The Equine Practice Inc, Travels With Doc T

Incisor Reductions In Equine Dentistry

Incisor reductions are still a contentious debate item outside of the veterinary world. Let’s start with a little history.

In the early 1900’s there are reports of rasping the incisors but it was short lived.  Then one morning in the mid 1990’s a non-veterinary equine dentist in a parking lot of the Saratoga harness track in NY climbed into the cab of another non-veterinary equine dentist (a personal friend).  He said to my friend, “Hey guess what? I’ve developed a new profit center!” He then proceeded to describe the filing of the incisors “because the customer can see that.”

In a short time, this process was introduced into the veterinary world and called “incisor reductions.” The main veterinary spokesman for this developed the idea of “lateral excursion” of the mandibular incisors against the maxillary incisors. He published a paper where he used a marker to show that this excursion was often not equal in distance and that filing the incisors would alleviate this inequality and thus “balance” the mouth. There was an assumption that these horses were sedated which may have altered the results of the measurement.

In the late 1990’s I was asked to present to the alumni of the Cornell vet school my technique of floating horses along with another vet from Texas. I watched him mark the incisors with a Sharpie ink marker and then cut off the excess incisors in the heavily sedated horse with a Dremal tool. Many of us “older” vets at the time looked in amazement and then conferred with each other. We all thought that this was just a gimmick because the instructor never revealed to us the real purpose behind the reduction other than to “balance” the mouth. In other words, he never explained what this procedure solved other than balance, which no animal or human really is. Just look in the mirror to see your own asymmetry.

Veterinary Meetings

In 2002 I attended the British Equine Veterinary Association’s meeting in Glasgow Scotland. This is the equivalent of our AAEP (American Association of Equine Practitioners). I was one of 6 Americans attending and only myself and one other vet from the US were there for the dentistry component which was a major section of this meeting. Dr Paddy Dixon was the lead of the section and he is currently the head of surgery at Edinburgh Veterinary College, co-author of “Equine Dentistry” and the author or co-author of hundreds of papers on dentistry in horses.

The BEVA program director found out that I was in attendance from the USA and so she set up a lunch meeting for me with Dr Dixon – just the 2 of us.

Dr Dixon asked me then what I thought of incisor reductions. I answered that I thought it was unethical and unjustified in equine dentistry and that all the “problems” our eyes see in the incisors (uneven bite alignment) are a secondary effect from altered movement of the jaw and tongue caused by oral pain. I concluded that if we correct the cheek teeth and remove the pain causing points then the incisors will take care of themselves.

Dr Dixon popped up his eyebrows and looked at me for a minute. Then he said, “We are now finding this same conclusion and here in the United Kingdom and we are rapidly moving away from incisor reductions.” He further explained that through electron microscopy, the prisms that make the enamel of the incisors are different and softer than the prisms of the cheek teeth enamel. This goes with the idea that an unbalanced incisor occlusion would be secondary to something else.

Two months later in December 2002 I attended the AAEP meeting with a special wet lab for dentistry in Ocala FL. Here Dr Lowder from the Georgia vet school also said at his station that we were “rapidly moving away from incisor reductions.” I thought it was odd that they both used the same phrasing, but I also felt that I had been validated. Incisor reductions had no valid place in routine equine dentistry.

Since 2002, there has been little said for the performing of incisor reductions in the veterinary literature or at meetings other than the occasional reports (as well as personal communications to me) of horses losing their lives after an incisor reduction had opened a pulp chamber creating a life ending infection in the jaw.

The Equine Practice Inc, Travels With Doc T

The temporomandibular joint in a horse is just in front of the ear and connects the jaw bone to the head.

The Temporomandibular Joint

The only group still promoting the reduction of incisors is Advanced Whole Horse Dentistry. They believe that there needs to be a 3 point balance between the incisors and the temporomandibular joints (TMJ’s) before any cheek tooth work can be done. Simultaneously, veterinarians from the vet school at Saskatchewan Canada have performed extensive research (both active experiments as well as retrospective studies) determining that horses do not suffer from primary temporomandibular joint disease or dysfunction. These studies are very interesting. This statement comes from one study: “Horses with degenerative joint disease (DJD) of the temporomandibular joint (TMJ) have been reported infrequently, with the majority of cases describing the disease as a consequence of an earlier traumatic event. A case of clinically significant TMJ-DJD due to a non-traumatic event has not been published.”

