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Additional News and
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Seeing is Believing
Do you know what’s in your horse’s mouth? By
Toots Banner DVM
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Good nutrition, a comfortable place to live and good
medical and dental care are top concerns for horse owners. Whether you’ve
owned horses for 30 years or just purchased your first, this article is
written to help you understand what takes place inside a horse’s mouth – and
how it can directly affect equine performance and comfort levels.
During the past 10 years, the field of equine dentistry has changed
significantly for the better. Just as human dentistry evolved from the days
of the Wild West (where teeth were extracted after merely a stiff drink for
the patient), equine
 dentistry
has recently had more advances in equipment, procedures and research then
ever before.
We better understand how different dental irregularities affect the ability
to chew, gain weight and create overall comfort during training sessions.
Ultimately, good dentistry enhances the performance in the equine athlete.
What’s Inside?
A normal adult horse with a full set of canines and wolf teeth has 44 pearly
whites, which means there are 32 teeth behind the front teeth or incisors.
A full examination includes looking for any damage from sharp teeth,
(including ulcers in the side of the mouth,) and irregularities such as
hooks, ramps and waves, which are changes in the chewing surface .
To examine all these aspects, your horse should have the same complete exam
as your family dentist practices on you, with a bright light and open mouth,
prior to beginning work. Anyone practicing equine dentistry without a
speculum and a good light source has a very real chance of missing problems
and irregularities.
Age and Schedules
The first age to check a horse’s teeth is within the first two weeks of
life, because the newborn will erupt 16 baby teeth in that period. It is
uncommon that any dental procedures would be done at that time, but if a
deformity (such as an under-bite or overbite “parrot mouth”) are discovered,
then a plan of action for correction can be established. It is important to
have the horse examined prior to bitting and training (usually at 18-24
months) to balance the mouth and remove any wolf teeth. These deciduous
“baby” teeth can get incredibly sharp – like icicles – which definitely have
an effect on the comfort with the bit and reining. If you add a tie-down or
any other training aid that causes the cheek to be pushed against these
sharp teeth, it’s no wonder that head tossing is a frequent problem.
A youngster will begin losing baby teeth at approximately 2 ½ years of age.
This natural progression starts with the central incisors, and is followed
by the second and third premolars (referred to as the #1’s, 6’s & 7’s in
dental terminology). This adds up to 12 deciduous teeth, in a 6-month
period, that are being pushed up out of the gum by the permanent teeth.
These deciduous teeth are then referred to as “caps,” which sit on top of
the permanent teeth until the tooth is completely released from the gum. The
cap often stays attached to a portion of the gum until the tongue or chewing
push it free. Some caps don’t release but are loose and packed with decayed
feed material and must be removed manually. As the #6’s come into wear, then
the rostral (or front edge) is rolled, which is called a bit seat. This is
done on both the upper and lower #6’s and is performed by your dental
practitioner to minimize any discomfort associated with bit pressure against
the soft fleshy oral tissue against the tooth. Beware that some
practitioners might remove up to half of the tooth while doing this
procedure; this is both unnecessary and reduces the amount of chewing
surface available.
Older Horses
Older horses frequently have the most severe dental problems. Dental
irregularities that exist in their mouths have probably been there since the
permanent teeth erupted. Unfortunately, this means they have probably ground
against each other for years, which exaggerates the irregularity.
Patience and balance are the keys to getting and keeping these horses
comfortable. All horses need thorough dental exams and maintenance yearly,
on average. Some require more frequent procedures, due to irregularities
such as a “parrot mouth,” or a horse that cannot be fully corrected in a
single visit. Dentistry should be considered a regular part of you horse’s
oral care just as the farrier is a regular part of your horse’s hoof care.
Technology is improving, and even better and safer equipment is being
developed each year. Through research and technology, the latest and best
treatments are available for your horse’s teeth.
