Dentistry Part 4: Periodontal Disease

At last! The day's work is done and you are free to enjoy some time with your horse. There is a spring in your step as you gather up your barn gear. You slice a crisp red apple for your pal and suddenly realize that in your rush to get to the barn you forgot to eat lunch! Your buddy won't mind, surely, if you share a bit of his apple. Just as you thought ... it's delicious! But oh no! A chunk of apple has lodged itself between two of your teeth, right at the gum line--Yeowch! All the way to the barn you work away with your tongue at what feels like the entire piece of apple that you ate, but it remains stubbornly embedded in a most uncomfortable place. Once at the barn you rifle through your brush box for what you hope is still buried there. Yeah! The roll of dental floss used to repair something or other ... and bingo! You dislodge the offending fruit (not the size of a chicken wing, as it turns out) and feel immediate relief.

Now picture your horse's teeth. If you have ever been lucky enough to get a good look into a horse's mouth, you were impressed, at the least, and more likely in awe. As you know from the first articles in this series, adult horses have anywhere from 36 to 44 teeth, depending on gender and the presence or absence of wolf teeth. Of those, 24 teeth are premolars and molars, collectively known as "cheek teeth." They, along with the incisors (those teeth readily seen as your horse yawns, grabs treats, or--heaven forbid--cribs), make up those teeth involved in the gathering and processing of feed. And let's face it, although we would like to think that our horses spend most of their days pining away for us, the truth of the matter is that they will, if given free access, spend up to 16 hours per day grazing.

Now remember your bit of apple. Imagine having to go on eating without first removing something caught between your teeth. You would begin to alter how you chewed to avoid the painful spot. Your gum would become inflamed and bleed easily. More food would be packed into this vulnerable area and calculus (a calcium salt concretion) would begin to form on the surrounding teeth. You get the idea.

It is not as though your horse can floss, show you that he is packing feed between his teeth, or eat soup for a few days until the dentist can see him. He must continue to eat hay, grass, grain, etc., and do his best in the face of any dental pain.

What's Peridontal Disease?

Periodontal disease is one of the most painful conditions that can occur in the horse's mouth. The number one cause of premature tooth loss in adult horses (as in adult people) is periodontal disease. Periodontal disease can affect incisors, canine teeth, and cheek teeth.

So what defines equine periodontal disease? Equine teeth constantly erupt over the course of the horse's life, and the tissues surrounding the teeth undergo normal changes as this eruption takes place. The periodontium consists of the gingiva (gum), alveolar bone (the socket in which the tooth sits), periodontal ligament (which anchors the tooth in the socket), and the outer layer or cementum of the tooth. With normal mastication (chewing), the mouth of the horse is fairly self-cleaning; feed and calculi do not accumulate on and around the teeth. This is due to the work of normal host defenses such as saliva, white blood cells, antibodies, and "good" bacteria that are present in just the right numbers under the right conditions.

A disruption in these defense mechanisms will result in an opportunistic infection.

Salivary secretions normally function to clean the horse's mouth as it eats. Domestic feeding practices and processed feeds often lead to abnormal mastication and decreased saliva production. Decreased range of motion in the chewing cycle, malocclusions (misalignment) of the cheek teeth and/or the incisors, and trapped food material can lead to a deleterious environment within the mouth.

Normally, the lack of spaces between horses' teeth prevents feed from becoming trapped and collecting. Developmental abnormalities resulting in malpositioned teeth, malocclusions, and uneven pressures on teeth can create increased spaces between teeth and misalignment of the teeth, setting the stage for periodontal disease.

Feed packing in between or around the teeth undergoes decay and bacterial fermentation. This process and the resulting byproducts cause a breakdown of the periodontium. The gum begins to recede and forms a pocket. The pocket remains full of feed that continues to ferment and break down, gradually destroying the vital structures of the tooth or teeth involved, with the disease progressing towards the root. As the periodontal ligament is destroyed, the tooth becomes loose in the socket, and tooth loss is nearly inevitable. The horse will have long ago altered its mastication to avoid the painful area(s), exacerbating other existing dental problems.

As the disease progresses and the infection migrates along the length of the tooth, an apical (around the root) abscess could occur. Abscesses involving some upper cheek teeth can lead to infection of the sinuses and a malodorous nasal discharge. Periodontal disease can cause blood-borne bacterial infection of other body systems (such as the heart) as blood and bacteria mix in the mouth. Some systemic diseases such as Cushing's syndrome can worsen periodontal disease and alter the outcome of treatment.

How to Recognize It

Recognition of equine periodontal disease is the first step to successful treatment. It is very difficult for an owner to identify periodontal disease. Signs might include halitosis, dropping feed, weight loss, and performance problems. Or signs might be as subtle as "just not right" or mildly depressed. Many horses do not exhibit outward signs.

A thorough oral exam using specialized equipment is necessary. Even the cursory exam often performed during routine floating is inadequate. In order to give your horse a thorough oral exam, your veterinarian will need to sedate your horse, place a full-mouth speculum, and use a bright light, mirror, and a periodontal probe. Any foul odor from the nose or mouth is abnormal and should be investigated. The feed present in the mouth should be rinsed out in order to determine if and where any feed material is trapped. Your vet will then be able to look for debris or feed material collecting between or around the teeth.

