Agriscience 334
Equine Science
8892-A
Determining Ages of Horses
TEKS (c)(2)(B)
CLASS NOTES KEY
Aging a Horse
Physical changes within the body are constant and apparent in horses as they age. To a certain
extent, these changes affect the general outward appearance of the horse. It is possible to use general
appearance to estimate the age of the horse. However, a more accurate method for estimating the age of
a horse is provided by specific changes in a horse’s teeth. Basically, determining the age of a horse using
the teeth simply involves:

determining the number of permanent teeth and milk teeth present in horses less than 5 years
old;

determining the number of cups or indentions in the incisor teeth for horses between 6 and 12
years of age; and

noting the cross section and slant of the incisor teeth in horses greater than 12 years of age.
Value of Horses at Different Ages
The market value of a horse increases sharply with maturity and then decreases with age. This is due
to the comparatively brief productive life and even more limited peak usefulness of a horse. However,
for many purposes horses are quite useful up to 13 years of age and often much longer. January 1 is
considered to be the birth date of a foal, regardless of when it was born. For example, a foal born June 1,
2008 will be 10 years old on January 1, 2018. This practice developed mainly from racing and showing.
Every horseperson strives to have foals born close to the first day of the year to give the foal the
advantage of greater growth compared to horses born later in the year. This is especially important in the
younger age groups (racing or halter futurities for two-year-old horses).
Anatomy of Teeth
The tooth consists of an outer layer of ivory covered by very hard enamel. The innermost part of the
tooth consists of dentine and the pulp cavity containing the tooth’s blood and nerve supply. The enamel
of a tooth passes up over the surface of the tooth and extends inward forming a pit. A mark or cup is the
inside and bottom of the pit, which contains the cement of the tooth. Feed usually blackens the pit,
commonly called a “cup,” and gives it a characteristically dark appearance. As the rims of these cups
disappear through wear, two distinct rings of enamel remain. One ring is around the margin of the tooth
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and the other ring is around the cup. With wear, the cups become smaller; the cups also become more
oval, then rounded, then triangular in shape. Over time, the cups become shallower and, eventually, they
disappear. Further grinding of the tooth exposes the tip of the pulp canal or cavity in the center of the
tooth. The resulting tip is a “dental star.” The gradual wearing and disappearance of the cups according
to a rather definite pattern enables a horseperson to determine a horse’s age.
Number of Teeth
The immature horse has 24 temporary teeth. The number of permanent teeth varies by sex in older
horses. Mares may have 36 to 38 teeth. Stallions and geldings have 40 to 42 permanent teeth. The
difference in the number of teeth is due to the canine teeth, which are almost always found in males, but
only occasionally seen in females.
Types of Teeth
Horses have a set of temporary teeth that are replaced by a set of permanent teeth. The types of teeth
that are included in the sets of teeth include: incisors, molars, canine teeth, and wolf teeth. The
temporary, or “baby,” teeth are small, white, and have a well-defined neck region. They are wider from
side to side than they are long from front to rear, giving them an oval appearance. The permanent teeth
are yellow and are larger than temporary teeth. No well-defined neck region occurs in permanent teeth.
Permanent teeth have a generally round surface. Wolf teeth are vestigial premolars that occur in about
one-third of horses (both sexes). Wolf teeth are located in front of the molars on the upper jaw and may
sometimes be found on the lower jaw. Canine teeth are located in between the incisors and molars.
Canine teeth are almost always found in male horses, but are seldom seen in female horses.
Using Teeth to Age Horses
The following sequence of events can be used as a basis for determining a horse’s age: eruption
of temporary teeth, wear of temporary teeth, eruption of permanent teeth, and wear of permanent teeth.
Age indications of temporary teeth are as follows.
1. Appearance of temporary central incisors – approximately 8 days of age.
2. Appearance of temporary intermediate incisors – approximately 8 weeks of age.
3. Appearance of temporary corner incisors – approximately 8 months of age.
4. The molar teeth appear in pairs at about the same intervals as the incisors.
5. Cups disappear from temporary central incisors – approximately 1 year of age.
6. Cups disappear from temporary intermediate incisors – between 1 and 1.5 years of age.
7. Cups disappear from the corner incisors and all incisor teeth appear worn - 2 years of age.
Age indications of permanent teeth are as follows.
1.
Appearance of permanent central incisors – 2.5 years of age.
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2.
Appearance of permanent intermediate incisors – 3.5 years of age.
3.
Appearance of permanent corner incisors – 4.5 years of age.
4.
The premolars and molars appear at the same intervals as do the incisors.
5.
The canine teeth appear between 4 and 5 years of age, if they appear at all.
6.
A 5 year-old horse is said to have a “full mouth” because all permanent teeth are in
place.
7.
Cups disappear from the permanent lower center incisors – 6 years of age.
8.
Cups disappear from the permanent lower intermediate incisors – 7 years of age.
9.
Cups disappear from the permanent lower corner incisors – 8 years of age.
10.
Cups disappear from the permanent upper central incisors – 9 years of age.
11.
Cups disappear from the permanent upper intermediate incisors – 10 years of age.
12.
Cups disappear from the permanent upper corner incisors – 11 years of age.
13.
An 11 year-old horse is said to have a “smooth mouth” because all cups are gone.
14.
A hook (worn edge) may appear on the upper corner incisors at 7 and 11 years of age.
15.
Galvayne’s groove appears on the upper corn incisors around 10 to 11 years of age and
gets longer as a horse ages.
16.
As the horse gets older, the angle of incidence increases and the teeth wear down.
17.
Further, the gums recede and the teeth become more triangular with age.
Like humans, horses can have dental problems. Therefore, it is important to check a horse’s teeth
regularly to identify potential problems and maintain good health. Shedding of temporary molars can
cause problems for young horses. Some horses do not shed their temporary teeth before the permanent
teeth erupt, which causes a cap to form. A cap between the temporary and permanent teeth can pinch a
horse’s lips and tongue. Veterinarians can easily remove a cap from a horse’s tooth. Wolf teeth are the
remnants of embryonic dental material. Wolf teeth can cause a laceration in the horse’s mouth, so it is
general practice to have a veterinarian remove these teeth. Sharp edges on the molars (hooks) can cause
digestive problems in a horse or cause the horse to stop eating. These edges develop from continuous
growth of teeth and wear according to direction of the chewing motion of the horse. A veterinarian can
remove the sharp edges on the molars with a method called floating, whereby the teeth are “filed” with
special instruments.
Some horse people make an amateur buyer a “victim of trade tricks” by altering a horse’s teeth.
Because very young horses increase in value to a certain stage, people sometimes pull the milk
(temporary) teeth a few months early. This hastens the appearance of permanent teeth and makes the
animal appear older. “Bishoping” is the practice of artificially drilling, burning, or staining cups in the
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teeth of older horses. This is an attempt to make an older horse appear younger. An experienced
horseperson should be able to detect such deception. A person cannot reproduce the ring of enamel that
is always present around the natural cup. Furthermore, the slanting position and triangular shape of the
teeth of an older animal cannot be altered. A novice horseperson should always call an experienced
horseperson to make an examination if there is any suspicion that a horse’s teeth have been tampered
with in any way.
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