Wednesday, February 25, 2015

Frog Function?

How important is the Frog and what's it supposed to do anyway? 

Whether you are a hoof care professional or a concerned horse owner this simple question is probably one that has come up often. With over 30 years as a professional farrier, now teaching both in the states and abroad you would think that I would find that those involved in caring for the horse's hoof would have the answers to these questions and that there would be agreement in how it were treated. That's what you would think right? But for reasons that sometimes allude me that is not the case. 

The importance of the frog and its function will depend largely on your perspective and your level of understanding of hoof function. Having studied hoof/foot function for the better part of 30 years from the perspective of; what is foot function with and without the constraints of horseshoe? When I say that I have dissected thousands of frogs you may experience flash backs of your time spent in high school biology class and recall the smell of formaldehyde. That's not quite how one goes about dissecting the horse's frog. My dissections began with asking questions, simple questions based on commonly accepted theory. What are some of the commonly accepted theories you ask? 
  • The frog is a pump aiding in circulation
  • The frog aids in traction because of its unique triangular shape
  • The frog is a shock absorbed because it is softer than the hoof wall and more rubber like.
  • The frog works with the digital cushion to help in foot expansion to aid in circulation
Please take note that I qualified the question with the word "theories". Theory is simply a hypothesis or an assumption based only partially on fact. I believe that the reason we have not seen much research done on the function of the frog is because the theories on hoof function are vague and to simplistic. I have stated it hundreds of times, "The greatest problem facing today's farrier is their complacency with simplicity." 
I will admit that frog function in of itself can be simply explained, this provided you have a working knowledge of the hoof function model it relates to. If for example your foot function model is based on circulation, then the frogs primary function will likely involve aiding in circulation. If your model is based on shock absorbency, then the primary function will be shock dissipation. You get the drift. 
When I first asked the question; what is the frog's function? I was in the midst of investigating hoof function. I was never satisfied with the simplistic hoof function theories I was asked to accept. I have a tendency to challenge conventional thinking and the way I challenge it is by asking very simple questions. These questions were always based on a definition I learned while working as an assistant to Master Blacksmith Paul Spaulding of the Cooperstown Farmers Museum in upstate New York some twenty years ago. The definition is Structure + Function = Performance (S + F = P).
Armed with this definition I began to question conventional and sometimes the not so conventional hoof theories of the day. 

My line of questioning was simple. Here are a few examples of such questions:
  1. If the frog is meant to be a pump why is it shaped like a triangle, why not more like a half sphere or pad?
  2. If the frog is meant to be a pump then why does the frog spine exist, a dense shark fin like appendage that  resides below and behind the DDFT? 
  3. If the frog is meant to aid in expansion then why in the healthy foot is the frog spine denser than the surrounding frog horn? 

Applying the definition to the frog and each of the structures of the foot allowed for the development of the "Suspension Theory of Hoof Dynamics", a comprehensive foot function theory. So what is the function of the frog? In my humble opinion it is the primary vehicle for the deliver of stimulus to the caudal (back) aspect of the foot, this allowing for the correct distribution of energies to the ungular cartilages. The Frog's shape and the shape of the frog stay (V in sole) protect the coffin joint and P3 from excessive torque created at impact by allowing for the correct function of the ungular cartilages. The functions of the frog are many, but can be defined as:
  • "Support"; supporting physiological function by acting as a vehicle for the delivery of stimulus to the caudal foot (energy management).
  • "Protection"; by aiding in the distribution of energies created by the stride.

To learn more about the Suspension Theory of Hoof Dynamics and Frog function visit our website at 

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