AAEP Ask the Vet: Dentistry

  1.  A local dentist, trained in the U.S., choose to file the wolf teeth down to just below gum-level in preference to the standard extraction procedure. What are the chances of infection due to exposed pulp? Wolf teeth (in my short experience) does not seem to behave in as predictable a manner as the rest of the dental family!

From the front to the back of the mouth are the incisors, canine teeth (if present), wolf teeth and a set of 3 deciduous premolars (first 3 cheek teeth), which are replaced by a set of 3 permanent premolars. Located in the deepest of the back of the mouth are the permanent molars (second three cheek teeth). All have some structural differences from each other but have basically the same functional makeup of types of cells. The clinical crown is the part of the tooth erupted from the gum and visible, the outer shell is a layer of cement, a layer of enamel (may be in exaggerated folds) and then internal cement. Within or central to the internal cement there are one or more additional rings of enamel and types of cement. And in the “middle” of the tooth there is dentin. The dentin, most central in the tooth, is formed by cells lining the blood pulp cavity. Those cells fill the cavity from the occlusal (chewing) surface towards the root of the tooth as the tooth wears, preventing pulp exposure and subsequent death of the cells located in and lining the pulp cavity. If the interior pulp cells of the tooth become infected, it is a pulp infection. If it travels up to the root, it becomes an apical root infection. There are various reactions that occur to limit infections and pulp stones and bone sclerosis are a couple that are common in horses with pulp exposure and root infections. Sometimes if the insult is relatively small, these stop the invasion of bacteria and cell death and goes no further, or the infection may spread into apical root infections and bone infections. In bone, an abcess forms (to wall off the “enemy” from the rest of the body) and may cause swelling and visible drainage of pus if there is an outlet such as into the sinus cavity, or an easy route to the outside of the body.

The healthy equine tooth is also attached to the bone socket (alveolar bone) by living ligament cells that adhere to the cement layer of the tooth and to layer of cells on the bone surface in the socket. These cells (forming Sharpey’s fibers) have a special role in herbivores that continue erupting teeth, because they are the cells that act to “crawl” the fully formed tooth out of the bone as it wears, and provide a continuous grinding surface for macerating fibrous foods. So the second place that a “tooth” infection can occur is around the inside of the socket, if the ligament holding the tooth becomes open to bacteria (such as occurs with geriatric horses when the tooth becomes short and is mechanically “wiggled”) or if a disease (such as pressure necrosis) causes the death of the ligament cells. Either way, the tooth loosens in the bone. Sometimes this is followed by the bone cortex (surface) inside the alveolar socket reacting to bacteria to form a cement-like attachment across the dead ligament to the tooth root.

The “wolf” tooth is morphologically a usually very small, vestigial (genetically disappearing) premolar tooth. Some wolf teeth are tiny and others may be large and long (2+ cm) and even have a molar like shape and may have a small blood pulp within. Some horses have one or no wolf teeth and a few have lower wolf teeth or displaced blind wolf teeth that do not erupt through the gum or sit in unexpected places like along the interdental space (bars) of the mouth. In horses older than 2 ½ years that have normally located wolf teeth (i.e. right near the second deciduous premolar tooth) the wolf tooth roots may already have been damaged by the acid bursa of the newly forming and perhaps already erupted permanent second pre-molar tooth. These may remain loose or may have sclerosis later and attach to the bone. I tend to be very cognizant of the location of the new nearby permanent tooth when removing wolf teeth that are near newly erupting, but not yet visible, permanent teeth. My goal then is to remove all the fragments of any size. If there was a question between leaving a fragment or protecting the new tooth. I opt to protect the tooth with certainty and make a note on the patient record to examine the area in a few months or next visit, removing any fragments remaining.

To finally answer the question in context, I believe the chance of an infection would depend on the size of the tooth, the age of the horse and whether a pulp is present in the tooth. I would guess that a chance of an infection of any significance would be very small.

My other thought to leave you with concerns the ligament condition over time. If the ligament allows the tooth fragment to migrate out, it may come in contact with soft tissue during riding much as the original spicule, or loosen and actually wiggle around in the gum against the bit. Since the whole reason to address wolf teeth at all is to insure a comfortable and safe bit experience for the horse and rider, purposefully leaving a fragment seems counter-intuitive to me. A small surgical procedure with an anesthetic block and the appropriate elevators and forceps is reliably very quick and simple, and without the root fragment present, the bone and gum heal amazingly fast; so… why not just remove it all? Cindy Allen, DVM, Bit O' Magic Equine, Aluchua, Fla.

 2. Can fretting from being stabled, and in muddy conditions, cause foaming and drooling?

Drooling is saliva that is either profuse release or a normal amount that is not being swallowed. 

If profuse and particularly slimy, it may be due to some type of irritation. 