This aligns with a personal communication from Bill Bradley, DVM from NY who purchased a nuclear scintigraphy machine for his new equine hospital. He told me that every horse that came in for a specific joint bone scan was actually given a full body scan so he could learn the details of his new diagnostic machine. He told me that in every horse scanned, “the TM joints lit up like a Christmas tree.” He further said that he would never scan these joints in the future because it would be pointless. I reminded him that these amazing joints move on average 25,000 times a day (range is 10,000 to 40,000 according to Dr Katherine Houpt, professor emeritus at Cornell vet school in behavior). Because they are the most active joint in the horse, it would make sense they would always scan positively due to activity and the associated blood flow.

The Teeth And A Boat

The debate still goes on whether to file the incisors. In my experience I have not seen a reason but this is because of a paradigm I would like to explain here. Imagine a boat moored to a thick wood piling in the water. As it gently rocks over time from wind and waves it wears a notch in the wood. Does the notch in the piling prevent the boat from moving? No. It is a result of the movement of the boat which continues unimpeded. With this paradigm, couldn’t the incisors be worn due to the movement of the jaw and tongue? Does this uneven wear impede the movement of the jaw? I say it doesn’t just like in the boat example.

This brings about another point. What causes the incisors to wear? In the 300 horses I photographed for my aging project I noticed several things. For at least half of the horses, when the lips are raised and the incisors are photographed straight on, there is a relaxed space between the occlusal surfaces with the tongue present between them (see the image at the top of this post). In fact, I’ll bet that your incisors (really all of your teeth) right now are not together. So where is this idea that horses need a 3 point balance when in the normal state the incisors don’t come together? If a chew takes 1 second to perform and there are 86,400 seconds in a day, then on average the horse is NOT chewing for about 2⁄3’s of a day.

In addition, with slow motion videography it is seen that the tongue exits and enters for every bite of food and every harvested parcel of grass when grazing. More evidence that the incisors don’t really serve any purpose in horses other than defense is that all ruminants have no upper incisors. And horses that have lost their incisors (trauma, EOTRH) still harvest grass with ease. Have you ever seen a skinny parrot mouthed or sow mouthed horse where the incisors don’t even meet?

The Equine Practice Inc, Travels With Doc T

All but 1 incisor lost to EOTRH (disease of the jaw bones at the incisors). This horse harvests grass effortlessly.

Where Is The Proof?

Finally, if we really want to put the need for incisor reductions to rest then there needs to be a study where only the incisors are reduced in a horse with a bit or chewing issue. After this we need to determine if the issue has been resolved. This then would suggest that there are certain issues in a horse’s life that can be resolved with only an incisor reduction. In my practice I have done enough horses where the cheek teeth are addressed without incisor work that resolve bit and chewing issues so I don’t think we need to perform that experiment. But there have been no studies to show that incisor reductions alone actually give an improvement in these issues because all equine dentists who perform an incisor reduction also perform point removal at the same time.

As a veterinarian with over 70,000 observations I look forward to learning new things but I also look backwards for patterns to learn from. So far I have found no evidence for incisor reductions and will not be adding that to my techniques.

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Comments 16

  1. I’ve never had any of my vets, float nippers. I am also quite dismayed about the # of male horses I’ve encountered, who’ve had their tusks clipped off. This practice is absurd! When the insides of the teeth are exposed, there’s a risk of abcesses, necessitating the extensive use of antibiotics,& extraction of the mutilated teeth. A very expensive, & difficult procedure in the horse. Not to mention, the totally unnecessary suffering inflicted on the horse, had his teeth not had been mutilated in the first place! A bit, properly fitted, will NOT interfere w/ the tusks of a male horse. I know this for a fact because I’ve owned more geldings than mares, & I’ve never had a problem w/ so-called bit interference. If one really thinks It’s a problem, switch to a hackamore, please!

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      Thanks Sara. Canines have a pulp center that when exposed may become infected. It is the movement of the tongue that shapes them into daggers for tearing flesh. The girls would rather kick so canine weapons are not needed though a few will have very small ones. They can often be assertive and not a good horse for the timid.

  2. Ive never had it done, but appreciate a heads up on what misguided dentists might think of next. Solid reasoning, thank you!

