Aging Horse Teeth

Question 1

What to look for when aging horses?

Answer 1

**Mostly looking at incisors, especially lower
-eruption of teeth
-growth
-continuous wear
-profile changes of teeth over time

Question 2

Eruption time criteria usage in aging horse

Answer 2

-can be accurate and used up to ~5yrs of age

Question 3

Wear pattern based criteria in horses

Answer 3

-less reliable
-depends on diet, feeding habits, environment, genetics, disease
-due to less wear, teeth of stabled horses tend to appear younger than they are, and horses grazing in sandy areas appear older

Question 4

First and most important step of aging horses

Answer 4

-determine if incisors are all deciduous, all permanent, or a combination of both

Question 5

How to determine whether deciduous vs. permanent

Answer 5

-Deciduous: fairly distinct neck, less cement, pale colour, fine grooves
-Permanent: gradual transition to gum line, more cement, darker colour, coarse grooves

Question 6

Infundibulum

Answer 6

-a funnel-shaped enamel infolding, lined by and filled at proximal end (bottom) with cement

Question 7

Cup

Answer 7

-cavity in center of infundibulum
- looks black due to accumulated debris

Question 8

In wear

Answer 8

-dentin starts to be seen
-begins when tooth reaches height of neighbours

Question 9

Level

Answer 9

-start to see a complete circle of dentin/enamel around cup

Question 10

Cup gone

Answer 10

-cavity within infundibulum has disappeared

Question 11

Enamel spot

Answer 11

-a mark
- at the bottom of the infundibulum
-made of a ring of enamel and enclosed cement core
-resistant structure, standing proud above surrounding

Question 12

Dental star

Answer 12

-section thru former pulp cavity
-now filled with repair/dark dentin
-surface smooth as surrounding, only darker colour
-changes shape over time from linear to round
-more rostral/labial to enamel spot

Question 13

Round

Answer 13

-tooth profile becomes roundish

Question 14

Triangular/rectangular

Answer 14

-tooth profile becomes triangular/rectangular

Question 15

Order of events for Incisors, 1, 2, 3 (deciduous)

Answer 15

-deciduous incisors erupt at ~6days, 6weeks, and 6 months
-incisors in wear at ~1yr, 1yr, and 2 yrs

Question 16

Order of events for incisors 1,2,3 (permanent)

Answer 16

-erupt at ~2.5, 3.5, 4.5 yrs
-in wear at ~3, 4, 5 yrs (approx. 6 months after eruption)

Question 17

Occlusal surface changes due to wear

Answer 17

-permanent incisors wear ~2mm/year
-cup gets smaller and finally disappears
-lower cup: ~6mm deep,
so cup gone ~3yrs after
in wear
-upper cup: ~12mm
deep, so cup gone
~6yrs after in wear
-dental star appears and changes from a line to a round spot

Question 18

When do cups disappear in horses?

Answer 18

-Lower incisor: cup gone at ~6,7,8 years
- Upper incisors: cup gone at ~9,10, 11 years

Question 19

When does enamel spot disappear in lower incisors?

Answer 19

~12-18years

Question 20

When do lower incisors become triangular?

Answer 20

~16-17 years old

Question 21

When do lower incisors become rectangular?

Answer 21

-more than 18yrs

Question 22

Galvayne’s Groove on upper incisors

Answer 22

-may appear on upper corner incisors (I3)
-not reliable, but can sometimes be useful
-a form of coarse groove

Question 23

When does Galvayne’s groove appear?

Answer 23

10 yrs

Question 24

Galvayne’s groove growth

Answer 24

-halfway down tooth at 15yrs
-reaches occlusal surface of tooth at 20 yrs
-only lower half at 25yrs
-gone at 30yrs (eventually tooth is worn down and groove will disappear)

Question 25

Labial profile of upper incisor 3

Answer 25

-view from labial surface
-looks wider than it is tall at ~5-9yrs old
-looks almost square at ~10yrs
-looks taller than it is wide (more than 10yrs old)

Question 26

When does upper incisor 3 appear?

Answer 26

4.5 yrs old

Question 27

Hook on I^3

Answer 27

-known as 7yr or 11 yr hook
-very unreliable, may or may not appear from 5-15yr

Question 28

Angle of upper and lower jaw

Answer 28

-can be used as a general guideline
-younger horses have more perpendicular jaws
-older horses have a sharper angle

Question 29

Purpose of age estimation of ox

Answer 29

-used in border crossing/slaughterhouse inspections
-less studied
- also based on eruption times and tooth wear (mostly on lower incisors and canine usually included as I4)

Question 30

Teeth of Ox

Answer 30

-only lower incisors
-dental pad
-Lower canine is considered a incisor

Question 31

Eruption times of Ox teeth

Answer 31

-eruption time variations can be more than 1 year
-First permanent incisor: 1.5-2years
-Second permanent incisor: 2-2.5 years
-third permanent incisor: 3-3.5years

Question 32

Wear of ox teeth

Answer 32

-start to wear from central to lateral