If it is the type of salivation producing foaminess that is what you might see on the horse's mouth and lips when they chew on a bit continuously, thus is less indicative to me of direct mouth irritation. 

With your horse, my first examination would be to check inside the mouth making sure there is not overly sharp edges or problems with occlusion causing him to chew or irritate his cheeks. 

And secondly, to determine if  he is chewing on something - like wood or stall items - to irritate the  lips or mucosa. Thirdly, if there does not seem to be other obvious reasons why he would be drooling so much, I may want to consider ulcers as a possibility.  

With a stalled horse that is fretting regularly, stomach ulcers can be present. 

One theory associated with "ulcer" behavior in horses is increased pain from the lesions occurs as acid is released when eating a grain meal or when fretting. Ptyalism (constant grinding of teeth) is a reaction associated with ulcers in young horses. Chewing in general causes a saliva release in all horses, and calcium containing saliva actually has a buffering effect in the stomach. 

The surest way to diagnose ulcers is with a thorough endoscopic examination, which will include the stomach and upper dueodenum in the horse. 

If diagnosed with ulcers, the problem will usually respond well to term of 4-6 weeks of appropriate oral medication with omeprazole or ranitidine coupled with management changes such as more turnout and regular access throughout the day to grazing or access to forage. Cindy Allen, DVM, Bit O' Magic Equine, Aluchua, Fla.

3.  I have a Quarter horse mare, approximatley 20 to 25-years-old. She is pasture kept with another Quarter horse 24/7. She was last dewormed in November. It has been a harsh cold winter, but she kept her weight really well as she and her buddy had shelter and blankets. They share a trough, which I fill with 8-10 flakes of hay for them. My horse is boss, so I know she is not being chased from the food. I also give her half a 3qt scoop of sweet feed in the morning and again in the evening. In January, I noticed she began quidding and her weight began slowly dropping, so I had her teeth done. Since then, she has been eating better, though I believe, with smaller mouthfuls, and a little less gusto than at the start of winter. She does not look too thin at first appearance, but she has a thick winter coat, and her weight has decreased. I can easily feel her ribs, which has me worried. Am I feeding enough? Should I increase hay, grain, or both? She did really well with this feeding schedule throughout the winter, but am trying to figure out what has changed.

With reference to an older horse that has had some signs of dental insufficiency and weight loss, l will address some dental information first and then some suggestions for feeding the older equine.  This is a general discussion, and I would suggest you consult for your mare and her health specifically with your trusted veterinarian.

Quidding is rolling the hay rather than cutting it when chewing and usually spitting it out uneaten. With adequate grinding ability the horse will move hay into the front cheek teeth and grind and then move it from cheek to tongue and onto the next teeth a bit farther back and repeat…each grind should result in shorter and shorter pieces of hay until it is macerated into very tiny particles at the back teeth and is in a homogenous bolus and swallowed. Horses that can move the jaw with enough motion but that cannot make contact to cut the hay with their teeth form a twisted “rope” of hay. There is other dysfunctional chewing that may form pads or lumps of hay and horses may actually be swallowing these even though they are not well chewed. A good way to get an idea of chewing efficiency is to inspect manure for hay and whole grains. Normally there is not much, if any, recognizable hay and no whole grains visible.

Diarrhea can be caused by other illnesses and by sand, or by diet changes made too quickly… but I see some cases in older horses where it is actually caused by undigested food molecules in the large intestine drawing water in and causing intermittent diarrhea.  Large particles of food are not conducive to attack by the flora and it does not provide for normal proliferation of flora. Once the particle size is corrected the micro-flora population usually returns quickly in a few days, and the diarrhea abates. This can be as simple as adding hay pellets or senior food to their diet. The population of intestinal micro flora forms a significant source of protein for the horse.

Equine teeth are formed and erupt into the mouth from before birth into the fourth year (canines a bit later). Cheek teeth continue to lengthen in the maxilla and mandible until around eight years old and from that point on they simply erupt as they are worn off, until only a short root section of tooth is remaining. Sometimes these may fall out or they can partially loosen and roll into the cheek or break into pieces.

In my experience horses into the mid to late twenties on average, begin to lose their ability to erupt any more tooth length. It is never all the teeth at once so the problem with chewing may be compounded by uneven attrition and wear, waves, steps, slants  and the result is chewing  just slowly becomes less efficient, and the jaw muscles will reflect this with visible atrophy. Shortening and leveling the incisors (front teeth) regularly is important as well, particularly in older horses, since they may have longer incisors and shorter (worn) cheek teeth.   

Even though your mare is now chewing well enough to no longer quid, it may be that her teeth are worn so that she will need pelleted food to provide her with enough hay calories. If you feel she may be uncomfortable, a speculum exam to look for fractured or loosened teeth due to wear is appropriate.

