"Headshaking is a condition of horses in which the horse shakes, flicks, or jerks its head uncontrollably without apparent stimulus (without any obvious cause)."
Headshaking happens for a variety of reasons, again, check out the websites for a better explanation, but there are two basic causes: abnormal function of the trigeminal nerve and/or exposure to bright sunlight.
In February, Izzy went through a weeklong period of extreme sneezing attacks while in his stall. I chalked it up to an allergy and watched for any nasal discharge. The episode passed and we moved on to lunging and under saddle work.
While riding him bareback, he started flinging his head pretty violently, but I chalked it up to nervous tension. Once I started riding him with the saddle, the head jerking was accompanied with repetitive sneezing. I called the vet. His tentative diagnosis was headshaking. I was crushed.
I started researching the condition and was somewhat encouraged. Izzy had only some of the signs, and only when working. As suggested by my vet, I started doing different tests to find out what triggered the headshaking and sneezing. I kept a detailed log of weather conditions and Izzy's response.
For most headshakers, sunlight is a giant trigger, not so for Izzy. I did lots of hand walking and lunging in the arena on the brightest days possible with the sun high in the sky. For some of the tests, I turned Speedy out while I walked Izzy with my handystick in hand (for protection). On those days, Izzy was the most relaxed and completely symptom free. Bright sunlight does not seem to be a trigger.
Since sunlight doesn't appear to be a trigger, I started working on other therapies:
- I tried handwalking and turnout on windy days. Again nothing happened.
- I ordered Quiessence, a magnesium supplement that helps calm the nerve firing. Izzy's been on it now for a week. He has improved, but I am not sure that is the reason. Full efficacy should be seen after several weeks.
- With my vet's endorsement, we tried Azium, a steroid used to treat allergic responses (among other things) for four days. While I didn't see an improvement, I am still waiting to see what happens when the Azium leaves his system. Azium is fast acting and lasts for several days, so we might see a worsening of the sneezing if the Azium actually did anything.
- There is another drug that we can try that has proven to be fairly successful, Cyproheptadine, but it needs to be administered orally twice a day, which would be difficult for my barn owner. We're saving that therapy for last.
- I switched from the Micklem bridle (designed to avoid the facial nerves, but who knows) to a standard snaffle bridle with no flash. Again, he was better, but I am not sure that was the reason either.
- I added a half pad to the riser pad (with a square pad) since my saddle is a bit wide for him. I also modified my tacking up process a bit which has eliminated the bit of humping up he was doing as he walked out of the cross ties. That simply seems like a baby horse issue, but it was a source of tension.
- I added a nose net to my bridle. Whether coincidence or not, that was the first thing that seemed to have made an immediate difference.
The second thing that Izzy has going for him is that the trigeminal nerve is not damaged. There is not anything wrong with him other than the fact that something is causing that nerve to misfire. This is a good thing. If we can eliminate the trigger, we can help him work more comfortably.
Izzy's symptoms do not seem to come from the bright sunlight, but rather from tension. My vet agreed with this assessment. Some horses who experience headshaking only show signs when asked to work. As their tension levels rise, the trigeminal nerve misfires and the headshaking begins. Izzy's symptoms are mostly sneezing, so we are addressing this as a training issue - as in how do we reduce his tension?
How are we doing that? I'll share more in another post. We don't have a concrete answer yet, but we're chipping away at the problem, and I am still having fun riding him.
Check back for more ...