DIGITAL CUSHIONS and LATERAL CARTILAGES
Please watch the video above first!
This is probably the single biggest eye-opener that there has been to me when I started cutting cadavers. To see the difference in the Digital Cushions and Lateral Cartilages from cadaver to cadaver.
When a horse has not been working or has been toe striking, as most horses unfortunately do due to ignorance, the Digital Cushions consist of fatty tissue and the Lateral Cartilages are thin and without the essential blood vessels. When one puts thumb pressure on the heel bulbs, it is soft and often the horse is tender just from that pressure.
On the other side of the spectrum, when a horse has been worked and has a good heel strike, the hard Digital Cushion consist of fibrous tissue and the Lateral Cartilages are wide (thick) and has big blood vessels in them. It is firm under the same thumb pressure I described above.
It is important to note that as the Pedal bone supports the front of the foot, so does the Lateral Cartilages support the back of the foot. They are meant to be thick, strong, filled with blood vessels and flex under loading.
At the top of this page is a video comparison of two Digital Cushions and Lateral Cartilages where one can see the difference clearly.
Take note of how thin the Lateral Cartilage is with few small blood vessels in the foot with the soft Digital Cushion and how thick the Lateral Cartilage is and how many and big the blood vessels are in the foot with the hard Digital Cushion.
Without getting into too much detail, it stands to reason that with that many big blood vessels, there are more and better blood supply (and therefore nutrients and oxygen) reaching the various parts of the foot, but it is also this blood supply that has a hydraulic effect when it comes to shock absorption when the hoof lands and takes the weight of the horse on it.
Watch the video comparison in the header above to see these two cases compared in real life!
In the picture on the left you see a firm Digital Cushion with thick Lateral Cartilages and many big blood vessels in them.
On the right you see a soft fatty Digital Cushion with thin Lateral Cartilages and almost no blood vessels.
The interesting fact is that the one on the right, with correct trimming and proper exercise could in time have looked like the one on the left….nature’s wonders!
I would now like to show you where exactly the digital cushion is located. Here is a picture where I have marked the digital cushion for you. I can visualize the foot landing, how the bones move during the stride and how they push back and down into the digital cushion….can you visualize it?
Now let’s take a look at two cadavers and see what we can conclude from them.
Please Note: When looking at these pictures, don’t be tempted to think the Pedal Bones are or are not almost ground parallel as they should be. Cutting a hoof like this, does not show the angle of the Pedal Bone to the ground as the cut is where the back (curve) of the Pedal Bone is at it’s highest.
The foot on the left clearly has a long toe horizontally and has “squashed” the Digital Cushion almost flat…very little shock absorption going on here. There is a likelihood that this could have made the horse sore in the back of the foot. Together with the long forward toe, which would cause late breake-over, this horse would definitely have been toe striking. The one on the right is clearly a more upright foot, break-over would have been better and see how much Digital Cushion is under the Navicular bone!
It is also important to take note that the Pedal Bone in the hoof on the left has “sunk” below the top of the hoof capsule, while the one on the right is in line with the top of the hoof capsule. This means that we will have to think about the game plan for trimming in order for the correct hoof mechanism to take place, which will effectively “draw” the Pedal Bone up higher.
We’ll look again at these two cadavers when we talk about Soles under Trimming.
Also notice how flat the sole of the left hand foot is while on the right some concavity can be seen.
Considering how much smaller the bones in the foot on the left is, if this foot was in the same health as the one on the right, the foot would have been much smaller (heel to toe) than it is here (because it would have been upright, like the one on the right) while comparing them like this there is little difference in size from heel to toe.
Interestingly, notice how wide the whiteline is in the one on the right in comparison to the left. Is there someone that has an explanation for this?