There are many good ways to design a senior diet. The goal is a diet that; meets the basics for nutrition and leaves the horse with something to “graze” food or grass throughout most of the day and night, provides food of a “digestable” particle size, and is a diet that works for your management scheme. Each situation has a lot of factors that may play into what will work best, such as: 

* Pasture companions

* Hay availability

* Where, in the range of tooth attrition your older horse actually is, can they eat some grass but not hay?

* How easy of a keeper are they?  

There is also an array of major food manufacturer websites that have articles about special nutrition, such as low glycemic index foods and higher fat foods, feed calculators online, and the larger companies employ highly educated nutritionists and veterinarians that may provide information and support for owners and veterinarians for consultation about their products.  

Additionally, some health issues can cause loss of muscle mass -PPID (Equine Cushing’s) and abnormal fat distribution –EMS (Equine Metabolic Syndrome). Advanced PPID can be the cause of unnaturally curly or long hair coats and contribute to Insulin dis-regulation these statistically become more prevalent in the older population of horses. There are many foods available in pelleted “senior” form for special health issues so if you have a horse with health issues work with your vet to find the right one for your older horse.

  1. Always make changes slowly over 10-14 days, this allows time for the micro-flora to adapt to new food.
  2. A kitchen food scale is important, every food has a different weight per scoop, and feeding directions is likely in pounds.
  3. Calculate adequate calorie intake to maintain weight. These calories come as… concentrates, forage, pasture and ration balancers. If a horse cannot chew the needed amount of forage then a senior food may be appropriate.  Senior food is usually a “complete” food. This indicates that there is both concentrate and hay both and the food is formulated with sufficient fiber to provide a minimum of “forage” even if no additional hay is fed.  The recommended feeding rate is much larger than the regular concentrate food.  This makes sense since it contains “hay” as well as the concentrate.  Senior foods have amounts for feeding alone or with a minimum recommended amount of hay, so read the bag for each food.

They also have a minimum amount by weight listed that must be fed to “balance” the diet, Usually it is about 6 lbs /1000 lb BW and would require a lot of hay additionally to support a 1000 lb horse…so this means a scoop of senior will not provide the necessary vitamins and amino acids for a balanced diet unless you are feeding a mini!

  1. Forage- all horses need fiber in adequate amounts, usually 1.5-2.0 % of BW, with 1.5% as a minimum for healthy gut function, which includes gut flora.  For example, a 1000 lb horse needs around 15 pounds a day (minimum) of some type of hay; flakes, chopped forage, or pelleted forage.

How do you decide which form? The one they can chew well or pellets! If they are sorting stems out of hay, quidding, or just leaving hay, but eating easier to chew foods, then they probably need pelleted hay and /or a “complete” food. If still eating some hay, but not keeping weight they may be able to eat a moderate amount of senior food and continue to eat hay.  

Hay cubes are not equal to pellets, when soaked they still have a large percentage of 1-2” stems that needs to be chewed in order to be utilized. Remember, wet food to a soft consistency if your horse may gulp it.

There are two big advantages to adding Senior or hay pellets into the diet even if your horse can still chew some hay.

1-      A risk for colic is likely greatly reduced by mixing in some small particle foods.

2-      The small particles will allow a normal population of flora to proliferate. This increases the protein available from hay and fibers for digestion.

For example: 1000 lb horse …generally was an easy keeper until his teeth became worn.

He use to eat 3 lbs of concentrate food, 15 lbs of grass hay and one small pad of alfalfa per day split into 2 meals and had a paddock of short grass to graze between meals (20 lbs of forage total).

Now he has trouble with hay stems and leaves them, he has a few intermittent bouts of loose manure now and then (his veterinarian finds him healthy) but he has a lot of visible hay and oats from the concentrate in his manure…

 Now he will eat…

6 lbs of a “Complete” and “Balanced” Senior food, 10 lbs of timothy pellets, and 3 lbs of Alfalfa pellets and grass (since he can still nip and chew some soft fresh grass at pasture).

I figure about half the weight of the senior complete food as a portion of the daily “hay” ration, and the wetted hay pellets will replace his hay that he can no longer chew. He goes back to being an easy keeper.

Or… for a very senior horse that is a hard keeper and cannot chew even grass anymore…

15 lbs of Senior (based on the ideal body weight and the feeding amounts given by the manufacturer).  Always divide meals so less than 5 lbs per meal is fed for a 1000 lb horse. The more meals you can manage thru the day the better for the horse and the more you will stretch your food dollars, because they will likely get more energy out of the same food if eaten slowly in smaller meals. Large meals tends to cause the stomach to empty prematurely.

