Q&A: Basic Equine Dental Anatomy

With Liana Wiegel, DVM, Pilchuck Veterinary Hospital 

Q: Why do horses develop sharp dental points? 
A: A horse’s mouth is different from ours, from jaw to tooth. When a horse is not chewing, his upper and lower incisors are resting on each other; the premolars and molars (cheek teeth) are not actually in contact. The maxilla (upper jaw) is set wider than the mandible (lower jaw) with an overlap of about two-thirds the width of a tooth. When a horse chews, his mandible moves to the left or right, and the cheek teeth on that side then slide into contact to grind the feed. Because of this motion, sharp points are created – just like if you were to file your nail in one direction at the same angle. The points form on the buccal (cheek) side of the maxillary teeth and the lingual (tongue) side of the mandibular teeth.  

Q: Why then do these sharp points need to be routinely floated? 
A: Horses’ teeth continuously erupt, a few millimeters a year, throughout their lifetime. When a horse reaches 20 to 30 years old, the tooth root can no longer produce a functional tooth crown, and the tooth becomes smooth and no longer functional for grinding. Constant eruption of new tooth, coupled with the grinding action when eating, continues to create sharp points. The rate at which a horse’s teeth erupt changes throughout her life, so a young horse will develop sharp points faster than a senior horse.  

Q: Why do some horses need their teeth floated more frequently than others, even if they are the same age? 
A: Just as some people have poor alignment of their teeth, so do horses. If a horse has an overbite (parrot mouth) or underbite (monkey mouth) confirmation, this will result in areas of the tooth that have no opposing tooth to grind against. A horse can even have proper alignment of her incisors, but have improper alignment of the cheek teeth. If there is no opposing tooth to grind against, the tooth will continuously erupt and create hooks, ramps and other abnormalities over time. Also, when a young horse loses his baby teeth, if the opposing tooth does not come in at the exact same time, the opposing tooth may overgrow and create waves or abnormal high points in the mouth. In addition, the teeth themselves can also be tilted or twisted within their space and create sharp points. Horses have live pulp chambers within the crown, like people, so this limits how much tooth your veterinarian can float to adjust the horse’s tooth back to the proper level.  

Q: Why is regular dental care important for my horse? 
A: Even if you do not suspect any problems with your horse’s teeth (can be indicated by weight loss, dropping feed, spitting out partially chewed hay, head tossing, etc.), it is best to have your horse’s teeth checked routinely so that your horse doesn’t develop dental abnormalities that require much more frequent dental floats to return the horse back to normal. Based on your horse’s oral exam, you and your veterinarian can discuss how frequently your horse needs routine dental care.  

Dr. Wiegel is an equine and small ruminant ambulatory practitioner at Pilchuck Veterinary Hospital. PVH offers both mobile and in-clinic equine dental care; to learn more, call 360.568.3111.