Laminitis: Hoof wall growth

The first thing you need to know about the hoof wall is that it is actually composed of three different sections:

• the distal hoof wall/pigmented wall/stratum medium, 
• the water line/unpigmented wall/stratum internum
• the white line/epidermal lamellae

To understand hoof wall growth we also need to focus on the lamellae, of which there are four types:

• Primary Epidermal Lamellae (PEL)
• Secondary Epidermal Lamellae (SEL)
• Primary Dermal Lamellae (PDL)
• Secondary Dermal Lamellae (SDL)

The lamellae from the epidermis (outside of the hoof) interlock with the lamellae from the dermis (inside of the hoof) by means of a basement membrane. "The basement membrane is a thin, unbroken sheet of extracellular material, partitioning the dermis from the epidermis (Pollitt)."

Each one of the SEL (the little fingers hanging off each PEL) is attached to the basement membrane by a hemidesmosome through anchoring filaments. Anchoring filaments are composed of a glycoprotein molecule called laminin-5 and a protein called BP-180.

Following along so far? Okay...

The coronet band is constantly creating new cells for the hoof wall, which means there needs to be a mechanism to move the already existing wall down towards the ground to make room for the new cells. To do that, lamellar remodeling enzymes called matrix metalloproteinases (MMPs) come through and pop the hemidesmosomes off the basement membrane (not all at once, mind you), tissue inhibitors called TIMPs then turn the MMPs off, and the loosened cells then move downward and reattach lower on the basement membrane by the anchoring filaments.

This process happens constantly in order to keep up with the growth from the coronet band. The MMPs, TIMPs, and anchoring filaments are always working in a very delicate balance to keep the hoof wall growing and replace material lost at ground level.

And that's hoof wall growth in a nutshell.

Upon further examination, Bowker's theory of hoof wall growth doesn't differ terribly from this, he just posits that the PELs actually contribute cells to the stratum internum to increase hoof wall thickness closer to the ground. For the purpose of understanding laminitis that isn't terribly important (just interesting).

All the info in this post I learned from reading the work of Chris Pollitt, I'll provide links later on. You'll notice that I've made a few words a little more "obvious." Try to remember those, they'll be important later.

Weekend update

I'm working on the laminitis posts, here's a heads up that there will be multiple ones and some of them will be pretty technical, there's no way around that. I'm going to start with a post on how the hoof wall grows but I've still got to wrap my mind around Pollitt's theory vs. Bowker's theory. They aren't the same, not at all.

In the meantime, here's a video showing that bum squeeze I was telling you about a few weeks ago. The only thing I was doing was squeezing my cheeks, I wasn't doing anything with my hands or my legs except get him organized.

Gwen did some really good work today. I put two cones up and we worked on walking to a cone, turning around it and then walking to the other cone. She did pretty well, the steering got a bit wacky at times (she was very interested in the barn for some reason) but we eventually ended up where I wanted to be. We even finished up by walking in a circle around a cone, I was pretty pleased with that. She's getting to be a riding horse, by golly!

Writer's block

I haz it. I can't think of anything I want to talk about that would be interesting. I just got Pete Ramey's very expensive new book and part of me wants to snark on that, but I just snarked on AQHA and too much snarking gets old fast.

I could talk about our latest nocturnal training sessions, but talking about training for ground tying, pose and leg lifts also gets mad boring without any visuals to explain what I'm doing.

I could talk about my last ride on Gwen on Saturday, where she was really good until she decided she'd rather graze than move forward and so decided backing up to stay in the grass was the better option. Unfortunately she backed my helmet right into a tree branch and scared herself when it made a sound (which only resulted in a 3-step spook, good for her!)

I could talk about my last lesson where we worked on leg yielding and I innocently pretended I didn't know what I was doing so I could pick her brain on the aids. But most of you know how to leg yield so that's not too interesting either.

I could talk about how I trimmed Zippy again last weekend and it looks like I've finally come to the end of his impacted bars. YAY! The owner lunged him before I worked on him and I was delighted to see that he was completely full of beans, bucking and kicking- horse felt good! Still lame, but a lot  better than he has been. I did uncover some disease pockets in his right fore though, that was a little worrisome.