  1. horse specific mineral balancer and free choice salt, is recommended by most all feed companies in addition to their foods.  Since balanced foods contain the minimum of daily required minerals for all horses, it is adequate only if the animal; isn’t sweating a lot, isn’t ridden a lot, isn’t stressed...etc.  Extra needed minerals, is made up by what you provide beyond the balanced food. I personally use loose minerals and loose salt in separate feeder tubs in my run in barns, loose salt is especially nice for older horses since their incisors may not be as comfortable as they used to be so, they may not get enough on hot days just licking a block. Red salt/ trace mineral blocks are just that- mostly salt and not equal to providing a “real” mineral balancer.

For me free choice usually works best, because most animals are very good self-regulators when it comes to salt and minerals, but always limit it until you see how much your horse will eat.

If necessary, dole out a few tablespoons or ¼ cup a day for a full sized horse until the novelty has worn off and they are satisfied.

I personally stay away from adding electrolytes or minerals right into food. This is the equivalent of “force feeding”; most animals will eat the food regardless, and it is rare that a healthy horse not in extreme work needs electrolytes daily. Electrolytes can dehydrate your horse if overfed.

Senior horse notes…

  • Choking is a possibility for any horse not chewing food well. If you aren’t sure that your senior horse will be able to chew dry pellets with the tooth he has remaining or if any horse tends to eat big mouthfuls too fast, then covering the pellets with water at feeding time to make a wet oatmeal is a good idea. “Soupier” is usually hard for them to eat.
  • I find that timothy hay pellets are not nearly as “good” to most horses than senior food or alfalfa pellets…so you can use them separately in a pan (wet if need be) for a pasture food that will be eaten slowly. For example…I feed regular hay to my younger horse and a pan of wet timothy pellets to my geriatric (he is 31) in the same pasture and it works well. My younger horse prefers hay and my older guy can’t chew hay. I separate them at “feeding” time twice a day, so my senior can eat his 4 lbs of senior food  and 1 lb of alfalfa pellets slowly during those meals and not get robbed.
  • Management usually consists of figuring out how to leave the senior with a buddy nearby…for grooming over a fence or sleeping, but allowing them plenty of separate time with their food so they can eat slowly.
  • Try not to leave long periods without chewable food to “graze” on.
  • Be cognizant if wetting food that it can sour quickly and if the horse is not eating it –then it may be soured. This is especially true in hot weather. 
  • Senior horses usually require extra protein so most senior foods are a bit higher in protein 12-14%.
  • Look up and learn to judge your horse’s condition by using an Equine body condition scoring system, and use a weight tape to track trends. Try to have your horse gain less than 1/2 pound per day if gaining weight back.
  • Don’t discount the possibility of PPID in older horses, it is statistically very prevalent in horses by their mid-twenties and treatment to control the symptoms can greatly increase your horse’s longevity and quality of life. Talk to your veterinarian sooner rather than later, if you suspect your horse may be affected by PPID. Cindy Allen, DVM, Bit O' Magic Equine, Aluchua, Fla.

4.  My dental question is in regards to EOTRH in a severe parrot mouthed horse. In your research or clinic, do you have knowledge of a horse(s) with severe parrot mouth, where there is complete loss of incisor contact, to be off feed due to EOTRH?

In my understanding of where we are in current research, the pathology of EORTH is now thought to be caused by pressure necrosis of the alveolar ligament. With constant pressure on any single or multiple incisor/s or the first premolar the tooth structure below the alveolar rim places pressure on portions of the thin living alveolar ligament. This ligament is a living tissue requiring circulation to remain as a viable connection between the cement layer of the tooth and the alveolar bone. The bone can remodel under pressure but the tooth is an already mature and solidified structure that does not allow for significant remodeling in the healthy tooth. Thus the living ligament selectively dies and becomes necrotic within the socket. This produces one or more of several clinical clues upon examination such as:

1. necrotic draining pustules breaking through the gum at level of the alveolar rim margin above the gingival attachment, these “bumps” drain pus when gently opened.

 2. The affected tooth starts loosening- with resulting food packing due to motion seen between teeth and significant discomfort during grinding of the tooth or hand rasping.

3. With prolonged infections, eventual sclerosis and a direct bony attachment may form between portions of the tooth and the alveolar bone.

4. With a loosening ligamentous attachment the root sometimes becomes prolific, with layers of bulbous cementation (an attempt by the body to solidify a moving tooth in the bony socket or an inflammatory reaction to the process) and subsequent remodeling and enlargement of the visible shape of the bone surrounding that root.So this would infer that any tooth that has severe unnatural pressure can develop the disease, and secondarily if it is present EORTH is almost always painful to the horse in my experience. 

Clinically, I have not personally seen a case of either maxillary or mandibular prognathism with diagnosed EORTH present, but our knowledge of the pathology would infer that if pressure contact with the bony palate is severe on the lower incisors, or bio-mechanical pressure during mastication caused by the lower incisors trapped behind the upper incisors severe, then over time ligament necrosis is possible.

