Many people are surprised to learn that dentistry is an important part of caring for horses properly. Similar to humans, horses have two sets of teeth over their lifetime. However, unlike humans, whose secondary or ‘adult’ teeth come in at the size that they will remain, horses’ teeth continue to grow and wear down, and can become problematic if their teeth do not wear evenly, as horses’ teeth continue to erupt from their jaw and grow over the course of their entire lives.
The horse’s baby teeth (deciduous teeth) are temporary, and the first deciduous incisors may erupt before the foal is born. The last baby teeth come in by the time the horse is about eight months old. These begin to be replaced by adult teeth by about the age of two and one-half. By the age of five, most horses have all of their permanent teeth. An adult male horse usually has 40 permanent teeth; while an adult mare may have between 36 and 40, as mares are less likely to have canine (bridle) teeth.
Horses are born with two types of teeth: the incisors, which are located in the front of the jaw and are the teeth that we see when we open a horse’s mouth; and the teeth along the cheeks — the premolars and molars.
During the course of the horse’s life, his incisors continue to grow in length; and the shape of the incisors changes, as well. Until the horse is about 11 years of age, the lower incisors are rounded and have an oval shape. As the horse ages, they become triangular and eventually rectangular in shape. At the center of each incisor is the “cup”. As the edge of the incisor wears, the cup will get smaller and eventually disappear from all the lower incisors by the age of eight, leaving an enamel spot in its place. The dental “Star” (the pulp cavity of the tooth) first appears at the age of eight in the first incisor. It starts first as a line, and then changes over to a large, round spot as the surface edge of the tooth becomes worn. The dental star is still visible even after the ‘cup’ and enamel spot have worn away.
There is a noticeable groove that appears after a horse’s 10th year, starting at the gum line of the upper third incisor. Named “Galvayne’s Groove”, it is a helpful means of determining the horse’s age. This groove will extend halfway down the tooth at 15 years, and all the way down the tooth by the age of 20. By approximately 25 years, Galvayne’s groove is halfway gone, and by 30 years, it has disappeared completely.
The “cheek teeth”, the premolars and molars, grow tightly against one another (no spaces for dental floss!) and appear to be as one solid chewing surface, referred to as the “dental arcade”. The incisors are used for grasping and tearing of food (in wild horses, mostly grasses) and the cheek teeth used for grinding the food. There is a large space between the two types of teeth (where the bit lies in a horse’s mouth); but within this space can be found canine teeth, and sometimes what is commonly referred to as “wolf” teeth.
Horses in the wild depend on grasses for their food, and wild horses, as well as pastured domestic horses, will graze continuously. And while grazing, horses will pick up dirt and grit in the process. This, plus the silicate in the grass, wears down the teeth. Stabled horses, however, may not get the benefit of this normal wear on their teeth. Their feedings are most often scheduled, not continuous, and include processed grains, concentrates, and hay. These softer foods require less chewing, and may also be responsible for allowing the horse’s teeth to become excessively long, or to wear unevenly.
The horse chews its food in a circular motion — with the lower jaw sliding along the upper teeth. This circular motion keeps the teeth worn down and maintains the contact between the surfaces of the teeth. This circular motion is reduced as the horse eats smaller feed particles, to the extent that horses eating grains and pelleted feeds may chew in almost an up-and-down (rather than circular) fashion. And when this circular motion is interrupted or when the teeth wear unevenly, this misalignment of teeth and jaws can cause a number of health and dental problems.
Most veterinarians are able to check your horse’s teeth and use a file, called a ‘float’ to file down sharp edges and enamel points that occur; however an equine dentist will have specialized in dentistry, and will be able to use their skills when more difficult situations arise. The dentist will use a full mouth ‘speculum’, a hinged metal device attached to a halter-type strap that goes around the horse’s head, in order to clearly see inside the horse’s mouth and examine his teeth with only minimal contact with his tongue. Horses are generally cooperative during the process. In some cases, the dentist will sedate the horse.
It is suggested that your horse’s teeth be checked and floated at least once a year; with older horses or those with dental problems, twice-yearly examinations are better.
What are the symptoms to watch for that indicate a possible problem with your horse’s teeth? A very common indicator can be found in your horse’s manure. If you notice whole oats or grain coming through, it means that the horse is not chewing his food properly. This is especially important to watch for in older horses, or those in poor condition. Grain in the manure is also an indication that the horse is not receiving the proper nutrition, and in addition to being a source of your horse losing weight, is costly in the long run.
Another common sign that your horse’s teeth need to be checked is “quidding.” Quidding describes a condition where the horse will stash a ball or bolus of hay, grass and even grain in the side of his mouth to counteract pain caused by his teeth. The pain could be from sharp, unevenly-worn teeth cutting into the horse’s cheek or tongue; or even from an infected tooth or gum. Storing a bolus of material in the affected area and pushing it down with his tongue can sometimes mask the pain. You will notice the little wads of roughage near where your horse is eating, when he drops them out of his mouth. This is a sure sign that a problem exists and is reason to call the dentist.
Another symptom similar to quidding is if you notice a strong odor coming from your horse’s mouth. The odor may not necessarily be foul, but may just smell a bit of fermented grass or hay, as was the case of one of our horses. The odor was not unpleasant, but it was different for that horse and, sure enough, after a visit from the dentist, it was found that he had some teeth that needed floating (filing) and he was masking the discomfort by storing grass in that side of his cheek to prevent his sharp teeth from cutting into it. He was not yet quidding, but that would surely have followed had the dentist not intervened.
Did you ever notice your horse tossing its head when pressure is applied to the bit, or suddenly becoming difficult or resistant to bridling? This habit can also be a sign that there are dental problems occurring. Normally, the bit sits in an area of the horse’s mouth between his incisors (front teeth) and his pre-molars, where there is a blank ‘space’ with no teeth. However, some horses do have vestigial first premolars, called Wolf Teeth, which are small peg-like teeth that sit in front of the first premolars (cheek teeth) right about where the bit would comfortably rest. They are much less common in the lower jaw (mandible) than the upper jaw, although very occasionally these evolutionary remnants are found in the mandible. In some cases, Wolf teeth can be shed, or can be knocked out by the bit if they are loose — but in most cases, they are extracted by the veterinarian or equine dentist.
With proper dental care, you may even extend the life expectancy of your horse — but at the very least, he will utilize his feed more efficiently and be a happier, more comfortable horse.