Tuesday, September 20, 2011

Equine TMJ

You are a few days out from a dental cleaning.  You start to chew your dinner and are rudely stopped by gnawing (pun intended) pain where your lower jaw meets your skull.  The next day is followed up with a dull headache and you find yourself reaching for the ibuprofen by mid-morning.  You make a mental note to start rinsing with mouthwash to prevent tarter build up, because the dental hygienist's dance over the surfaces of your teeth felt more like a Stomp routine than you would care to admit.  You avoid tough foods for a couple days and keep the anti-inflammatories coming until it is no longer necessary to make faces while chewing solid foods.  That is, of course, if you are lucky.  For some, the pain may be chronic.

What am I writing about?
The TMJ.

The TMJ is observed as the two bumps behind Harley's eye and next to the buckle on his halter.

That's the Temporal Mandibular Joint (TMJ) and it affects horses as well as humans.  The trouble with horses, though, is that they cannot verbalize their pain.  And unlike the story above, a dental appointment should not be the cause of TMJ pain in a horse.  If the speculum is left open too long or too wide, the TMJ and associated nerves may be damaged.  One could argue, that a sedated horse is at an even greater risk, because he is unable to express his discomfort even though the muscles and nerves are still under strain if the speculum is being used improperly.  But as already stated, the dental appointment should not be the cause of TMJ pain.  A professional equine dentist will know how to use the speculum safely.  TMJ pain is more likely caused by malocclusions.  A malocclusion is a misalignment of the biting surfaces of the teeth.  This is where we see that floating is not the end-all, be-all of equine dentistry.  Your horse's dentist must also know how to evaluate and correct malocclusions.  If the biting surfaces of the upper and lower jaw are imbalanced, your horse will not be able to close his jaws, chew, or relax the muscles around his TMJ properly.  This will also put strain on the sensitive nerves associated with this all-important joint.  If nerve damage results, repair may be very slow or impossible even after corrective dentistry.

A horse suffering from TMJ pain will certainly have difficulty eating or may experience "mystery" colic episodes.  The problem will also extend to the saddle.  A horse with TMJ pain cannot comfortably accept the bit.  He may not be unable to relax his lower jaw or comfortably close his mouth while "on the bit".  Unfortunately, this problem is often corrected by applying a tight noseband.  Fixing the mouth shut will increase the discomfort.  Horses in pain will act out in various ways, many of which are contrary to a safe riding horse.  This is just one example of a justification for evaluating "the whole horse" when problems arise.  TMJ pain cannot be trained or rested away and will not improve with a tack or bit change.  Regular dental appointments with a qualified professional are the easiest and safest way to ensure that your horse is free of TMJ pain.

Harley's dentist always checks for TMJ pain.  He is a very knowledgeable equine professional.  I feel very fortunate to have him in my area.

Feeling the TMJ.  The nerves extend toward the mouth.

Always stand next to your horse, not directly in front of him.  If he feels sudden pain when you palpate the joint or nerves, he will not be able to help bopping you with his head, no matter how much he loves you or how well you have trained him.  TMJ pain really hurts.  You should be able to feel the nerves that extend from the TMJ to the mouth of the horse.  If you apply pressure to these nerves and your horse does not react, his TMJ is not sore.  If he reacts by moving away, flinching, tilting his head or another strong reaction, your dentist should pay him a visit.  Every source that I read stresses that this small joint can cause a great deal of pain which can seriously impact your horse's health and your safety as his rider.

I am not an equine dentist, so in the words of one of my favorite childhood TV shows, Reading Rainbow, "don't take my word for it".  There is a wealth of knowledge online, so get reading!  Or better yet, ask your equine dentist about the TMJ and how to check for soreness.  My hope is just to plant the seed of awareness.  I remember when Harley's dentist first mentioned this joint.  My response was,

"The TM-what?"

Related Links:
Advanced Equine Dentistry
Equine Dental Care
Horse or Equine TMJ and Joint Problems


  1. I just checked Fred's TMJ, I think he's fine...He didn't even blink. :-) I wish I had a horse of my own that I could check these things you point out. Your knowledge is invaluable!

  2. Very important - many horses have dental issues leading to TMJ issues, which affect the whole body - and people then wonder why their horse can't bend in one direction . . .

    Many equine dentists don't do enough to be sure the incisors are correctly aligned - that can really make a difference to TMJ alignment. But that requires using hand tools and being careful and slow and many equine dentists and vets overuse power tools and are in a hurry.

  3. Thanks again for this! When I've got some time on my hands I'm going to visit those links you've put up- I don't know nearly enough about equine dentistry.

    I've heard it said that the TMJ joint acts as ancillary heart for the horse similar to the hooves. I don't know enough about it to figure the validity of that statement but I thought it was an interesting thing to say.

  4. Mary- I am glad Fred's TMJ is not bothering him. Even dogs need dental care. When I had cats, I had their teeth cleaned. I wish a horse for you, too!

    Kate- I agree 100%. I cannot overstate how happy I am with Harley's dentist. He has tremendous horse sense and sincerely cares about horses. I watched him perform an incisor reduction on Harley. That is on my list of teeth topics. ;)

    smazourek- I also wonder what that means. You should blog about it when you find out! Harley's dentist told me that the tongue is connected (ligament-wise, I think) to the front legs. That one blows my mind, even though I do not yet understand what it means.


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