In any case, start by clinical examination of the length and positioning of the teeth and the surrounding gums and bone and a thorough whole mouth exam and balancing if indicated to rule out other possible obstruction and imbalance issues causing discomfort (horses with conformational malocclusion of the incisors may or may not have properly conformed and opposing upper and lower cheek teeth). If the restriction due to trapped teeth or large hooks or waves is severe, I have seen horses lose a normal interest in food due to pain without disease present yet. Secondly, if EORTH is suspected, obtain a set of radiographic views of each arcade with good resolution and delineating the alveolar ligaments, or lack thereof.  Separate radiographic views of each of the arcades can be readily obtained by open mouth DV and VD views, utilizing a protective tunnel for the digital plate or a set of two 3” long plastic wedges placed in each side of the cheek arcades and in a sedated horse. (It is important to know that teeth are fairly well smoothed and do not have large waves present to preclude damage if imbedding hooks or pressuring high cheek teeth when the horse chews against the wedges.) Adding a slightly oblique view can sometimes allow visualizing the root in a different plane if pathology is questionable in the lower corner incisor teeth.

If EORTH is diagnosed, or an unresolvable obstruction by offending teeth is present, it should likely proceed to a discussion between your equine dental specialist and yourself to weigh the benefits vs. the  problems presented by surgically removing diseased incisor teeth to resolve the EORTH discomfort and prevent damage to the palate. If palatal trauma or entrapment of the arcades is severe enough then extraction to correct mechanically induced pain may be warranted, keeping in mind that if only some of the lower teeth are removed it may increase palate trauma or mechanical pressure by or on the remaining teeth. 

A few of my cases have involved stoic horses whose problems were not noticeable to their owners, but who showed extreme sensitivity to dental prophylaxis on incisors. These were diagnosed using radiographs and subsequently after extractions made a noticeable improvement in mastication and attitude per their owners. So the signs of EORTH in behavior changes is not always clear in EORTH cases, especially if the horses attitude has changed slowly.  As you are likely already aware, a complete turn around in patient wellness becomes apparent in most cases after extraction of all the painful teeth, with horses happily eating all their  grain and hay shortly after the teeth are out. Nipping short grass is, of course, not possible for horses without any front teeth opposing, but for a severe overbite as you describe, there may already be an inability to graze normally. I have noticed that most horses do hang their tongue out a small amount when relaxed if all of the upper teeth are removed.

As a general note;

In managing my cases of non contacting incisor arcades due to maxillary prognathism; regular (2-4 times) yearly grinding of the incisors combined with careful balancing of the cheek teeth may aid in reduction of the palatal trauma over time, and may check rampant caudally curving overgrowth of the upper incisors for some horses, particularly if started early in life. Of course, caution must be practiced at each prophylaxis to protect the vital pulp of the incisors, while doing as much shortening as possible. I have also found that preservation of the height of the lower rostral cheek teeth arcades; the proximal to distal rise of the 300 and 400 arcades to the 306 and 406 teeth and the same of the maxillary teeth, (within normal functional TMJ balance, i.e. not too drastic of a rise), is helpful in providing distance under the palate and managing the incidence of palatal trauma over the long term. Cindy Allen, DVM, Bit O' Magic Equine, Aluchua, Fla.

 5. My horse has a severe parrot mouth. Floating to remove the hooks/ramps is done twice a year but the incisors have been left untouched for more than two years. The top incisors don’t make contact with anything and the bottom incisors make contact with the palate. How do you know when it is time to have their incisors reduced in length? There aren’t any visible sores on the palate but weight loss and shaking the head have become an issue.

It would be difficult for me to give you a specific opinion, without first doing an exam to determine the ability for your horse to touch the cheek teeth for grinding, and the extent of the interference of the incisors. Working on the teeth myself would aloe me to determine how much I would be comfortable removing if shortening is necessary.  So please consider this a general discussion of the obstacles I may consider and a few of the techniques that I might use for a case of severe maxillary prognathism  (parrot mouthed) horse, not necessarily my recommendations for your horse.   Formulating and monitoring a plan for their care can be challenging. The amount of work and accuracy of the work needed lends itself to using electric grinding burrs rather than hand tools for me, but that is a personal preference and although most dental focused practitioners have these tools available incisor work can be done without them.  There are some, rarer yet, cases that cannot be kept functional or comfortable by dental maintenance and then a surgical removal of some or all of the incisors may be a consideration. This is only a decision I would make in severe cases where shortening has failed to be successful and the horse is unable to be made comfortable to eat.

There are also other health issues that may cause what you describe, so I would be remiss if I did not encourage you to have a thorough examination done first with your local veterinarian to rule out other health issues.