But nothing seemed to be entire post worthy all on its own. Anyone interested in what I have to say about laminitis? I've been meaning to do some more research on that anyway.

Ah well, I guess you'll just have to look at this strange photo of Coriander eating dinner last night. Hopefully I'll come up with something interesting to say soon.

In the dark

Daylight Savings day is my least favorite day of the year, it marks the beginning of three months of darkness for me. Three months when I only see my horses in the light on the weekends or holidays. Ugh, winter.

Anyway, this year I'm going to try to make the most of it. I asked Mark to set up a light on the front of the barn so I'll have a place to work in the evenings and I plan to pick up all the projects that fell by the wayside this year. That means head lowering, pilates, standing on the mat, leg lifts, and working on balance in small circles (AKA picking the shoulders up and out instead of falling in on them).

I plan on trying to ride Gwen on the weekends, I'm hoping that when the snow covers the grass she'll be able to focus better, while Coriander is basically getting the winter off from riding. In the meantime I've started dressage lessons so that when Coriander and I get to work next spring I'll be better prepared for our next step in training.

Speaking of that: During my lesson we worked on walking and halting "on the bit." She had me squeeze my buttocks to get the horse to lower his head and lift his back, then I got him to go long and low by squeezing my cheeks while he walked. I went and tried it with Coriander later that day and it worked, he arched his neck down immediately.

Why does that work? Is it a pressure point on their backs? I would be afraid to rely on that trick though, does it teach the horse anything about carrying their bodies or is it just a physical response? I want a little more than just a reflex to get my horse stretching over his topline (not to mention that my tushy gets tired and it makes me feel like I'm perching on top of the horse). I'll have to ask her about that during my next lesson.

Dr. Kellon's nutrition course started this week too. I mentioned I'd give out little tidbits that I've learned along the way, so here's one for week 1: You almost never need to supplement vitamins A, D, K, B-12, and C in your horse's diet.

Wow, that seemed like an incredibly random post. Might as well keep adding to it then- I added another video to my last post. I'm really starting to wonder if the judges for AQHA are legally blind.

Really AQHA?

Apparently I'm on a video kick, cause here's another one.

Some genius AQHA judge said this horse was world champion quality and they proudly declared this on facebook:

2011 AQHA Yearling Stallions World Champion

I'm no professional show judge, but I would have DQ'd this horse immediately. Anyone else agree? Already lame at one year old and fat as a slaughter-bound pig to boost. Wanna place bets on this horse's future?

PS- is the lip chain really necessary? I thought the ideal quarter horse was supposed to be calm and easy to handle (Gwen notwithstanding). Even the stallions.

Edited to add a video of AQHA naming yet another lame horse world champion, this time the performance halter champion. This is even worse, horses are supposed to earn points under saddle to qualify for performance halter. Was this horse lame for all his under-saddle classes too? What is wrong with these judges?

Always remember...

It's about having fun!

A real ride

Honest to goodness, I had an actual ride on Gwen today.

First of all, I took her over to the mounting block and got on without putting a flake of hay down first. She stood like a stone until I was mounted and she was rewarded. Brilliant.

Then walked up the hill around the barn, and she halted when I asked her to before turning into the Christmas tree field. Excellent.

We turned into the field and hit a bit of a snag- I wanted to turn around and head back, she wanted to graze. Grazing wasn't on my agenda, so we had to do some hip yielding until she decided to just stay in the direction I pointed her. Points for me on sticking to my guns.

Then she walked down the hill and turned toward the barn when I asked her, and halted again when I asked. Awesome.

Oh, and guess what? She backs under saddle! I asked her on Sunday and she just glided backwards- there was no pushing through the reins or trying to slide left and right, she just stepped back. So cool. I asked her again today with the same result, flowing backwards. All of our ground work has really paid off.

We've now got go forward, turn, halt, and back. The building blocks for making a riding horse.

It was a simple, short ride by most standards, but considering how far we've come I had to crow about it!