Ageing A Horse By Its Teeth

Last Updated on December 13, 2021

Have you ever purchased a horse with no “paper” or gotten a horse from a rescue?  Sometimes sellers are unsure of how old their horses are when their horses don’t have papers or are up for adoption or rescue. Aging a horse by teeth will help you determine its lifespan.

But, knowing how old a horse is can be extremely important for a horse owner to best cater to the horse’s needs and wellbeing.  So, how can a horse’s age be determined without a record or a paper trail?

Ask your equine dentist or vet! They can actually get a pretty good estimate of a horse’s age by the condition of a horse’s teeth.  They typically can’t give an exact birthday or even birth year, but they can give a good estimate that will help a new owner plan for the horse’s wellbeing. 

Common Indicators of Aging a Horse by Teeth

There are several things that a vet or equine dentist will look for in a horse’s set of teeth to determine the horse’s age.  To determine a horse’s age, your vet or dentist will look at the horse’s front twelve teeth, called their incisors. 

The University of Missouri describes the anatomy of the horse’s teeth in the following words: “The two central pairs both above and below are called centers, pincers, or nippers. The four teeth adjacent to these two pairs are called intermediates, and the outer four teeth are designated as corners. Canine teeth or “tusks” may appear midway between the incisors and molars at 4 or 5 years of age in the case of geldings or stallions, but seldom appear in mares. Adult horses have 24 molar teeth.”

In these teeth, your vet or dentist will look for a few characteristics to help determine the horse’s age.  They will look at the shape of the teeth, how many (permanent) teeth a horse has, whether or not “cups” are visible in the horse’s teeth and the angles of a horse’s teeth.

Aging a Horse by Teeth: Shape of the Teeth

The concept here is that the shape of a horse’s teeth will change throughout wear and tear over the years of his life.  When a horse is younger, his teeth are typically broad and flat, resembling something like a rectangle.  But, as he ages, they become more ovular and even triangular.

Permanent Teeth

Typically, by the time a horse is five years old, he will have all of his permanent teeth.  So, if he doesn’t have all of his permanent teeth, he must be somewhere between one and five.  Different teeth standardly appear between a horse’s first, second, third, fourth, and fifth birthdays, so it is relatively easy for vets and dentists to track a horse’s age when they are still this young.

Aging a Horse by Teeth: Cups in Teeth

When a horse has first developed his permanent teeth, there will be a “cup” on their surface, almost like a bowl shape.   Cups fade on certain teeth faster than others, throughout different periods of a horse’s life. The disappearance of this cup shape on certain teeth can give vets and dentists indication of a horse’s age.

Angles of Teeth

Without going into too much vet jargon, the angle of where a horse’s top row of teeth meets its bottom row of teeth can be used to help determine a horse’s age. As a horse gets older, his teeth start to point more outward than inward.  

Aging a Horse by Teeth: Cups in Teeth

Aging a Horse by Teeth: Age Accuracy

But, even with all of these methods, a horse’s teeth can not tell us exactly how old they are.  There are several age groups in particular that are hard to peg.

The first of these is young horses.  Horses under the age of five are constantly growing and so are their teeth.  A young horse’s teeth can change immensely within a 2-3 month time period. Because of this, vets and dentists have to be extra cautious when trying to age young horses.

Conversely, the teeth of horses over the age of 15 don’t really change too much.  At that point, the shape and angles of a horse’s teeth pretty much stay the same unless something drastic happens.

Four Groups Method

In order to combat this unavoidable ambiguity, the AAEP (American Association of Equine Practitioners) created a four-group ageing method.  Basically, they categorize horses into one of four age groups based on the analysis of their teeth.

Their age groups are 1-4 years, 5-9 years, 10-14 years, and 15-20 years.  They concede that ageing a horse over 20 years will pretty much be guess-work. 

In the 1-4 year age group, the AAEP says that they can give a fairly accurate age estimation, so long as they do it correctly. Here, they are looking for whether or not a horse has all of his permanent teeth or not, and how much these teeth have grown in.

In the 5-9 year age group, they are primarily looking at the cups on a horse’s permanent teeth, and to what extent they are still visible.  The shape can also start to be used to help determine a horse’s age during this timespan.

In the 10-14 year age group, tooth shape is the primary indicator of age.  Here, a horse’s teeth will still be square but might be starting to shift toward the ovular shape.  The angle of a horse’s teeth also begins to be relevant during this age group.

And, in the 15-20 year age group, shape and angle are the primary indicators.  The shape will be significantly more ovular than rectangular at this point, and the angle will be noticeably changing.


While ageing a horse by its teeth isn’t an exact science, it can help horse owners have a better idea of how old their horses are.  There are many different factors vets and dentists have to consider when they are ageing a horse by its teeth, and these factors change in importance and relevance over the lifespan of a horse.

I hope this article helped you better understand how vets and dentists age horses by their teeth! If so, please share this article and share with us your experiences ageing horses!


How are teeth used to determine age in horses?

The two most commonly used methods of determining age in horses are the tooth wear method and the dentition formula. The first is a visual method, which is based on how many teeth are worn down and how far they have been worn down. The second is a numerical method, which is based on the amount of wear on the various teeth and the width of each tooth.
The tooth wear method is based on the fact that teeth get worn down over time and the amount of wear is proportional to age. This method is generally not very reliable unless it is done in conjunction with a tooth development method. 
The dentition formula is a mathematical method of determining age in horses. It is derived from the number of permanent teeth present, the width of the crowns, the width of the periodontal ligament space (the space between the roots of the teeth) and the width of the periodontal ligament space in the molar region.

How do teeth affect a horse's lifespan?

According to an article in the Journal of Applied Animal Genetics, horses with well-formed teeth live longer than horses with decayed teeth. Tooth health is considered a major factor in longevity and health.
It is believed that good tooth health may contribute to a longer lifespan due to the positive effect on digestion and the immune system. Horses with decayed teeth are more prone to colic, diarrhea and other gastrointestinal issues.

What age do horses teeth change?

Horses have four different types of teeth. There are four incisors, one canine, two premolars, and three molars. The first set of teeth (the primary dentition) comes in at around six months old. By the time the horse is five years old, all the permanent teeth are in place.
The first and second molars will appear in pairs, one above the other, around six months after birth, but they will not erupt until the horse is three to four years old. The third molar can erupt at any time from three to ten years of age. 
As horses mature, their teeth will continue to grow and fill in.

Do horses teeth continue to grow?

Horses teeth continue to grow for their entire life. Their adult teeth continue to grow throughout their lives and will not stop growing even after they are fully mature. This is necessary because of the horses diet as the teeth are being constantly worn down when the horse is grazing or chewing hay and grains. 

Do older horses lose teeth?

Yes, horses do lose their teeth as they age. It's not unusual to see a horse with 3 or more missing teeth. As the horse ages and tooth loss occurs, the horse may develop periodontal disease (gum inflammation). The teeth are no longer held in place by the gums, and it is common for them to fall out. 
There are a number of things that can contribute to tooth loss. Some of these causes include: dental diseases, nutrition, genetics, and other medical conditions.