Generally starting early in life for this type of malocclusion (as soon as the teeth are beginning to over grow) and likely planning on maximum shortening work 2-4 times yearly on the incisors, while attempting to preserve much of the normal length of the cheek teeth through very conservative work will allow for the best clearance of the lower teeth from the palate and the upper and lower incisors from each other.  Palate contact forms a hardened callous on the palate directly behind the upper incisors where the teeth are pressing against it. Sometimes the interference to normal chewing occurs by the overlapping contact of the incisor teeth themselves with each other. This can be recognized by checking grinding ability carefully through grasping the upper and lower face and moving a relaxed jaw in the chewing motion. Either way, shortening the incisors as much as feasible is usually helpful. Even if the overlap is partial with a bit of incisor occlusion at the corners (03’s) the incisor arcades still need to be level from left to right across the entire set of teeth so that both the  side to side and slight front to back “orbital” motion during chewing is not impinged. If the incisors are longer than normal and occluding at all then they are likely affecting the grind of the cheek teeth.

When starting on an older horse where the incisor length has gotten ahead of a shortening plan I do try to accomplish as much shortening as I consider feasible each visit to make headway, and I would want to see the horse a few times yearly so that there is  3-4 months between visits for the pulp cavity to fill with tertiary dentin for protection, but not so much time that headway in progressively shortening the incisors is lost. I would caution that when I am attempting to do a maximum amount of work on any teeth I almost never actually go by a set measurement of length to remove, because it can be very variable among different teeth and different breeds and ages of horses. Making an assumption that you can remove a set amount may give unexpected results if teeth are shortened quickly assuming you have a “safe” amount of tooth to remove.  I keep an idea in mind of how much my general goal is, but my guide is to watch each tooth carefully for subtle color changes during shortening and to work very slowly. This gives me the best opportunity to do a good amount of work for the horse at each visit but to know when I want to stop shortening and put off additional work for another visit.

 I have seen quite a few horses over the years with incisor trauma from kicks and trailer bumps, fights and collisions with stationary objects, causing a fracture with a severely opened incisor pulp and/or deeply fragmented incisors and a large percentage of these create a pulp stone that plugs the pulp cavity and prevents a root infection on their own.  Cheek teeth fractures tend to not be as forgiving; the roots are multiple and branched and infections from fractures are common.  So I am even more likely to stop work earlier to protect the cheek teeth from accidentally touching a pulp tip.  For teeth that are preventing proper chewing I try to be as aggressive as possible to bring them back to proper occlusion but stop to protect pulp if in doubt. The age of the horse also contributes to the decision of how much shortening I am comfortable to do, young incisor teeth that still have the shelly cusps can usually be shortened quite a bit while working on the edges around the “cup” but as soon as the initial edge is removed, young teeth may have a large pulp closer to the surface than older teeth.

Since the pulp of the teeth may dictate when you have to stop shortening, or you may know when starting work that you will not be doing as much shortening as you wish in a single visit, I work mostly on the longest teeth first to bring them into level and then continue shortening equally so the arcade is as level as possible when I stop.  Level and free lateral movement of the mandible is dictated to a great extent by the path of the incisors which allows normal function for the occlusion or grinding ability of normal balanced cheek teeth and provides for normal apposition of the surfaces of the TMJ. My goal is primarily to relieve incisor trauma to the palate and interference with the other teeth, while keeping in mind that a pulp cavity can be opened from the side of a tooth as well as from the bottom of the tooth.

With respect to the joint and dental imbalances and restrictions… many important facial and proprioceptive nerves, both motor and sensory types of nerves, pass near or within the fascia associated with the TMJ and protecting or improving proper grinding ability allows the least abnormality to the joint function and improves many clinical signs that may be associated with joint nerve irritation or joint soreness directly. While I would agree that perfecting teeth cannot fix all maladies… there are a surprising number of problems that may be associated with imbalances of the teeth,  such as;  head tossing, bucket flinging at meals, disagreeable attitudes about bitting or having ears and face handled, sensitivity at the poll with increased resistance to haltering and tying, all the way up to problems resisting collection and/or flexion in work, resulting in heaviness riding,  stopping at jumps, stiffness in turns…etc… etc, and of course obvious problems eating such a quidding hay, dropping grain and inappetance if uncomfortable to the extreme.  The solution for many horses is to free the restrictions to normal jaw motion while correcting the angles and overall ease of contact of the cheek arcades. This does not necessarily mean the teeth are “smooth” to the extreme.  I am a proponent of conservative smoothing when necessary, but occlusal surface interface angle and quality grind that does not require abnormal lateral motion is by far more important in my opinion.  Over aggressive smoothing with a significant amount of enamel removal may cause accelerated wear beyond the capacity of the horse to erupt replacement crown length.  If cheek teeth are shortened by accelerated wear to the point of not supporting the grinding cycle then TMJ discomfort and the horse’s purposeful disuse of the chewing muscles will likely follow in my experience. Atrophy of those muscle groups can be seen easily in many of these cases.

