cushion on these animals tended to be made of 
> cartilagineous
> >material instead of elastic tissue.
> >
> >This is particularly true for horses in breeds that are said to 
> have good
> >feet, such as Arabians. "It was also true for Quarter Horses in 
> their
> >mid-20s with no history of foot problems," he said. Bowker 
> believes
> >environmental factors also contribute to the formation of these 
> kinds of
> >tissues. "We found more cartilagineous digital cushions 
> consistently,
> >regardless of breed, in domestic horses from the Rocky Mountains, 
> where
> >harder ground surfaces and higher altitudes may contribute to 
> their
> >formation," he said. In regions of the country where ground 
> surfaces are
> >softer, more horses have digital cushions made of elastic tissue. 
> "We
> >believe these horses have a greater chance
> >of having internal foot problems."
> >
> >Robert Bowker, VMD, PhD, (517) 353-4532
> 
> 
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