Sunday, September 12, 2010

Eureka!

I finally saw Spider trip today on the lunge line. And, I'm no vet, but if it isn't a sticky stifle that's bothering him then I'll eat my hat. It was really a textbook locking stifle trip. As he tried to bring his inside hind leg forward, his stifle didn't bend, causing him to trip as his toe dragged the ground. Classic.

Locking stifle, properly known as upward fixation of the patella, occurs when the stifle joint fails to release properly after extension. The stifle of a horse is analogous to our knee. Except that horses (and some other hooved mammals) have a unique adaptation that allows them to lock the joint so that they can sleep standing up. For a prey animal that evolved to live in open grasslands, the ability to sleep standing up is an important adaption. A sleeping horse that is already standing up is better able to run when startled. The caveat is that sometimes the mechanism can stick.

The mechanism itself is pretty simple. To lock the stifle, the horse simply extends the joint to it's fullest. When the joint extends, the medial patellar ligament hooks over a ridge on the femoral head, thus locking the joint and allowing the horse to sleep without falling down. To release the joint, the horse flexes it's quadriceps muscle, which pulls the ligament free of it's hook.

Just looking at how the mechanism works we can isolate two potential causes of locking stifles. A horse with fairly straight hind limbs will be more likely to have the mechanism catch. His natural conformation is such that just his normal stance will encourage the ligament to catch. And a horse with poor muscle tone, particularly poor muscle tone of the haunches (quadriceps, etc.) will not be able to release the mechanism properly.

What do I have? A horse with straight hind legs and poor muscle tone. Pretty much a recipe for locking stifle. I'm impressed he made it this far without ever having trouble with it.

I had already suspected a stifle problem (Thanks to Kate and Jean), but it is very nice to have a visual confirmation of that. It doesn't change anything, really though. I will continue working him as often as possible, doing lots of transitions, trotting over poles and trotting in the pasture on my little hill. When the vet comes out for fall shots I may explore putting him on estrone. Some horses with locking stifle issues benefit from estrone, some don't. But it doesn't seem to hurt and it's pretty cheap.

Spider did try to sneak away when I went to get him yesterday. As soon as he started to walk away from me, I turned around and got the lunge whip. He saw it and decided to let me catch him. Since he wised up, I decided to reward him by taking him out and letting him eat grass in the lawn instead of working. While he had his head buried in the grass, I took the opportunity to trim his mane up. He was beginning to look like a wild mustang, or perhaps an Andalusion. He has such a nice neck, it's a shame to hide it under all that hair. I banged his tail, too, while I was at it. Now he looks like a proper dressage horse again.

He gave me no problems today.

I also finally figured out how to manage the lunge whip, line and a camera. It was tricky and most of the pictures came out wonky, but I got the job done. So, here is Spider in action:


Not bad for a lame horse. *L*

6 comments:

  1. You can help a bit if you keep his hind toes rolled really well and try to keep a fairly high foot angle--I think for Russell it was 55 degrees.

    Legging up is, of course the first course of action, I totally agree. Back in the day, my vet also treated it with what I now call prolotherapy. It is NOT an injection into the joint, but kind of an internal blister (used to be iodine solution) in the area around the joint to cause in inflammation in the ligaments to they scar and tighten. It's what I have done to my knees and it really helps.

    Fun trying to take the lunging pictures. Most of them don't come out well, but out of a bunch you usually get one or two. Spider looks really nice in action. What a good boy.

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  2. He looks good ;-) I liek horses with short mane. Today in fact I am going to trim Teena's mane.

    I did not know anything about stifle. Thanks so much to write all these infos.

    Have you got any ideas for stiff shoulders. After her massive infection AND laminite to right ant 4 months ago, Teena has very stiff shoulders.
    What kind of work shall I do?

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  3. Hooray for confirmation! It's so good to know you've actually found the problem. Spider looks pretty darn good.

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  4. WOW - he looks awesome in such a short period of time! That must be because you work him properly every time! One day I will get Sam looking like that! Well done!

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  5. My horse Teddy developed a sticky stifle years ago. The estrogen shots made it possible for me to work him through it as the estrogen has a calming effect as well. His stifle would lock and stay locked and he would panic.

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  6. I had my 4 yr old Standardbred filly operated on in February 2013. She had a Medial Patella Ligaments Splitting done on both stifles as she was a really bad case.

    You can see an account of her progress which I keep as a day to day diary on http://www.horse-problems.blogspot.co.uk if any one is interested.

    So far, it is not looking too promising.

    ReplyDelete

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