 With all that said… the balance for the cheek teeth, as well as the height of the overall arcades and angle of the surfaces that occlude must be kept very close to as normal as possible,  because a severe “uphill”  lower  arcade or significantly “long” upper front cheek teeth may “help” by holding the incisors apart; but abnormal heights of some of the teeth in the cheek arcades may also cause uneven wear of the back teeth due to abnormal pressure and problems chewing but also improper opposition of the TMJ’s. This then becomes a factor in my opinion of a host of other secondary problems such as: irritability with the face or ears being handled, poor bit acceptance and contact, poor collection or flexion, habits during eating such as bucket flinging or head tossing, as well as, long term abnormal inter-articular cartilage wear, abnormal forces on the meniscus within the joint and accelerated arthritic changes of the joint. 

So… I would suggest seeking a physical exam, a dental exam and start on needed corrections.  In the short term you may want to consider feeding as you would an old horse with dental problems chewing, so wet hay pellets (not cubes), the consistency of oatmeal to replace some of the hay (by dry weight). And consider a senior or senior low starch, complete food, as appropriate.   If your horse is older with a possibility of PPID, or you know your horse has special health issues it is particularly important that you seek veterinary advice for a diet change.  Using the feeding instructions for the food you choose is important as well. Researching diets for horse with problems grinding food may give you some insight for diet and management. Just a change to hay pellets may drastically increase absorbable calories if there was a previous problem grinding hay. Remember to make any changes to diet slowly over 7-10 days and make increases of absorbable calories slowly as well. Cindy Allen, DVM, Bit O' Magic Equine, Aluchua, Fla.

6. This morning, one of the horses I care for had swelling across the bridge of her nose where the halter rests. The owner has recently hired a new farm hand that uses negative reinforcement. He was working with her yesterday, could he have jerked forcefully enough to injure the bridge of her nose or should I be looking for a different cause? I attempted to palpate for possible fracture but the area is too edematous. He had made the comment about teaching her to back up and I wonder if jerking back on her halter would cause bruising or fracture that could be the source of the swelling.

I am sure that it is possible to bruise tissue across the bridge of the nose or even fracture the incisive bone if enough force is used. However without being present to examine your specific horse I would not speak to this situation in particular. I would strongly suggest an examination in person w your owner's local trusted veterinarian to help determine what needs to be done for this horse if swelling is persistent.

As far as equine nose and facial injuries in general.... 

For any horse with swelling that appears to involve the incisive bone or cartilage, I would likely want to have a set of radiographs to confirm the soundness of the bone before placing any stress on the incisor teeth through the use of a speculum.

It is important to determine if edema is caused by injury to the soft tissue vs bone vs cartilage; or if it is even just a skin irritation due to a reaction from leather or tack cleaner or soaps or even plant particles that may stick on the inside of a soft halter. After external examination, depending on where the swelling and sensitivity is,  I might also include an intra-oral examination of the cheeks and teeth and/or a look into the nostrils.

In case you are interested in some general equine facial anatomy:

The dorsal (upper) area of the equine nose is an outer shell of bone which houses the rostral (forward) and caudal (towards the ears) maxillary sinuses, and the conchal dorsal sinuses: These are air filled sinuses that are above the nasal canals (where the horse actually breathes in) . Some of the upper cheek teeth actually sit under the floor of these and the nasal lacrimal ducts (drain tears) are housed in bone nearby and flow out the end of the nose. Part of the sinuses also house a fairly fragile bony canal running through them that protects a major nerve for sensory function to the entire bone of the upper face. The (conchal) dorsal sinuses are in the center of the nose just under the "bridge" of bone and run lengthwise down most of the upper half of the nose from low forehead level.

The lower structure of the "bridge"  of the nose is made up of bone and cartilage with a relatively fragile area where the incisive bone gives way to the continuation of the cartilage of the nasal septum. This septum divides the the nostrils; right and left and rounds to form the nares or nostrils and nose structurally. This cartilage can be located anatomically via palpating in the normal horse by gently grasping low on the bridge of the nose and wiggling left and right to feel where the points of the incisive bone ends and the cartilage begins. This area is lower than the proper place that a well adjusted halter or over the nose chain should rest. Cindy Allen, DVM, Bit O' Magic Equine, Aluchua, Fla.

7. Why do veterinarians not routinely address the front teeth when floating? If there are obvious points, etc., should these not be addressed as opposed to "allowin them to wear naturally?" If the teeth wore naturally/correctly, there would be no need to float, right? Doesn't floating the back without addressing the fronts leave the mouth unbalanced?

This is a most valid concern in my opinion. It is a complicated discussion so let me use your questions, as you have asked them, to address the issue as I see it.

Why do vets not routinely address floating the front teeth…?

