We’ve only uncovered ¼ of his skeleton…

Elisse Miki
3 days ago
4 min read

FROM THE BONE LAB

What His Bones Are Already Telling Us

We have excavated approximately one quarter of this horse. And already, there is a lot to talk about.

This horse was donated to the Bone Lab Project by an owner who deeply valued the education that could continue to come from his body after his death.

He was an OTTB with a long and complicated clinical history, including numerous neurological symptoms.

Throughout his life, he was assessed by many veterinarians, but a diagnosis that fully explained his clinical presentation was never reached. His owner knew there was still something incredibly valuable he could give us: the opportunity to learn from his bones.

So that is exactly what we are doing.

We are excavating him slowly, documenting what we find as his skeleton emerges, and looking at each finding through the lens of anatomy, biomechanics and whole-body function.

And we are only about ¼ of the way through. Here are three of the findings so

far.

FINDING 01: L6–L5 Vertebral Fusion

X-ray view of fused L5 and L6 vertebrae in a horse spine

One of the first major findings appeared as we began removing his lumbar spine.

I went to lift L5 and L6 separately.

They came out together. The two vertebrae had fused.

What are you looking at?

Normally, L5 and L6 are two distinct vertebrae with an intervertebral articulation between them. Each segment contributes to the collective movement and load distribution of the lumbar spine.

In this horse, L5 and L6 had become fused into a single unit. Movement between those two vertebrae was no longer available in the way it would be in a normal lumbar spine.

Why does this matter?

Because the horse still has to move. If movement is lost or substantially reduced at one spinal segment, mechanical demand doesn't simply disappear.

It has to be redistributed.

The segments above and below may be required to accommodate different movement and loading demands as the body finds another way to accomplish the task.

This is why I rarely look at a spinal finding as an isolated event.

The spine functions as a system.

And interestingly, another significant finding was waiting for us farther up that same spine.

FINDING 02: Significant Bony Remodelling at T18–L1

Comparison of abnormal and normal T18 and L1 horse vertebrae joints

This one becomes particularly striking when you compare it with a normal specimen.

At the articulation between the final thoracic vertebra, T18, and the first lumbar vertebra, L1, there are multiple areas of substantial periarticular bony proliferation and remodelling.

When the joint is pulled apart, you can appreciate just how much the architecture around the articulation has changed.

Compare that with the normal specimen below it: Clean joint margins. Clean articular surfaces. No comparable proliferation of bone.

Why does this matter?

T18–L1 sits at an important transition between the thoracic and lumbar regions of the spine.

Changes to the architecture surrounding an articulation can influence how that region moves, how it accepts load and how forces are transferred through the surrounding spinal segments.

Bony proliferation and periarticular remodelling can be associated with degenerative joint processes, which in the living body may be associated with pain, stiffness and altered mobility.

Again, we cannot look at a skeleton after death and tell you exactly what this individual horse felt.

But we also shouldn't dismiss structural changes of this magnitude as meaningless.

And remember what we just found farther down the lumbar spine: L5–L6 were fused.

Already, we are beginning to see that this wasn't simply one abnormal structure in one isolated location.

FINDING 03: Mineralization/Ossification Scapular Cartilage

Ossified scapular cartilage sample from horse dissection analysis

Then we moved away from the spine.

And found another interesting structural change.

Along the dorsal border of the equine scapula is an extension of cartilage called the scapular cartilage.

In this horse, a portion of that normally cartilaginous structure had undergone mineralization/ossification, creating a hard, bone-like projection from the dorsal border of the scapula.

Why does this matter?

The horse's scapula does not form a conventional bony joint with the thorax.

Instead, the forelimb and scapula are suspended against the trunk through muscle, fascia and connective tissue, what we commonly refer to as the thoracic sling.

The scapula needs to interact with the thorax as the forelimb moves and the trunk is supported between the front limbs.

When the physical properties of a structure change, its mechanical behaviour can change too.

So this is another finding worth considering within the context of the whole horse, rather than simply an interesting piece of bone.

And this is where the story gets bigger.

It would be easy to look at these three findings and think: "Wow. This horse had a lot going on."

He did.

But here's the part I really want people to understand: This is not the first horse in which I have found significant skeletal changes like these.

Far from it.

Through the horses I have dissected and composted, I have repeatedly found substantial structural changes within the skeleton...sometimes in horses whose bodies gave us far more information after death than we were ever able to access while they were alive.

The difference now is that I am intentionally documenting it.

I want you to see the bones as they emerge.

I want to show you what we find, where we find it, what normal anatomy should look like, and why these changes may matter to the function of the living horse.

Because when we look at a horse from the outside, there is an enormous amount we simply cannot see.

But the bones allow us to look from the other direction.

They allow us to ask:

Where was movement being lost?
Where was load being redistributed?
What other structures may have been asked to compensate?
And could some of what we see clinically make more sense when we understand what was happening underneath?

That is what the Bone Lab Project is really about.

Not collecting unusual bones.

Learning from them.

And we're only ¼ of the way through.

There is still a tremendous amount of this horse left to excavate.

We have already uncovered additional findings that deserve a much deeper conversation, and I will be sharing those as we continue working through his skeleton.

So this isn't the end of his story. It's really just the beginning.

His owner decided to compost him because she believed there was still something he could teach us.

I think it's safe to say she was right.

The bones never lie.

— Elisse | EQ Therapeutics | The Bone Lab Project