Not including wolf teeth, mature female horses have anywhere from 36 to 40 teeth, while males generally have 40 teeth. The equine teeth are divided into two sections within the oral cavity—the incisors which are seen at the front of the mouth, and the cheek teeth which are made up of molars and premolars. The premolars and molars are tightly aligned against one another, creating a dental arcade. Canine teeth may be found in the large space located between the cheek teeth and the incisors. They are an evolutionary throwback and essentially serve no function nowadays. Wolf teeth are also an evolutionary remnant and are not found in all horses. When present, they are located in front of the premolars.
Horses are hypsondontic mammals, meaning that their teeth are tall and continue to erupt from the gums at a rate of roughly 2-3 cm per year throughout their lives. A circular motion is used in the chewing process. The result is the maintenance of the occlusal surfaces of the teeth. This natural circular motion is reduced when a horse eats predominantly grain or pelleted feeds rather than a grass and hay diet. The smaller feed particles cause the horse to chew in more of an up-and-down motion which ultimately alters the manner in which the teeth wear. The horse also reduces the overall number of chewing motions with grain, causing an alteration in tooth-wear patterns. Because the upper and lower teeth do not sit flat against each other, they can eventually wear unevenly with chewing, leading to sharp points on the edges of individual teeth and an unlevel occlusal surface in the grinding teeth in the back of the mouth. This condition is commonly referred to as “wave mouth”. If the teeth develop an abnormal wear pattern due to improper diet and/or insufficient dental maintenance, their outer enamel layer along the occlusal surface will wear prematurely and unevenly, leading to exposure of the softer underlying dentin. Ultimately improper wear can lead to tooth deformation and/or loss and gum disease. Once teeth are lost, the malocclusion of the tooth surfaces will further worsen and may lead to a variety of additional health issues.
Floating is a process whereby a qualified veterinarian or equine dentist removes any irregularities of the teeth using a “float” to file down the surfaces. If a horse lacks proper dental care, over time their ability to properly chew their food will be impaired. Poorly chewed food can lead to a failure of absorption of the calories and essential nutrients needed for a horse to maintain their weight and a balanced metabolism. As well, they may end up experiencing pain when using a bit which will lead to resistance and poor performance. A horse with poorly managed teeth may drop large amounts of feed while eating, or may even swallow too-large boluses of hay and grain which can result in a potentially life-threatening condition known as choke. In cases of choke, the esophagus is blocked by food material. While the horse is still able to breathe, they are unable to swallow food or water. This is a medical emergency which requires immediate intervention by a veterinarian.
Signs of dental disease include head-shaking, creating hay wads when eating, packing feed in their cheeks, swelling or tenderness in the face and/or jaw, foul breath or even a bad smell from the nose, resistance/pain when the bit is inserted into the mouth or when riding aids are being given, and even lameness. Additional abnormal physical signs of dental disease can include excessive salivation, weight loss, colic symptoms, choke, sinusitis, and undigested grain in the feces. The important takeaway with regard to equine dental health is to incorporate as much hay/grass as possible into the diet, increase the feeding frequency when possible, and add routine oral exams (including examination of the teeth, tongue and gums) by a qualified professional into the maintenance program.
The purpose of the following article is to provide an overview of the equine intestinal tract, including its anatomy, how it functions in a healthy state, the most commonly seen intestinal diseases, clinical signs of these illnesses, as well as therapeutic options to address the illnesses. Finally, preventative measures which can be used through proper diet and husbandry practices will conclude this article.
Over the course of time, man’s domestication of the horse has resulted in many alterations of its natural behaviors. In particular, the contents and frequency of the equine diet have been adjusted to make their care more convenient for humans.
After a horse has ingested a mouthful of food, the circular chewing motion is used to grind up the food into smaller particles which will then be mixed with saliva, forming a bolus. The bolus is then pushed to the back of the pharynx, where it is swallowed and passed into the esophagus.