Always Moving
A horse has what is called “hypsodont teeth” that wear and erupt
continuously during their lifetime. They start out roughly 3 inches long and
are down to ½ inch by the time they are 25-30 years old. The surface of the
tooth that wears or chews is the occlusal surface that is the same surface
that has many of these same previously described irregularities. A dental
practitioner should alter the teeth as little as necessary to reduce the
irregularity, provide balance to the mouth and comfort to the horse. It is
also important not to round or dome the tooth because it is difficult for
the horse to chew roughage with a cue ball. The chewing surface should be
leveled with rounded edges. There are certainly instances of those doing
equine dentistry taking off too much tooth (it is the operator, not the
tools, that cause this) as well as those who don’t take off enough to
balance, which is why good visualization and equipment is essential for
today’s equine athlete.
The concept of doing thorough equine dentistry is very important for your
horse. Thorough equine dentistry includes floating, balancing the occlusal
surface, and balancing the mouth.
Floating
“ Floating,” is rasping or blunting the sharp points that form on equine
teeth. The points are usually on the cheek and tongue sides and can cut,
abrade and pierce the surrounding soft tissue. The horse’s upper jaw is
wider than the lower jaw, and so it is offset and has a chewing angle of
10-15 degrees. Floating can be done with motorized equipment or hand floats.
Hand floats can do most of the work that motorized equipment can, with some
exceptions.
With motorized equipment, the procedure can be cleaner, less irritating,
more efficient and quicker, which results in overall comfort for your horse.
Just as we don’t want to sit in a dentist’s chair any longer than necessary,
your horse’s patience also runs out if the procedure goes too long.
Balancing the Occlusal
Surface
After floating, the occlusal, or chewing surface, must be balanced. As I
referred to earlier, the hooks, ramps and waves are the peaks and valleys
that have occurred over the months and years of tooth eruption. Few horses
have a level chewing surface, so most will need some degree of balancing. I
have often performed dentistry on a horse for an owner that has had the
teeth “floated” just a few months earlier. The horse may be still tilting
its head, dropping feed or continuing with bitting problems. The big
awakening comes when the horse is sedated, a speculum is placed on and
opened then a good light is shown into the mouth. To the observer’s horror,
the large rear hooks, mid-arcade wave or other irregularities that still
remain in the mouth.
Balancing the Mouth
There are three main areas of interest regarding balancing: the incisors,
the premolars/molars and the TMJ or temporomandibular joint. The TMJ is
where the lower jaw or mandible hinges on the head, allowing the horse to
graze and chew. For the mouth to balanced there must be even contact with
all the teeth, including the incisors. If the rear teeth are floated
properly and yet no attention is given to the incisors, this often leads to
the incisors sliding across without any molar contact. If the incisors are
reduced too much, this can create strain on the TMJ ligaments, causing
soreness. It is important to make sure that all three areas are working
together in unison.
Increasing Awareness
Over the past decade, tools have become available for equine dentistry, such
as motorized equipment with specially designed guards to protect the oral
cavity from abrasions and irritation.
Carbide blades, and now diamond chip blades, fit on hand floats and
motorized floats for smoother “floating.” Special units are used for
periosteal treatment on dental pockets and gingivitis, as well as air
abrasion for cleaning and equipment to do restorations. The field of equine
dentistry is advancing to the point that there is now an advanced study or
fellowship for equine dentistry for veterinarians through the American
Veterinary Dental College.
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Just How Old is Your Horse?
Find out for sure how old your horse is – just by examining his
teeth! |
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You are in the market for a new horse and you
receive a message that one has become available that fits your ideal
description. He big, quiet and just the right color, but no one is sure
how old he is. As you know, a horse’s age can be an important purchasing
factor.
Men and women began determining horses’ ages by changes in their teeth
more than 2,500 years ago. Several papers have been published on this
matter, but an Australian horseman named Sidney Galvayne wrote the first
modern work in the 1800’s. Galvayne discussed the use of the groove in
the third incisor that was later appropriately named “Galvayne’s
Groove.”
Unfortunately, studies later determined that his information was invalid
as the groove may be absent in more than 50 percent of horses between 10
and 30 years of age.
