In a nutshell:
- Healthy bars end at the midpoint of the frog
- they are straight instead of bowed
- they stand up, not pushed over onto the sole
- they are not so long and deep that you can't see the bottom of the collateral groove
- really healthy bars point toward the frog and not the toe
First we have to know what the internal bar structure looks like. In this photo you see a pretty nice hoof, the heels were nice and wide and the corium was healthy. You can see that the bar corium (outlined) angles in from the heels to the midpoint of the frog.
(I encourage you to click on these photos and zoom in to see the detail, they are important.)
|Photo by Cheryl Henderson|
|Photo from HP Hoofcare|
In this, really unhealthy, hoof you can see the bar corium (bright red) points straight toward the toe but they still end at the midpoint of the frog.
|Photo from HP Hoofcare|
What all these hooves have is common is that the bars all end at the midpoint of the frog. That is true whether they are healthy or terrible. So when I trim I try to get the bars to end at the midpoint of the frog- to keep the external structures similar to the internal structures.
The angle is a different story. You can tell by the above hooves that if the hoof is contracted and unhealthy the bars are going to point straight at the toe. You can't change this by trimming, only the full weight of the horse on the heels will get them to open up and point the bars toward the center of the hoof. What you can do is make sure the bars aren't so long they are digging into the hoof and aren't laid over so they are suffocating the sole. Essentially, you want to trim the bars to give the horse comfort; that will facilitate the hoof transforming into a healthy shape.
The following two photos show my second trim on a contracted hoof. I use the bar lamina to outline the bars from the heel turnaround (seat of corn) to the frog. I then try to make the bars as straight as possible and I slope them "downhill" from the heels to the frog. I do this so the bars are "passive," meaning that they don't bear weight which is especially important if the bars are impacted. While I do this I try to take off as little sole as possible, this can be a very time consuming process of taking off thin slivers at a time. It takes a sharp knife, a steady hand and lots of practice (I admit, I still need more practice) and can be made even harder by a fidgety horse.
If you can't see the lamina the bars are laid over the sole. If there is a black line along the bars it means they've laid over the sole and trapped dirt and thrush under them. That trapped dirt and thrush will destroy any sole underneath it, not good.
This next photo is after my first trim on a pony. The circled areas show bruising from overgrown bar, bruises that weren't visible until I started pulling the bar off the sole (Excess bar puts too much pressure on the corium below it, crushing blood vessels and creating these bruises.). Lots of horses have these bruises but you don't see them because the bar that causes the bruises also covers them up.
|Bars should look similar to this|
Here's a how-to guide to trimming bars similar to the way I trim: http://www.thehorseshoof.com/trimmingbasics3.html.
Questions? Please comment.