The age old practice of telling the age of a horse by looking at its teeth is one that continues even in this day and age. While it is not always an exact science due to better equine dental supplies in the modern age, the general concepts will hold true.
A horse grows two separate sets of teeth during its lifetime similar to a human. They grow baby teeth and permanent teeth. When a horse has grown its permanent set of teeth to completion it is considered to have a ‘full mouth’. It is easier to determine a horses age accurately when it is younger. However, with practice the general age of a horse can be determined at any stage of its life.
From the time a horse is born until it is roughly two weeks old the foal will will have two central upper and lower incisors. In latter weeks, roughly four to six, the laterals will appear. The corners appear after six to nine months.
After roughly a year of its life passes a horse will develop a full incisor set. This includes the middle, six upper, and lower teeth.
Usually the need for dentistry or equine dental supplies is fairly low at this time unless the horse has damaged their teeth in some fashion. A young horse that has trouble eating due to damaged teeth might not survive. Equine dentistry floats can be used if it is absolutely necessary. However, there is usually no reason to considering the fact that in time the horse will lose these teeth anyway.
After around two and a half years of life the central incisors, both the upper and lower teeth, will usually fall out. Afterward the permanent teeth will develop. This loss and replacement will continue with the laterals within the next year. In the same vein up to another year might pass while the corner teeth fall out and are replaced by their permanent versions.
As soon as the new teeth begin growing in they start to feel wear and tear. Confined horses may require more dental work than free-grazing ones. The natural grazing patterns of a horse will wear at the teeth and generally keep them smooth and somewhat even. In confinement this does not happen and the horse will require their teeth to be floated more often. Unlike human teeth, a horse’s teeth will continue growing throughout its life. If they are not being worn naturally equine dentistry floats will be needed to keep their teeth smooth and even.
During the time that these teeth are growing to completion, at around four to five years of age, some horses may develop small pointed canine style teeth behind their corner teeth. These are called tushes. This is a solid milestone for determining a horse’s general age as this readily marks them as being at least four or five years old.
By the time a horse is six years old they will normally have their permanent teeth. This is the time a horse owner should become intimately concerned with the horse’s teeth.
When horses have completely grown their permanent teeth this is not the end. There are a few more movements the horse’s mouth and teeth will make.
At age seven a hook will begin to show along the corner teeth in the upper jaw. A similar one will show up at age nine as well. At age eight the real difficulty in telling a horse’s age will begin. The primary methods for determining age will be made via the shape, surface wear and tear, and the markings on them.
Around this age a ‘dental star’ will normally show on the centrals. The laterals will begin to show triangular shapes on the tables of the laterals.
At the tenth year of a horse’s life a dark marking on the upper corner of the incisors will begin. This is known as Galvayne’s Groove. This groove grows downward as the horse ages. When this groove is about halfway down the corner teeth the horse will generally be about fifteen years old. A dental star should have appeared on all of the incisors by the time they are ten years of age as well..
When a horse is twenty years old the groove should reach down to the bottom of the teeth. At the top it will have begun to disappear. Normally the teeth will also slope outward by the point. By the time they reach the venerable age of twenty-five half of the groove should be missing from the top down. As the horse continues to age the gums will begin to recede causing the teeth to appear longer with each passing year.