Think you’d like to evaluate your horse’s teeth? To do so, focus on the
lower incisors, which are the six teeth just behind the lower lip.
Changes that occur on the chewing surface and a knowledge of the
eruption tables are the main criteria used for aging. This article
focuses on the newborn to the 5 year old, and the next issue of ec
magazine will contain an additional article focusing on the aging teeth
of the adult and geriatric horse.
Using the Triadan System (fig 1.)
Typically, foals are born with the four central incisors (teeth
101-401). The next set of incisors (see numbers 102-402 in fig. 1)
arrive at 2 to 3 weeks of age, and the final set of incisors (103-403)
at 6 months. Fig 2. shows a yearling colt’s incisors.
 
The eruption of the deciduous incisors (also called “baby teeth or
caps”) begins when the horse is 2 ½ years old. At that time, the 101,
201, 301 and 401 “caps” begin to shed, due to absorption of the
deciduous tooth roots and by being pushed out by the four new permanent
teeth. This process will start with the 01 caps at 2 ½ years, and the
permanent teeth will be in wear 4-6 months afterward. A 3-year-old will
look like fig. 3 with the larger, more rectangular permanent 01s in
wear.
The 102-402 caps will erupt one year later at 3 ½
years (fig. 4) with the 02 caps gone and the permanent teeth exposed but
not in wear. Fig 5 shows a side view of a 4 year old with the 02s in
wear and the 03s are yet deciduous teeth. The 103-403 caps will erupt
one year later at 4 ½ years and be in wear by 5 years of age. Fig. 6
shows a 5-year-old with the 03s in wear and a slight incisor under bite
with the lower incisors protruding forward of the upper incisors.
  
As incisor changes occur in the horse’s mouth, please note that activity
also takes place with other teeth. Canine teeth (04s), sit just behind
the 03 incisors. Canine teeth are permanent teeth and are mostly found
in male horses. The canines will typically erupt at 4 ½ -5 years of age.
The wolf teeth (05s) are the first premolars, coming in as permanent
teeth and usually erupting at 6-9 months of age. Wolf teeth should be
removed prior to riding your horse because they can interfere with the
bit and become a hindrance to training.
The premolars are three sets of four teeth and are numbered 06, 07 and
08s. They typically erupt at 2 years 8 months (06s), 2 years 10 months
(07s) and 3 years 10 months (08s). Your horse will shed and replace 24
teeth from the age of 2 ½ years to 5 years. It is also important to
monitor the eruption of the teeth as sometimes the deciduous teeth do
not come out normally and can cause disfigurement. Incisor caps
occasionally must be removed manually.
Fig. 7 shows a 3-year-old with the lower incisors displaced caudally by
the caps (note the normal large upper 01s). Fig 8 shows a 4 ½-year-old
horse with all of the caps as well as all the permanent teeth – for a
total of 24 incisors!
  
As the incisors erupt and come into wear, changes
occur on the occlusal or “chewing” surface. As each incisor erupts into
wear, the infundibulum (an enamel infolding) is noted in the center of
the incisor and is simply called a “cup.” Fig 9 shows a 3-year-old with
cups in the incisors. The cups are present at eruption and will
disappear with the following schedule: 01s at 5-8 years, 02s at 7-11
years and the 03s at 9-15 years. This cup may be empty or filled with
feed particles and will continue to wear for years until reaching the
cement core. Once reaching and exposing the cement core with the
surrounding enamel ring it is then called the mark. The mark is used in
aging adult horse and will be discussed more in the next section. The
dental star (fig 9) is a yellowish-brown structure on the chewing
surface that becomes more apparent with wear.
 The dental star
will usually appear in the central incisors (01s) at around 4 ½ years,
the 02s around 5 ½ years and the 03s around 6 ½ -7 years. As the horse
ages, the dental star will have a white spot appear.
As you can see, estimating the age of horses by their teeth it is not an
exact science, and there are variations according to breed, environment
and pasture access.
