Horses can have up to 44 teeth.
When discussing horse teeth, we often refer to the dental quadrants to identify and number teeth ensuring consistency in record keeping. This is known as the Triadan system of numbering. A horse has four quadrants of teeth. The upper jaw (maxilla) is divided into left and right quadrants (100 and 200), while the lower jaw (mandible) is divided in the same manner (300 and 400). In one quadrant, a horse is capable of having a maximum of three incisors (front teeth), one canine, four premolars (cheek teeth), and three molars (cheek teeth). With four quadrants, this equals 44 teeth. Not all horses erupt canine or wolf teeth (first premolar), thus not every horse has the full set of 44 teeth.
A horse has its full set of adult teeth by approximately five years of age.
Young horses have deciduous (baby teeth) that are replaced by permanent teeth as they age. First, let’s discuss the eruption schedule of the adult incisors (front teeth). The central adult incisor erupts into the mouth at 2.5 years of age pushing out the deciduous tooth simultaneously. This is followed by the intermediate adult incisor erupting at 3.5 years and the corner incisor erupting at 4.5 years. Canine teeth erupt into the mouth at approximately 5 years of age. The adult premolars and molars (cheek teeth) come in between the ages of 1 and 3.8 years. This eruption timeline assists veterinarians in estimating the age of young horses when their birthdate is unknown.
Horse teeth do not GROW throughout their life but instead ERUPT.
Horses have hypsodont teeth meaning they have a very long crown. The part of the tooth you see when you look into the mouth is termed the “clinical crown” while the portion below the gingiva (gum-line) is called the “reserve crown.” The reserve crown is substantially longer than the clinical crown in young horses. The period of time when the teeth are actually growing is very short, while the period of eruption (reserve crown entering the mouth becoming the clinical crown) is quite prolonged and appears as if the tooth is “growing” into the mouth. The cheek teeth erupt into the mouth by approximately 2-3 mm every year.
The upper cheek teeth and incisors have additional anatomical structures called infundibulum.
One must understand that horse teeth are complex living structures with nerves, veins, arteries, and lymphatics within them, specifically within the “pulp.” The upper cheek teeth and incisors have an additional component to their anatomy called infundibula. Infundibula are infoldings of enamel within the tooth that do not possess any vital structures however are still capable of forming caries (cavities). Generally, infundibular caries are non-painful to the horse however should be monitored at each dental appointment as their progression can weaken the tooth predisposing it to fracture. Caries involving the pulp horn ARE concerning, painful to the horse, and must be addressed.