Horses can experience a number of different dental issues over their lifetime, impacting their ability to chew and digest their feed.
Unaddressed dental issues can affect your horse’s health, condition, behaviour and performance. This is why it’s important to have your horse’s teeth checked by an experienced veterinarian or equine dentist on a regular basis.
Dental problems are the third most common medical problem seen in large animal practices in the U.S.
Unfortunately, postmortem studies show high levels of clinically significant, undiagnosed dental disorders in horses.  This means that many horses are not getting the dental care they need.
In this article, we will discuss some of the common dental issues facing horses as well as signs of teeth problems and their treatment.
Equine Dental Care
Equine dental publications exist from as early as 600 BC. By 330 BC, it was common practice to age horses by looking at their teeth.
Also around this period, the effects of periodontal disease were noted and treatments were recommended.
Since that time, equine dental knowledge has progressed slowly. It wasn’t until the 1600s that the technique to remove sharp overgrowths on the lateral edges of the upper cheek teeth became prevalent. 
To this day, published research on the prevalence of equine dental disease remains limited, but diagnostic techniques have been developed in recent years.
As a result, equine dental disease has steadily gained recognition as a widespread problem with a significant impact on the welfare of horses. 
Today, equine dentistry makes up a large part of veterinary practice, with up to 10% of a large animal veterinarian’s time involving dental work. 
The Horse’s Teeth
To understand some of the common dental issues that horses experience, it’s important to first understand more about their teeth, in general.
Unlike us, horses have hypsodont teeth that are high-crowned. Part of the hypsodont crown remains in the jaw after eruption and a horse’s teeth continue to erupt into old age.
This is likely an adaptation to allow the horse sufficient dental material to buffer against tooth wear during a long life that requires a large intake of plant material. 
Horses have between 36-42 teeth altogether, depending on their sex and whether or not they develop “wolf teeth”. In the front, they have six upper and lower incisor teeth which are deep-rooted. These teeth are used to grasp and tear grass and other plants.
Cheek teeth (molars and premolars) help to grind grasses to prepare them for moving into the digestive system. Horses have 12 premolar and 12 molar teeth divided into an upper and lower row on the left and right sides of the mouth.
These teeth erupt in a tightly packed unit, acting as a single grinding system.
Canine teeth erupt between 4-5 years of age and grow between the incisors and cheek teeth on both the upper and lower jaw.
Canines are mainly found in geldings and stallions and serve a purpose in fighting in wild horse herds. Mares occasionally grow canines but they are usually less developed.
Wolf teeth are small teeth that some horses develop between 6-18 months of age. They are found in front of the first upper cheek teeth and often fall out by the time the horse is 3 years old.
However, many times, wolf teeth are removed by veterinarians because they can interfere with the normal function of bits and also may cause pain or tissue damage. 
Signs of Dental Problems in Horses
Many horses do not show signs of dental problems. However, broken or irregular teeth may cause loss of appetite, weight loss, or a general loss of condition.
Other signs of equine dental problems may include:
- Difficulty or slowness eating
- Reluctance to drink cold water
- Holding head to one side while eating
- Excessive drooling
- Blood-tinged mucus in mouth
- Bad breath
- Reluctance to take a bit
- Headshaking during riding
- Resistance to training
Extensive dental decay and infection may lead to a sinus infection and occasional discharge from one nostril. Infection may also cause swelling of the face or jaw. 
Though any horse can experience dental problems, older horses are more prone to developing them.
Developmental Dental Problems
As young horses grow and develop, problems such as overjet (also known as parrot mouth) and underjet may arise.
Overjet, where the top teeth protrude further than normal over the bottom teeth, is the most common oral birth defect. It can result from exposure to poisons while the mare is pregnant or it may be an inherited trait.
Underjet is less common in horses. With this condition, the bottom teeth protrude further than the top teeth. However, both overjet and underjet can lead to problems chewing food. 
Extra teeth (a condition known as polyodontia) can also grow. This could be double rows of incisor teeth or extra cheek teeth. 
Other developmental abnormalities include upper cheek teeth that grow further forward than the lower cheek teeth. This can cause overgrowth of certain teeth and the development of periodontal disease in the abnormal spaces between displaced and normal teeth. 
Shedding Baby Teeth:
Shedding baby teeth can also irritate a young horse’s mouth and loose, displaced, or broken baby teeth can lead to chewing problems. 
Dental caps refer to the condition of baby teeth that remain attached to permanent teeth. They can be extremely sharp and may cut the cheek or tongue or interfere with eating. Dental caps need to be removed.
Abnormal Eruption of Permanent Teeth:
Abnormal eruption of permanent teeth is usually caused by trauma to the face or jaw. In cases such as these, the bud of the permanent tooth can be damaged by a fracture or possibly the repair process. Delayed eruption or impaction of cheek teeth is a common cause of bone inflammation and tooth decay. 
Permanent teeth can also erupt in an abnormal location due to overcrowding of teeth. 
Just like humans, horses can also develop dental caries or cavities. Caries refer to the decay or destruction of dental tissue by bacteria found in the mouth. 
There are two main types of caries in horses: peripheral and infundibular.
Peripheral caries do not usually cause serious problems, but if left untreated could lead to fractures and periodontal disease.
Feeding silage and high levels of corn-based processed feeds are associated with a higher risk of peripheral cavities. Increased access to quality pasture and feeding of grass hays appear to be protective against these cavities. 
Infundibular caries develop in the infundibula or the grinding surface of the maxillary cheek teeth. 
In a study of 706 UK horses, 45.5% were found to have infundibular caries. Older horses were more likely to be affected. 
Periodontal disease has been acknowledged in horses for centuries and was once described as the “scourge of the horse’s mouth.”
This disease causes inflammation of the structures that support a horse’s teeth including the gums, periodontal ligaments, and bone on which the tooth sits. 
Unlike periodontal disease in humans, equine periodontal disease is considered almost always to be a secondary disease process. Researchers believe it results from physical and mechanical disorders of tooth growth, eruption problems, or wear.
An exception is the typically minor form of the disease