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Remember: all deciduous, or baby teeth (also known as
caps), have completely shed or erupted by the time your horse is 5
years old. So now we must rely on the knowledge of how the tooth
changes in shape and the changes that occur on the chewing surface.
While the following article will help you to age your horse, it is
important to realize the accuracy of age determination decreases
significantly as your horse grows older.
When looking at the chewing, or occlusal surface, of the lower
incisors, it is important to realize the tooth will change in its
overall shape. This change is characteristic to the incisors but not
to the canines, premolars or molars. Note the comparison of the
horses’ mouths in figures 1 and 2.
In fig. 1, the teeth of a 6-year-old are elongated in a side-to-side
direction, while the teeth in fig. 2 of an 18-year-old are elongated
in a front-to-back direction. The incisor teeth erupt into wear in
this horizontal direction, and as the horse ages the incisors become
more oval around 10 years, triangular around 15 years and then more
rectangular (front to back) around 20 years.
Observing the shape of the 03’s (See Triadan Numbering System ) from
the side is also useful. In horses less than 10 years of age, the 03
teeth are usually more wide than tall. Around 10 years of age, the
tooth appears almost square then progressively gets taller as the
horse ages. That is why you get the “long in the tooth” appearance
in older horses as in fig. 3. The blue arrows note the tall versus
wide principal. The black arrow points to the Galvayne’s groove, and
as we discussed in part one, is not a consistent valuable tool for
aging older horses.
Now that we have noted the overall shape, let’s look at the center
of the tooth for different structures and shapes that help in age
determination. As previously discussed, the deciduous tooth is
replaced by a permanent tooth, which initially has a hollow center
looking like a “cup,” hence its name. The cup is the infundibulum of
the tooth, which is an enamel infolding in the chewing surface. In
fig. 4, the black arrows point to the dark cups on the 303 and 403.
This cup will begin to wear down and the hollow appearance will
disappear over time as the horse chews the grass, hay and grain in
his normal diet. The lower half of the infundibulum is filled with
cement and is called the “mark” or enamel ring. See the blue arrows
in fig. 4 and the black arrows in fig. 5.
The mark will initially be long and oval, then change to a more
rounded shape by 15 years of age. The marks will usually disappear
by the time your horse is nearing 20 years old.
The dental star will usually appear in the central incisors, or
01’s, around 4-5 years, the 02’s around 5-6 years and the 03’s
around 6-7 years. As the horse ages, the dental star will have a
white spot appear in the center of the star. Fig. 6 shows a
4-year-old with dental stars in the 01’s and fig. 9 shows dental
stars in all lower incisors in a 10 year old.
As you can see, the process of aging a horse by the teeth is not an
exact science. Other considerations must be made for horses that
have irregular incisors, such as those with a diagonal angle or a
parrot mouth (see fig. 8). The irregularities give uneven wear to
the opposite teeth, thus changing the normal architecture and wear
of the tooth. The irregularities may be caused by defects within the
incisors themselves, or may be a secondary problem resulting from
molar malocclusions such as caudal hooks, stepped teeth, missing
teeth or a wave mouth.
Problems in horses over the age of 20 may be more severe. The equine
tooth will typically last 25 years, and as the horse ages, the tooth
will wear shorter and shorter. With a short root, the tooth is not
as strong and is more vulnerable to uneven wear caused by irregular
teeth. Problems are even worse if older horses have had poor or
inadequate dentistry throughout their lifetime. The entire dental
arcades need to be balanced to give comfort to the horse and balance
to the mouth. Your horse should have dentistry that is designed to
balance the mouth and is more than “just a float.” If quality equine
dentistry is performed to balance the arcades, the long-term results
will be obvious. The teeth will wear more evenly, causing fewer
stresses on the jaw during chewing or riding, and a mouth that can
be more accurately aged.
So when you go look that gift horse in the mouth, you will have an
idea how old he should be. I’ve seen plenty of horses 20 years and
older that were supposed to be 8-year-olds. Remember: old horses
have rectangular teeth that are long from front to back. I hope this
helps further your knowledge of horses. and if you have any
questions, feel free to contact me.
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