Two shakes of a dog's tail: Gyro locomotion of animal skin

What if scientists took the same tools they use to analyze how horses walk, trot, canter and gallop and turned it to how they use their bodies?

Forget the legs and hooves (or paws).

Most mammals have a quantity of loose skin that they can move. That looseness gives the skin a locomotion all its own and now scientists are measuring it and trying to understand how and why animals are able to shake as much as 70 percent of liquid off their bodies.

It's not a linear locomotion; it's a gyro, or rotational movement around the animal's axial skeleton.

It's a good thing they can do it. If they couldn't, chances are the water would freeze, and they might get hypothermia, according to David Hu, PhD at Georgia Tech University. Or maybe the weight of the water would slow them down in their hunting--or fleeing from being hunted.

It's a shame the study doesn't include an analysis of horses shaking. I think they do more of a whole-body shudder than a rotational loose-skin shake like a dog or other mammals. Maybe it has something to do with the way they can involuntarily twitch their skin to get rid of a fly. Their shake is powerful but unique, I think.

And horses shake off dust as well as water. Shaking is all part of rolling.

This weekend, media like CNN aired segments with commentator Jeannie Moos plugging humor into the research, including an interview with Dr. Hu at Georgia Tech via Skype, who was previously featured on ABC's Good Morning America:

Read the abstract of Dr. Hu's paper. Visit the web site for Dr. Hu's lab at Georgia Tech. Before he became fascinated with shaking dogs, he researched how mosquitoes fly in the rain.

Click to go to easy ordering page; this poster can soon be hanging on your wall!

© Fran Jurga and Hoofcare Publishing; Fran Jurga's Hoof Blog is a between-issues news service for subscribers to Hoofcare and Lameness Journal. Please, no use without permission. You only need to ask. This blog may be read online at the blog page, checked via RSS feed, or received via a digest-type email (requires signup in box at top right of blog page). To subscribe to Hoofcare and Lameness (the journal), please visit the main site, www.hoofcare.com, where many educational products and media related to equine lameness and hoof science can be found. Questions or problems with this blog? Send email to blog@hoofcare.com.  

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From Sim to Mo-Cap to Slo-Mo: Have Another Look at the Horse in Motion

by Fran Jurga | 28 October 2009 | Fran Jurga's Hoof Blog

Today I hurt my eye and it made the world a different place. Depth perception was different, some things don't quite line up, and this computer screen is a little blurry so this post will be a media-rich one. I'll let the videos tell the story.

And the story is exactly what I have been experiencing: how do we look at things? You read research reports and case studies and observations on this blog all the time, but they are from the viewpoints of different original sources. Here are some examples of the sources the Hoof Blog uses.

This is a computer-generated leg model from the University of California at Davis. The model lives in a perfect world. Someone designed a limb with arbitrary (or perhaps intentional) conformation and measured the resulting tendon, ligament and muscle forces if this ideal limb was moving over a perfectly smooth, non-deforming surface.

This is what we now call "traditional" two-dimensional video analysis, often used for before-and-after shoeing and trimming evaluation.

This very brief clip is 3-D analysis. You might want to use the play button to start and stop it and see more detail.

Finally, here's high-speed video, or what you might call high-quality slow motion. This polo pony is exhibiting the same stride characteristic as the computer model at the top but wow! he is influenced by the weight and lean of his rider and the variable deformability of the field as well as, no doubt, probably some conformational traits that offset his limb alignment. This is the real world.

There are plenty of other ways to capture horses and model their movement to study and analyze them; the idea here is that when you read an article, the authors may be extrapolating data from a computer model or from subjective observation with no data collection. You have to read the fine print and always take into consideration how a study was conducted and how many horses were in a study.

Does the moving horse interest you? Cornell University will host a veritable festival of motion capture, slo-mo and gait analysis at the 26th Farriers Conference November 14-15 in Ithaca, New York at the College of Veterinary Medicine. The early registration deadline is Friday so get organized and save $50 over the on-site fees.

Speakers at Cornell include farriers Scott Lampert of OnTrack Equine in Minnesota and Mark Aikens from Anglia Equine in England, both of whom are leaders in using videography in analyzing how shoeing and trimming effect horses' movement. Dr. Jeremy Rawlinson of Cornell will demonstrate the use of Cornell's force plate system and de-mystify the concept of ground reaction forces.

Hoofcare & Lameness is thrilled to be a part of this event. For a full schedule and list of speakers, and to register online, click here or go directly to http://www.vet.cornell.edu/education/conferences/farriers/


© Fran Jurga and Hoofcare Publishing. No use without permission. You only need to ask.

Fran Jurga's Hoof Blog is a between-issues news service for subscribers to Hoofcare and Lameness Journal. This blog may be read online at the blog page, checked via RSS feed, or received via a digest-type email (requires signup in box at top right of blog page).

To subscribe to Hoofcare and Lameness (the journal), please visit the main site, www.hoofcare.com, where many educational products and media related to equine lameness and hoof science can be found.

Questions or problems with this blog? Send email to blog@hoofcare.com.