This has several suppositions so let me start by saying that I am a veterinarian and I rarely touch a horse for dental work, which does not get at least some attention, to leveling or shortening or even just smoothing baby’s shelly new front teeth before placing the incisors in a speculum for work in the back. Placing a speculum plate on uneven young incisor teeth is asking to fracture chips off and placing it on very un-level or diagonal teeth is asking to fracture a root on a tall lower corner tooth… not to mention the stress that is transferred back to the TMJ if teeth are uneven and the speculum cannot be opened symmetrically.

I have also followed behind many non-vets who have floated but ignored incisor length and balance, so it seems to be more a question of why this isn’t addressed across the board.

 …if there are obvious points…etc. should these not be addressed?

Again in my experience I would say  emphatically “yes”  they should be addressed… but in addition to addressing the obvious details such as hooked corner incisors or small points, I would add to that and say that the ratio of upper incisor length to lower incisor length and the levelness of the incisors from left to right is even more important  to the proper biomechanical angle and stresses placed on the TMJ,  as well as the angle of incisor teeth overall  with respect to the center incisor (101/201) intersection)  and the TMJ is critical in determining if the horse will not only be comfortable eating, but if the horse will create or, continue to create a depression at the lower 10’s (next to last tooth) and be predisposed to forming  caudal 311 and 411 hooks. (last lower teeth on the left and right)

If anyone practicing equine dentistry has doubts of this try an experiment-  mirror this discussion by accurately and levelly grinding these angle changes on the incisors of a cleaned skull and watch the geometry changes  and forces created at the molars and at the interface of the joint surfaces of the TMJ by increasing the angle of the incisors more and less acutely.  If you really want to become a believer of how detrimental poor incisor balance is to the horse use a filler of thin foam to imitate the TMJ meniscus and use dental marking paper between both sides of the foam to mark the inter-articular forces and look at the pressure points created on the inter-articular protuberances by these changes.

…Should front teeth be allowed to wear “naturally” ?...

I have an eclectic (but somewhat scientific) conclusion about that…I think it makes sense that our domesticated horses these days do not eat from hardscrabble grass areas and pick thru all the rough vegetation that most wild horses must to survive. The domestic horse also has a life span 2-3 times that of most “wild” horses… so I believe they are not wearing enough naturally, given the history of the horse’s  recent (genetically “recent”) living conditions, especially as the horse ages. I have also come to a general opinion, through paying close attention to many of my own populations of patients, that genetic populations that come from areas of the world with softer grasses  (Welsh ponies for example) have smaller incisors for their skull mass than the average horse population.  I see these horses also needing less reduction to maintain what I consider “proper” incisor length and angle.

And lastly you ask … doesn’t floating the back without floating the front leave the mouth unbalanced?

You can probably guess by now that I think it most certainly does cause unbalances in most patients.  For many reasons… eating (grinding) ability or more accurately lack thereof in horses with overly long incisors, riding comfort and normal head carriage during collection via the mandibular positioning,  and TMJ health over the long term (think arthritis and meniscal damage) and comfort of the joint during chewing  (I believe this last point can be reasoned even to the point of comparing muscle atrophy of the muscles of mastication in horses with clinical signs of TMJ sensitivity and correlating those two observations with overall incisor length, upper to lower incisor ratio, angle and left to right levelness.  We even now suspect that a disease that is prevalent in older incisor teeth (EOTRH) is caused by increased pressure on incisor tooth ligaments. This then eventually causes ligament death and necrosis due to inter-alveolar pressure. (see my answer to this month’s first question . It is a nagging question of mine concerning disease (which has been proven by research to be more common in certain populations of Western European Warmblood horses) is partially driven by floating thecheek teeth  without appropriately shortening the front teeth.

And so you ask why aren’t we all in agreement? … 

I think we are just coming into the era of attention and care that teeth and dental balancing deserve for our equine. The newly formed  College of Equine Dental Veterinary Diplomats have now recognized that incisor correction is a part of a thorough examination and prophylaxis in the recent paper written to outline expectations for a thorough dental exam and float. Up until a couple of years ago Equine Dentistry was lumped into the same Board specialty as Small Animal Dentistry.  We are seeing the slow maturation right now of Equine Veterinary Dentistry as a Board Specialty. There are some doctors across the country who have devoted a lifetime to this already and are our “gurus” but I hope that many more doctors (both general Veterinarians and Boarded Dental Specialists) will not only pay attention to the surgery and medicine skills but will come to believe as I do that meticulous balance makes a life changing difference to our patients.  Comfort, joint health and good chewing function affect horses hourly, daily, yearly and on a lifetime basis, most would agree to those premises …now we just need to mature our knowledge to point of more general and accurate consensus among veterinarians, and specialist technicians who are working with veterinarians, on how the actual art and science of balancing should be standardized. Cindy Allen, DVM, Bit O' Magic Equine, Aluchua, Fla.