Regular dental care is important to the development of healthy horses. A healthy mouth can help avoid the incidence of digestive problems such as colic, weight loss and poor feed utilization. A lot of people assume the stomach is the beginning of the digestive tract, but really it is the mouth/teeth. Without sound dentition the rest of the digestive tract is less efficient.
Modern day management of horses has had significant effects on equine dental health. Horses grazing pasture are able to use their teeth and jaws. The natural action of using the incisors to tear or cut the grass and the molars to grind it allows the jaws to be used with a full range of motion, thereby providing an advantage over stabled horses. Stabled horses have little natural wear of the incisors because of a lack of availability to tear or crop grass. As a result these teeth can grow too long and decrease the contact between the molars of the lower and upper jaws. Grinding becomes less efficient resulting in the development of hooks (sharp enamel points), resulting in less efficient digestion and feed utilization. It is of critical importance that horses undergo regular dental work in order to maintain a healthy mouth. In order to understand the importance of dental work we must first understand the basics of the equine mouth and the mechanisms of biting and chewing.
Horses evolved as grazing animals, and their teeth and mouth adapted to serve that function. Their teeth are divided into two major sections: the incisors, which are the teeth seen in the front of the horse’s mouth and the cheek teeth made up of the premolars and molars. The molars and premolars are lined up tightly against each other, creating the appearance of one chewing surface. This alignment of teeth is called the dental arcade. The incisors are separated from the cheek teeth by a large space. Canine teeth can be found in the space between the incisors and premolars. The incisor teeth are responsible for the grasping and tearing of food, while the cheek teeth are used for grinding of feed.
Horses’ teeth grow tall and form in the jaw until approximately seven years of age and continue to erupt from the gum after forming. A hard material known as cementum that forms part of the tooth and bone is deposited pushing the tooth out of the skull and through the gum line. The part of the tooth that can be seen in the horse’s mouth is called the clinical crown, while the portion in the jaw is called the body or reserve crown. Equine teeth have an interweaving fold of hard enamel and dentin. The enamel is important for grinding feedstuff. The chewing surfaces of the teeth must have enamel-to-enamel contact. If the teeth are offset by abnormal wear, tooth loss or abnormal growth, the enamel-to-enamel contact will be disrupted and the enamel will come in contact with the much softer dentin. This results in the dentin wearing away rapidly and deformation of the softer tooth.
Young horses have a total of 24 deciduous or milk teeth – 12 incisors and 12 premolars or grinders. Mature male horses have 40-42 permanent teeth and mares have 36-40 depending on the number of canine teeth present. Canine or bridle teeth erupt in the interdental space at 4-5 years of age in male horses. They will only appear 20-25% of the time in mares and are usually smaller than those found in males. The first premolar (wolf-tooth) may be absent or rudimentary. In most horses it is only present in the maxillary (upper) jaw.
In order for a horse to obtain food, it must first grasp the food. If they are grazing, the upper jaw (maxilla) slides slightly forward and the lower jaw (mandible) slides backward. As the head comes into position at the ground surface, the incisors (front teeth) should be aligned to cut or shear off the grass pasture. The lips, tongue, cheeks and hard palate work the food back into the mouth where the cheek teeth (premolars and molars) grind it up. The chewing cycle is a repetition of a cyclical movement. The lower jaw drops and slides sideways then closes with the upper jaw and then grinds across. These steps are called the opening, closing and power stroke phases of chewing. Some horses will consistently chew or process their food in one direction; others will process or chew their food in both directions. The important point to remember is that chewing (mastication or grinding) requires significant motion of the upper and lower jaw in relation to each other. This motion is reduced as the horse eats smaller feed particles. Horses eating grains and pelleted feeds may chew in almost an up-and-down fashion.
Dropping feed while chewing, nasal discharge, foul-smelling breath, weight loss and facial swellings might all be indications of dental disease. While the symptoms of dental diseases are often obvious, the actual cause of these symptoms requires a careful and detailed examination. For this reason, horses should have an oral exam once a year. It is important to do a complete oral exam and not just look at the teeth as other disease processes may be present in the horse’s mouth.
For horses with dental problems that can no longer chew their hard feed or hay, HYGAIN provides various feeds that can be wet and fed out in a mash, such as HYGAIN TRU CARE® an extruded senior feed and HYGAIN MICRBEET® and HYGAIN® FIBRESSENTIAL® two highly digestible fibre products.
Different feeding regimes may also influence dental characteristics. Early studies showed that differing types of food changed the degree of lateral movement of the cheek teeth during chewing. Horses fed concentrates had an increased vertical crushing component in their chewing cycle, with decreased lateral motion when compared to horses fed hay. Replacing oats with sugar beet pulp (HYGAIN MICRBEET®) increased the ‘expected’ normal dental attrition. Horses fed hay also spend longer chewing compared with horses fed a high concentrate/cereal diet.
Results from several studies support the theory that a diet high in roughage consumed by non-domesticated horses promotes dental health through a greater range of jaw motion and a slower chewing rate. However, the calorie requirements of high performance horses are more easily met by feeding more energy-dense concentrate feeds at the expense of fibrous foods. Under these circumstances, it may be necessary to perform more regular dental examinations in order to avoid dental irregularities.
Correct chewing and grinding of feed are essential to your horse’s health and well-being. Supplying your horse with pasture and long stem forage along with regular dental care will help your horse be healthier and have fewer dental problems. An annual oral exam should be an integral part of every horse’s health program.