How to tell a horses age by his teeth

illustration of horse molars

Cross sections
showing the effect of
wear of the teeth at
various stages.

Illustration - Cross section of horse tooth

Structure of the
lower incisor. As the
horse ages the
tooth is worn down
to reveal the patterns
shown in the 1st

The traditional way of determining the age of a horse is by looking at the horse's teeth.

There has been some dispute lately over how reliable this method is, but in most cases an experienced vet or horseman is generally pretty accurate in horses up to 12 years old.

The standard text on the ageing of a horse was published in 1912 by a Mr Galvayne.

Galvayne claimed that his method was infallible and that he could exactly age any horse or pony up to his mid teens and then give a very good assessment after that.

Theory behind ageing a horse by his teeth

The system of telling a horse's age by his teeth is based on the fact that the teeth continue to grow throughout the life of the horse.

As the crown of the tooth is worn away by chewing and grinding of food, more tooth erupts from the gum to replace it.

In horses the gradual eruption of more of the teeth changes their shape and alters the angle at which they meet.

The marks and depressions on the grinding surfaces also change as the horse gets older.

As it isn't very easy to see the molars at the back of the horse's mouth it is the incisors at the front of the mouth that are used to assess a horse or pony's age.

Incisor indicators

There are a few basic features of the horse's incisor teeth which , when taken together, can be used to give an estimations of the horse's age.

The features used to tell a horse's age are:

  • The change from milk teeth to permanent teeth
  • The presence or absence of the impression or infundibulum on the tables of the teeth (Shown in orange on the illustrations).
  • The presence of a hook or a groove on the upper corner teeth.
  • The marks or dental "stars" (Shown in orange on the top illustration) on the tables of the teeth.
  • The general shape and angle of the teeth.

Galvayne's Groove

According to Mr Galvayne, who gave his name to the it, Galvayne's groove and the hookon the upper corner tooth are the keys to accurate ageing.

Galvayne's groove is a well marked groove which appears on the side of the upper corner tooth at about 9 years.

The hook usually appears at 7 years old then is gradually worn away - another hook may appear at 11 years old.

Modern research has shown this to be unreliable - with hooks present in horses from 5 to 19 years old and Galvayne's groove appearing in horses from 5 to 29 years old.

Appearance of incisors in the horse's mouth

The horse's first teeth are milk teeth - these are replaced by permanent teeth as the horse reaches maturity. The incisors develop as follows:

  1. At birth a foal has no teeth, but the 2 central incisors cut at about 10 days old.
  2. The next pair of equine incisors, the lateral incisors, are cut at 4 - 6 weeks old.
  3. The 3rd pair appear at 6 - 9 months.
  4. At 2 and a half years old the horse's 2 central milk teeth are pushed out by the permanent central incisors.
  5. At 4 years old the permanent lateral incisors appear
  6. At the age of 5 the permanent corner incisors arrive and the horse is said to have a "full mouth".
How to tell a horses age by his teeth, based on the fact that the teeth continue to grow throught out the life of the horse - Looking at changes in the incisors and Galvayne's groove