journey to better hooves: November 2012

Friday, November 30, 2012

Gus "swapping study"

I wanted to upload some pictures of Gus' hooves for a while now.

Gus was born and raised in Texas and for most of his first 4 years of his life lived on large pastures on ranches with horses, cattle, ponds and streams. He grew up a lot like a wild horse. He never wore shoes in his life. He also never had any injuries to speak of. I know this as he was owned by my sister, who bought him when he was a 2 cell embryo :-)! So between my sister and me, we know every day of Gus' life.

When he came to me in June of 2009, NW Indiana, temperate climate, I had no idea that I could have done my own personal "brumby swap" study, observing how Gus hooves would respond to the sudden change in environment, from dry, hard and rocky ground 24/7 on search for food, to soft, wet and sandy with hay available 100% of the time (plus limited grazing). Unfortunately, I knew not much about hooves back then. Gus was incorporated in Molly's trimming schedule, which was every 8-10 weeks trimming by a professional farrier. Unfortunately, I have only very few pictures of Gus feet when he first arrived. And these pictures were not dedicated hoof pictures. They just happened to show the hooves in some meaningful way.

August 2009

I think what is pretty obvious from these pictures is that within 8 weeks Gus hugely overgrew his walls and bars above sole level. Also nice to see on the picture above is that even the sandy environment allows for some wear, in Gus' case, he wears the lateral toe and wall more than the medial. This is caused by his conformation and the fact that he rolls over his lateral side. This is 100% normal. Nowadays, since I understood that natural asymmetry of the hoof I am integrating this feature in my trim, so that Gus does not have to wait for 3-4 weeks until he would be able to wear this hoof in this way. I am now maintaining (to a certain degree!!) this natural asymmetry.

found Molly's training video

Yesterday, I suddenly remembered that I had kept Molly's training video. I had not watched it in a while as it was in a PC format and I have a Mac. But I decided I needed to see it because I wanted to find out if she already then showed signs of hitting the ground with her lateral toe on her FR. I found a conversion program and actually managed to upload it on youtube:

It was taken on Nov. 26, 2006 and Molly was 2 years and 8 months old. As far as I know this has been her second month of riding at the trainers. I did not yet own Molly, she was still owned by her breeder.

First and foremost, I fell right back in love again with Molly! She is such a sweet horse. Was and still is. A pleasure horse with a pleasure mind. And I would have bought her on the spot again!

I saw several interesting things on the video.

While I cannot see the hooves clearly it is rather obvious that Molly makes small sand clouds (indicating the toe hitting the ground) when landing with her FR much more than when landing with her FL.
When Molly backs up, she has a much easier time placing her FR back than her FL.
At some point in the video I hear the trainer saying "much better on this side". This is when he canters on the left lead. This is true for me too, she canters much nicer left hand than right hand! On the right lead, she "dives" in the corners.
As this video was taken PRIOR to her injury to the right hind leg (Molly got stuck in a fence om May 07, 2007, also still at her breeder's) I can finally rule out that this old injury (where she until today has a scar on the leg) had anything to do with her landing patterns.

I think it is now really clear that Molly's leg and hoof conformation developed out of her habit of her placing the FR back and her FL forward when grazing. Until today this is how she grazes preferentially, the FL is forward the FR backwards nearly always.

I recently came across an interesting article: "The embryology of the right front club foot", written by Amy Hayek, DVM, MA, CVA, CVC. It can be found here.

The first sentence reads: "The tendency to have a clubbed foot on the right, or to not extend the right front when grazing can be linked to embryological development of the G.I. tract and post partum sensory input from the environment that encodes for a gait pattern causing shortness of stride and compensation in the right front limb."

You will need to read the article to fully understand the connections. I cannot repeat this here. I wonder if this is why Molly has such a predisposition to place her FR back. I doubt, however, it is the only reason, as Molly always had plenty of grazing (or ad lib hay in slowfeeders), and at least for the past 2 years did not eat any concentrated feeds but only a ration balancing vitamin/mineral supplement, pre and pro biotics.

Sunday, November 25, 2012

plane of assessment

I found this article, written by Dr. Deb Bennett, PhD, in EQUUS issue 420, September 2012. I came across this author before, when researching hind leg conformation. Dr. Bennett has written a book on conformation.

Some time ago on this blog I have written about my difficulties deciding whether my horses are toed-in or toed-out. It depended on what angle I looked at the feet. Now, after reading this article, I realize that I am not the only one with this problem, only not many people seem to notice that it indeed IS a problem.

In order to properly assess the forelimb conformation one needs to position oneself in the plane of assessment which bisects the horse's knee.

None of the pictures that circulate in books and in the internet make this point, they always look from the front on the horse's leg.

I am going to have to look at my horses legs in a new light now.

Wednesday, November 21, 2012

Przewalski horse

The Przewalski horse (Equus caballus przewalskii) is the closest relative to the modern horse (Equus caballus caballus). In contrast to Mustangs, which are feral domestic horses (Equus caballus caballus), the Przewalski horse is the only true "wild" horse that is alive today, although severely endangered to go extinct. Only 2000 Przewalski horses are alive today. The natural habitat of Przewalski horses are the steppes of much of Eurasia.

People often assumed that the Przewalksi horse is closely related to the domestic horse, having split from each other around the time of domestication of the modern horse, around 6,000-10,000 years ago. However, as my colleague at Penn State discovered, based on sequencing the complete mitochondrial DNA of 4 Przewalski horses, the split between the 2 subspecies of horses occurred much earlier, ~150,000 years ago.

I recently browsed the internet to find some pictures of Przewalski horses' hooves. In my opinion, it is always good to look at some structure with respect of the evolution of that structure, as the horse just like we humans, are a product of millions of years of evolution by natural selection. Below are some pictures that I think stem from horses that really live in the wild and also in some native steppe habitat, in which this subspecies of horse evolved, and not an Animal Park, such as San Diego Animal Park, or Tierpark Hellabrunn in Munich.

I think what is pretty obvious is that these hooves look less than "ideal" for our understanding. There are horses with extremely chipped hoof walls, high heels, and some with extremely long toes. Yet, they seem to be doing just fine. What these horses do not seem to have so badly is underrun heels. Underrun heels, as far as I understand it, is the main cause of navicular syndrome. How these horses maintain a good heel angle despite a long toe is the question. Maybe the toe just does not stay that long for a long time.

One point of consideration is that these horses nowadays (and in contrast to much of their evolutionary history), do not face any pressures from predation anymore. The Sabre Tooth tiger has been hunted to extinction by humans. It most likely was the major predator of large herbivores such as the horses in the steppes. It went extinct 11,000 years ago, as modern humans settled the continents out of Africa. The threads that the Przewalski horse faces nowadays is habitat loss.

So the question is how their hooves would be if natural selection would actually operate on those horses as it has done for millions of years before today.