HOW OLD IS YOUR HORSE?
Though not an exact science,
reading a horse's mouth can tell you his
approximate age.
While age can be determined by
teeth, horses at pasture will wear
down their teeth faster than horses
eating hay, grain and pellets.
Horsemen traditionally use teeth to
estimate a horse's age, but it's not
foolproof. A very young horse's age
is determined by which teeth are
present and which he's losing.
After that, age is determined by the
wear, making accurate age estimation
relatively easly only until the age
of 9 or 10.
Teeth are made of three materials
that vary in hardness and wear away at
different rates. The softest material
wears down and makes shallow spots,
while the hard enamel remains in more
protruding ridges. In very old horses,
Galvayne's groove, shape, slope and
grinding surfaces are taken into
account.
Baby Teeth
Baby teeth emerge soon
after birth. Sometimes the two front
teeth (top and bottom) are present at
birth. These temporary milk teeth are
smaller, whiter and smoother than
permanent teeth, and have a slight
indentation at the gum line.
The central
incisors in front and first set of
premolars in the back appear first. By
the end of the second week of life, the
next two sets of premolars appear. The
second set of incisors usually comes at
4 to 6 weeks of age. The third set (the
corners) appears between 6 and 9 months.
A yearling usually
has all 12 temporary incisors (six on
top, six on the bottom) and 12 permanent
premolars. He also has four permanent
molars farther back in the mouth, behind
the premolars.
By the time he's
2, all his milk teeth are fully erupted
and the incisors are all touching and
showing wear - especially the centrals,
which have been fully erupted the
longest.
Temporary incisors
are all present at age 2. Permanent
incisors are all present and level by
age 5. Between ages 2 and 5, some milk
teeth are shed and some permanent teeth
come in or grow up to the level of the
others. But at both ages 2 and 5, the
mouth is "level." The only visible
difference is that a 2-year-old has baby
teeth, while the 5-year-old has
permanent teeth.
Baby teeth are
shed in the order they come in, pushed
out by the erupting permanent teeth.
Sometimes a baby tooth doesn't come
clear out, trapping the permanent tooth
in the jawbone and causing an
enlargement on the lower jaw. These
"tooth bumps" are common in horses from
ages 2 to 4. Once the offending baby
tooth (called a cap) is removed or works
loose, the trapped molar can erupt and
the lump on the lower jaw disappears.
Permanent Teeth
The first
permanent molars appear at the back of
the mouth behind the baby teeth at 9 to
12 months of age. The second set
replaces all the baby teeth by 2½. Baby
teeth usually shed in the fall, starting
with central incisors.
The permanent
centrals are fully erupted by age 3. The
next incisors push out the milk teeth at
about 3½ years and are fully erupted by
age 4.
The corner
incisors erupt at age 4½ and are fully
in wear by age 5, at which point the
horse has a complete set of 24 permanent
cheek teeth.
All baby teeth are
replaced by age 4½ years. He'll have at
least 36 teeth: 12 incisors and 24 cheek
teeth. He may also have up to four wolf
teeth and four canines.
Canines emerge behind the incisors at
about 4 years of age, although not all
horses get them. They occur most
commonly in males.
Many horses
develop another set of premolars, called
wolf teeth, just in front of the cheek
teeth, at about 5 to 6 months of age.
They're often small, with short roots.
In some horses, they don't appear until
about 2 years of age. Some never erupt.
Wolf teeth are often removed before a
horse starts training because they can
cause the horse discomfort from a bit.
Estimating Age by Wear
After the horse is 5, the only way to
determine age is by wear, the shape and
slope of the incisors and the Galvayne's
groove that eventually appears in the
upper corner incisors. In a young horse
there are cups (indentations) in the
center of the tooth's grinding surface.
The cups are usually darker than the
rest of the surface, and a ring of
enamel surrounds the cup. As the tooth
wears, the cups gradually disappear. In
the lower incisors, the cups disappear
from the centrals at about age 6 and
from the corner incisors at 8.
Cups in upper
incisors disappear a bit later (from the
centrals by 9, the next ones by 10 and
the corners by age 11). The horse is
then smooth-mouthed. These changes are
gradual and not exactly the same for
each horse, since wear can vary with
diet. Horses biting off grass wear teeth
faster than horses eating hay, grain and
pellets.
Other Indicators
Up-and-down ridges
on the outside of the incisors start
forming on the centrals at 10 years,
then on the middle teeth and last on the
corners. The corner incisors have ridges
by the time the horse is 14 to 16 years
old.
Teeth also change
shape as the horse gets older. At first
the permanent teeth have oval surfaces.
By age 12, the surface of the central
incisors has become round. By age 17,
all of the incisors have round surfaces.
By age 18, the centrals are more
triangular than round, and by age 23,
all the incisors are triangular. After
that the grinding surfaces again become
oval.
It's easy to tell
the difference between the oval-surfaced
tooth of a 7-year-old and the oval tooth
of a 25-year-old. The young horse's
teeth are broad across the front and
narrower from front to back. The old
horse's teeth are long from front to
back and narrow from side to side. Young
teeth are also shorter and straighter
when viewed from the side. They meet at
almost a right angle. Older teeth are
longer and protrude forward.
The older the
horse, the more his incisors slant
forward, coming together in a point like
the beak of a bird. Teeth are quite long
by the late teens, but may become
shorter again in very old age as they
wear away.
Upper-corner
incisors develop hooks on the back
outside surface, which change with age.
A hook usually starts to appear at age 8
or 9 and is fairly pronounced by age 12.
If there's a hook on the corner tooth,
the horse is older than 7. By the teens,
this hook starts to wear off, due to
changing angle of the incisors and
different wear points. By 16, the hook
is usually gone.The gum line on the
inside of the mouth also changes with
age. In a young horse, it's fairly
straight across the tooth. In an older
horse, the gum sags down, making a more
irregular line (a scallop effect) and
exposing more of the middle shaft of the
tooth. Another clue to age is that the
inside of the jaw becomes thinner as the
horse gets old.
Normal Variations
The
wear and length of incisors can vary, which
is why it can take some skill to learn to
read teeth. Teeth of different individuals
may age at different rates, depending on
genetics. Some horses have old,
slanting-forward teeth at earlier age,
sometimes depending upon nutrition and
environment.
A horse fed hay
and grain all his life (rather than
biting off grass) will show less wear on
his front teeth and they will also be
longer. A horse pastured on sandy soil
may wear teeth faster due to the
abrasiveness of chewing sand with his
feed. (A 6-year-old eating short grass
in sandy soil may show an 8-year-old
mouth.)
A horse with an
overbite or underbite (parrot mouth, sow
mouth) where front teeth don't meet
properly won't have much wear, and the
unopposed tooth will grow too long. A
horse that chews wood or cribs will wear
down his incisors more rapidly than
normal. Dental work to smooth up an
uneven mouth may also change the
appearance of teeth, making it harder to
tell the age.
Source:
www.MyHorse.com