  3. As a human dentist, I find the removal of incisor tooth structure to be problematic. Here’s why…the incisors form the most anterior portion of a bony system….TMJ bering the most posterior, molars are in the middle, and the incisors are most anterior. If you change anything in the front, the molars come much closer together. Therefore, for this reason alone, one should never touch the front. Now add what you stated in your article above, and your now have two good reasons to leave the incisors alone.

  4. Thank you for an excellent overview of this topic. I had never heard of it and my horses have their teeth done yearly. We have never done this. (We are in Canada). And I would have to say I have not heard of anyone doing it in my circle. My Sr, horses get theirs checked every 6 months. One article that you could write is about dental care for foals up to age 5. I have a Friesian mare that had limited dental care done as a yearling. I got her as a 10 year old from the states, already missing one tooth. She now has had 5 extracted and one more is loose. Her dental care as a youngster could have stopped this problem. It is unfortunate that people don’t treat horses teeth the same way they treat their own. (or maybe they do??)

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  5. Hey Doc! The notion that the incisors require any reduction is utter nonscience.As a horse harvests food(grass/hay)
    the cheek teeth are actually chewing and with the help of the tongue form a swallowable bolus.So is it possible that there is
    a slight space between the cheek teeth of the mandible and the maxilla while the food is being chewed?If so how then is there contact
    being made between the mandibular and maxillary incisors?Horses are either left sided or right sided chewers,so then
    does the imbalance of the incisors correspond with the side they chew on?Ithink not.I think that through the harvesting and
    positioning of the food into a bolus allows the tongue to strop against the incisor surfaces,so there is one of the possible
    explainations.I have seen just how sharp the medial surfaces of my horse´s canines can get and this the tongue stropping
    these surfaces.So does the tongue have the same effect on the incisors?I believe so.

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      1. Hey Doc!I thouight a little more about this rediculous notion.Ok so we don´t live in a perfect world…right!
        I have one foot slightly longer than the other.I have one arm that is also slightly longer than the other.
        I have one leg slightly longer than the other.I think most people probably experience one or all of the
        same things.So that´s life right.So if you do not like certain physical features of your body such as your
        face you can get a nose job,a chin job and so on.These are all cosmetic procedures.To me working on the
        incisors to get that perfect look,all in the name of necessity for the horse´s dental is bunk.This
        comes across as people convincing others that we need that flawless look.They just cannot accept that
        things happen,including the appearance of a horse´s incisors.Did it ever occur to these compulsive
        perfectionists that maybe some horses are cribbers or chew on stall bar partitions or doors?Most likely
        not.People who do not like the way their teeth look can improve their smile and look through many
        different procedures such as caps and so on….the bottom line is it´s cosmetic no matter how you look
        at it.There´s an old saying….if it ain´t broke don´t fix it.Whenever I have defended my beliefs on this
        non incisor reduction,there is is quite often alot of flack…..but until someone can prove the health
        benefits of this(and so far that has not happened) I will keep advocating against this.

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  6. I agree that the incisors don’t need to be touched either. Although I had a couple of horse people tell me they did because of the gap. When I asked questions they made it sound believable and they almost had me convinced. But my mind kept questioning the logic and I never had one of those dentists out. So glad that I didn’t listen to them!!

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      This is a great example of why it is important to think. In this age of marketing we are taught to believe everything we are spoon fed. And it is the belief systems that give us the foundations to live by.

      Donald Trump is the best president.
      Donald Trump is the worst president.

      Own one of these statements and then try to convince the other they are wrong. Until we personally know the truth, we are subjected to what others think. It is up to us to use our brain. How did the horse survive 55 million years of chewing without having their incisors altered?

      You might find this blog interesting on beliefs: https://theequinepractice.com/rhubarb-pie-the-orbiting-earth-and-your-horse/

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      Absolutely not. It is the opposite. It is the movement of the jaw that creates it so it is impossible for the hook to block the movement of the jaw. Think of the boat rubbing against the piling. The notch created in the wooden piling doesn’t prevent the boat from moving, rather it is the movement of the boat that creates the notch.

      Another way of looking at it is that the hook is created because the opposing tooth is NOT touching it.

As of November 2018 I will no longer reply to comments. There is just not enough time in the day! I sincerely appreciate all of your interest and am grateful for the time you take to comment here. Doc T

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