Determining a horse’s age by its teeth

Equine Dentist Bill Lomas looks at whether it is possible to determine the age of a horse from the development of its teeth.

Within the first two weeks of birth the foal’s baby teeth (milk teeth) will appear and by the age of two a full set of milk teeth should be present, a total of twenty-four, twelve incisors and twelve cheek teeth.

Between the ages of two and five, twenty-four teeth will erupt, with up to sixteen teeth erupting simultaneously.

At five years of age, the horse should have a full set of permanent teeth, totalling 36 to 40. The four extra possible teeth are the canine teeth (canines), found usually only in male horses. These push through at between four and five years, and are not considered further in this context, as their wear is not age related.

Up to this age one can be fairly accurate in ageing the horse. From the age of six, when all incisor teeth are level and in occlusion with each other, we begin to tell the age by studying the shape and pattern of wear to the occlusion surface of the upper and lower incisors.

Next is the seven year hook which appears on the upper corner incisor because this tooth slightly overlaps the lower corner incisor. This is said to disappear at eight or nine years of age and to reappear as an 11-year hook. I find these hooks unreliable as I often see them still present in horses well into their teens.

Sidney Galvayne, an Australian-born horseman, travelled Europe in the 1880s making money by determining the age of sales horses by the appearance of their teeth. His system became the basis for ageing horses for the next 100 years.

Galvayne’s groove is found on the upper incisors at around ten years of age, starting from the gumline and working its way down the tooth. When half-way down the horse is said to be fifteen years old, and when it is all the way down the horse should be in its twenties.

Unfortunately, I find Galvayne’s groove in only around 50 per cent of horses, and find it is important to look at both sides as they often tell different ages.

A recent study, performed in 1995, casts serious doubt on the theory that the age of a horse can be determined accurately from the study of its teeth.

A large group of horses with documental evidence of their birth date was examined and the age was estimated both by professional practitioners and by computer analysts.

There was little difference between the accuracy of the computer and the professional observers, and neither method was very good.

At best, ageing is not an exact science. Sometimes the best we can do is establish whether the horse is young, middle-age or old.