Tooth Age Estimation
The tooth age estimation is a way to approximate determination of the age of horses based on typical changes in the dentition .
General
The determination of the tooth age of horses played a major role in the horse trade in the past centuries , as there was usually no proof of pedigree for work animals.
In the case of gifts, however, the age of the horse was irrelevant: " You don't look a gift horse in the mouth ". There are similar proverbs in numerous languages (Spanish: “ A caballo regalado no se le miran los serves ” - ... you don't look at your teeth).
Even today, determining the age of the teeth is a basic component of veterinary training, because it is relatively easy and quick to carry out and an additional identity feature. For the structure of the bit in the horse see also tooth formula .
An estimate of the age of the teeth is also possible in other animals, including cattle and other ruminants , dogs and cats .
history
The method of tooth age estimation was taught by Pessina von Czechorod , who taught at the Vienna Military Veterinary School at the end of the 18th century . With the help of reliable criteria it was now possible to check the age of the previous owner.
With the development of this method of age estimation, resourceful forgers (" Rosstäuscher ") were soon found who tried to e.g. B. by branding customers (see below) to make horses look younger again. However, only less experienced people can be fooled with this, because experienced people always use several criteria.
criteria
The determination of the tooth age is based on several criteria:
- Eruption of the milk teeth
- Change of teeth or eruption of permanent teeth
- Wear and tear of customers: the cup-like enamel protuberances on the incisors are called customers ( infundibulum dentis , also brand or bean ) . They are 12 mm deep in the upper jaw in the erupting incisor and 6 mm deep in the lower jaw and wear about 2 mm / year. Then only a small dot remains, the customer track visible.
- Pulp cavity: With wear and tear, the pulp cavity filled with secondary dentine gradually becomes visible as a brownish line, so-called tooth star or nuclear track , towards the lip of the customer's track.
- Shape of the chewing surface of the incisors: As the incisors wear out, they are pushed further and further out of their tooth socket . Since the incisor changes its geometric shape towards the root, the shape of the occlusal surface also changes. It is initially transversely oval, then becomes rounded, later triangular and finally longitudinally oval.
- Einbiss and countersink: By not 100% coverage with the pushing out of the I3 (third incisor) of the upper jaw and lower jaw there is an uneven wear, the lower jaw as Einbiss referred to the notch on the upper jaw-I3 as countersink .
- Angle of the upper and lower teeth to each other: While the incisors are initially perpendicular to each other when viewed from the side ( pincer bite ), the angle becomes more and more acute as it is pushed out due to the different radius of curvature towards the root ( angular bite ).
In general, the estimate becomes more and more inaccurate with advancing age, but one can also miscalculate by a year or more with younger horses, since tooth abrasion depends on the feed and also varies individually.
Time table
| Age | criteria | image |
| 1 week | inner milk incisor (i1, forceps) erupts | |
| 1 month | middle deciduous incisor (i2) erupts |
|
| 5-9 months | Deciduous incisor (i3) erupts Primary dentition now completely |
|
| 2½ years | The pliers (I1) change, when they are around 3 years old they are in full friction second and third premolar (P2, P3) change |
|
| 3½ years | Change the central incisor (I2) and P4 M3 breaks through |
|
| 4½ years | Canine incisor (I3) changes Permanent hook tooth (C) breaks through (mostly only in the stallion) |
|
| 6 years | Client rubbed in I1 of the lower jaw |
|
| 7 years | Client rubbed off in I2 of the lower jaw | |
| 8 years | Client rubbed in I3 of the lower jaw | |
| 9 years | Client rubbed off in I1 of the upper jaw The incision in I3 of the upper jaw appears |
|
| ten years | Client rubbed off in I2 of the upper jaw The occlusal surface of I1 in the lower jaw becomes rounded. |
|
| 11 years | Customer rubbed off in I3 of the upper jaw Bite may appear |
|
| 16-20 years | Occlusal surfaces from I1-I3 in the lower jaw become triangular Upper and lower teeth are at an acute angle to each other |
|
| over 25 years | Occlusal surfaces from I1-I3 become longitudinally oval |
literature
- Franz-Viktor Salomon: teeth . In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine . Enke, Stuttgart 2004, ISBN 3-8304-1007-7 , pp. 251-264.