Gingival recession and bleeding tissues can be observed, as well as any abrasions to the gums from rough feed material or foreign objects such as twigs or briars.

Feed will have a tendency to collect around damaged teeth, retained cap roots, or the caps themselves before they are shed. Periodontal disease is generally a transient problem in young horses as deciduous teeth are shed, but it can be severely painful and cause difficulty eating in the case of a young horse with malpositioned teeth. It is much more common in older horses due to neglect of long-standing malocclusions and age-related changes in size and position of teeth.

Overgrowths of the teeth, hooks, waves, ramps, points, etc. can cause abnormal feed accumulation between or around teeth. Spaces between teeth, rotated teeth, or crowded teeth will tend to collect feed material. Calculus often forms on the canine teeth, incisors, and in abnormal spaces between the cheek teeth, and it can lead to periodontal disease.

Your vet will use a long dental mirror to adequately view all areas of your horse's mouth. The periodontal probe is used to probe any suspicious areas and measure the depth of pockets. Any areas of trapped feed or periodontal pocketing should be noted on your horse's dental chart in order to follow the progression of healing during subsequent treatment. The integrity of the teeth and surrounding tissues might be evaluated using radiographs. Intraoral radiographs are especially useful to evaluate periodontal structures. Your veterinarian might wish to take radiographs to determine the extent of the disease and determine if it is treatable, or if possibly an extraction is indicated.

Treatment Step 1

The first and arguably the most important step when treating equine periodontal disease is the correction of any malocclusions or overgrowths. It's important to use good thorough dental examinations to diagnose malocclusions at a young age and begin treatment to prevent associated problems. Depending on the age of the horse and the severity of the malocclusions, these corrections might need to be performed in stages and could take many visits over months to years to accomplish. In some cases, complete correction might not be possible due to age and severity of the problems present, and maintenance with the goal of comfort for the horse should be implemented.

During the exam of your horse's mouth, your veterinarian will be able to assess the severity of any malocclusions and make a plan with you for the correction of the overgrowths. Your vet might also choose to refer you to a more specialized dental practice for your horse's care. You should in no way fault your veterinarian if he or she chooses this route. Equine dentistry is a difficult, often messy, smelly, and bloody adventure, and in the case of periodontal disease, this goes double.

Those of us who have chosen to treat more advanced dental problems are well-equipped to handle the job and are able to schedule the time it takes to work on these cases. Many times a referral practice does initial treatments and the referring veterinarian does follow-up care.

Periodontal disease that is diagnosed early can often be treated by simply correcting the malocclusions that contributed to the problem in the first place. Regular maintenance of your horse's teeth will then help prevent a reoccurrence of periodontal disease. In more advanced cases, other treatment options might be implemented.

Treatment Step 2

Once the periodontal disease has been located and any overgrowths corrected, the feed and debris will be cleaned out of the area. Due to the painful nature of periodontal disease, the horse will require proper sedation. Often, local anesthesia or nerve blocks (similar to use of novocaine in people) are very helpful to keep the horse pain-free during treatment.

The veterinarian will use a combination of dental picks, forceps (to grasp and extract large feed particles), and irrigation to clean out the feed near the surface of the pocket. Mild or superficial periodontitis might readily respond to this type of cleaning.

There are high-pressure irrigation systems available that use a baking soda and disinfectant slurry for the treatment of equine periodontal disease. These machines, similar to those used in human and small animal dentistry, also contain high- and low-speed drills, air, and water delivery, a sonic scaler, and suction.

Once the affected area has been cleaned, the veterinarian will use a mirror and a periodontal probe to assess the extent of the disease. Malpositioned teeth might require careful reshaping to help prevent them from catching food and possibly allow them to reposition over time. The next step in treating these more extensive pockets involves protecting them from additional feed entering and beginning the disease process again before healing can start.

There are a variety of materials the veterinarian can use to protect the area. A sustained-release, biodegradable antibiotic might first be placed in the pocket to aid healing. Then a "bandage" of acrylic material can be placed to protect the antibiotic and the pocket. This material usually comes in two parts that, when mixed, harden to a rubbery consistency, allowing it to be form-fitted over the pocket.

The veterinarian will also consider prescribing a course of systemic antibiotics, depending upon the severity of the disease. She or he might also advise that you feed your horse exclusively pelleted feed for a number of weeks to allow healing to take place. Rough hay and forage can dislodge the impression material patch; complete or senior feeds (fed in the correct quantity) will sustain a horse through a period of time to allow healing to take place.

In the most advanced cases, a tooth or teeth might require extraction. Again, your local veterinarian might feel more comfortable referring these cases as the extractions can prove difficult.

Whether the pockets are cleaned and treated or a tooth is extracted, you should expect your horse to require frequent follow-up visits as the area heals.

Take-Home Message

With your horse's health and comfort the primary goal, it is important that periodontal disease and related dental problems are diagnosed and treated early for the best possible long-term results. The goal of treatment is a healthier, better functioning mouth, and ultimately, a happier, longer-lived horse.

By Drs. Colleen Porter and Thomas Johnson

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