Dental Disorders of Horses
Horses, like most other domestic large animals, are herbivores (plant eaters). If a horse’s teeth do not function well, it will be unable to eat properly and its overall health may be at risk. Unlike human teeth, a horse’s teeth continue to erupt throughout its life. The continual eruption helps to compensate for the wear caused by frequent grazing. When the teeth are not worn down evenly, problems can arise. Horses require regular dental care and preventive treatment throughout their lives.
Dental conditions (such as broken or irregular teeth) are common causes of loss of appetite or weight or a general loss of condition. The classic signs of dental disease in horses include difficulty or slowness in feeding and a reluctance to drink cold water. While chewing, the horse may stop for a few moments and then start again. Sometimes, the horse will hold its head to one side as if it were in pain. The horse may "quid," that is, form its food into a ball in the mouth, then drop the food after it has been partially chewed. Occasionally, the semi-chewed mass of feed may become packed between the teeth and the cheek. To avoid using a painful tooth or a sore mouth, the horse may swallow its food before chewing it, leading to indigestion, colic, or choke. Uncrushed, unchewed grain may be noticed in the manure.
Other signs of dental disease in horses include excessive drooling and blood-tinged mucus in the mouth, accompanied by bad breath from tooth decay. There may be a lack of desire to eat hard grain accompanied by loss of body condition or poor coat condition. Extensive dental decay and accompanying infection around the teeth may lead to a sinus infection and occasional discharge from one nostril. Infection may cause swelling of the face or jaw. Sharp edges on the upper molars can cut the inside of the horse's cheek. A horse with a dental problem may be reluctant to take the bit, shake its head when being ridden, or resist training due to discomfort and cuts inside the mouth. The presence of wolf teeth may or may not be associated with reluctance to accept the bit.
If you or your veterinarian suspects a dental problem, a thorough physical examination, followed by a detailed and thorough examination of the mouth and teeth, is necessary. To do this effectively, the veterinarian may give the horse a sedative. Some horses may require general anesthesia.
Regular dental prophylaxis (preventive care) is important to maintain your horse’s health. Enamel edges should be filed down twice yearly while the permanent teeth are coming in (from about 2½ to 5 years of age) and as frequently as needed after that, depending on the diet of the horse. This procedure is sometimes referred to as floating. Horses that graze on free range or grass usually require yearly preventive care. Horses that are kept in a stall and fed hay and grain usually require at least twice yearly oral examinations and preventive care. The objective of dental prophylaxis is to remove any sharp edges of teeth ("points") and maintain the normal biting surface. Dental prophylaxis can often be done with simple restraint or the use of sedatives and pain medication.
Tooth extractions are sometimes necessary for decayed teeth (see Tooth Decay, below) or for wolf teeth in horses that are reluctant to take a bit. Some extractions can often be performed on sedated horses using local anesthesia ("blocks"), whereas others require general anesthesia. Root canals and other techniques that preserve the teeth are becoming more common.
In horses, the most common oral birth defect (congenital deformity) is parrot mouth, in which the upper jaw is relatively longer than the lower jaw. In horses, many cases of abnormal dental development result from exposure to poisons during pregnancy, although some are inherited. Extra teeth (polyodontia), such as double rows of incisor teeth or extra cheek teeth, are seen occasionally. Treatment is determined on a case-by-case basis and may require extraction or frequent floating of the extra teeth.
Shedding baby teeth can irritate the mouths of horses that are 2 to 5 years old. Loose, displaced, or broken baby teeth can lead to problems with chewing and biting.
Abnormal eruption of permanent teeth is usually caused by trauma to the face or jaw, in which the bud of the permanent tooth is damaged by a fracture or by the repair process. In horses, delayed eruption or impaction of cheek teeth (such as from overcrowding) is a common cause of bone inflammation and subsequent tooth decay. Permanent teeth can also erupt in an abnormal location due to overcrowding.
Most large animals have a lower jaw that is narrower than the upper jaw. In horses, this can eventually cause the development of enamel points on the cheek side of the upper teeth and on the tongue side of the lower teeth. "Shear mouth" is an extreme form of this condition in which the chewing surfaces of the teeth have a very steep angle. It may be seen in older horses. In such cases, treatment is often not completely effective. A special diet will probably be prescribed for affected horses. As described earlier, enamel points are best treated by regular filing (floating).
Wave mouth, step mouth, and hooks refer to a bite surface that is irregular. These conditions are caused by uneven wear of the teeth and are the result of local pain, misaligned teeth or jaws, or missing or damaged teeth. In time, abnormal spaces form between the teeth, which traps food and causes gum disease to develop. Such conditions are best prevented by regular, routine dental care. Once dental irregularities are severe, dental procedures cannot completely correct the problem. However, some improvement is usually possible, even in severe cases where dental care needs to be supplemented by a special diet.
Gum (periodontal) disease is infection and inflammation of the tissue surrounding the teeth. It is caused by the accumulation of many different bacteria at and below the gum line. This infection causes inflammation of the gums, the ligaments that anchor the teeth, and the surrounding bone. If periodontal disease goes untreated, teeth can be lost due to loss of their supporting tissues.
In all animals, some inflammation of the gums (periodontitis) typically occurs when teeth come in. However, if bite problems occur in large animals, severe gum disease is inevitable. In horses, this is a common result of gaps between teeth (which trap food), trauma to the mouth, fractured teeth, impacted teeth, and most importantly, irregular wear.
Infection may enter the soft center (pulp) of the teeth in various ways, including trauma, severe gum disease, and the spread of bacteria through the blood. Some horses may be prone to tooth cavities and infection because of incomplete development of tooth enamel. Depending on the site of the decayed tooth, there may be other signs of disease, such as inflammation in the mouth or sinuses. If a horse is not examined until a dental infection is advanced, it may be difficult to determine the initial cause of the problem. Abnormal eruption of teeth appears to be a significant cause of many dental infections in horses.
When tooth decay is advanced, extraction of the tooth is typically required. This procedure may require surgery with general anesthesia, although in some cases sedation and local anesthetics can be used. After tooth extraction, the surrounding teeth gradually move to close the gap where the missing tooth was located. However, this process is never complete, and the tooth opposite the gap will tend to be longer than normal because it has nothing to wear it down. These irregularities can be corrected by grinding and realigning the teeth every 6 to 12 months.
Because of the problems that a missing tooth can cause in horses, techniques to preserve the teeth are often considered. In some cases, it is possible to preserve an infected tooth by performing a root canal. This procedure involves removing the diseased tooth pulp and replacing it with synthetic material. The age of the horse and the extent of damage will guide your veterinarian’s recommendation as to the best course of treatment.
See professional content regarding dental disorders.