Shetland Sheepdogs, or Shelties, are fluffy, lovable dogs who look like smaller Collies. If you are a Sheltie owner or fan, you may have heard the news about a recent discovery of the genetic cause of the “lance tooth”, a tooth abnormality commonly found in Shelties, and how it relates to body size. Here is a breakdown of what Sheltie owners (as well as any curious dog lovers) need to know about this tooth condition and what this new study’s findings mean for Shelties!
First off, what is a lance tooth?
A lance canine tooth, also known as maxillary canine tooth mesioversion, is an upper fang tooth that develops so that the tooth tip points forward (as pictured above) instead of pointing downward as it should. It can occur on one or both sides of a Sheltie’s mouth. As a board-certified veterinary dentist, I have seen this in Shelties all over the country for decades. It is almost exclusively found in Shelties, so it was assumed to be genetic in this breed.
What happens if a lance tooth is left untreated?
If untreated, the mal-positioned tooth can:
- Crowd other teeth (causing periodontal disease),
- Irritate the lips (causing ulcerations),
- Hit lower teeth (causing pain and movement of those teeth),
- And in extreme cases, prevent the Sheltie from closing its mouth.
What are the treatment options?
Treatment options include removing the tooth via surgical extraction or orthodontic movement of lance teeth.
What did this new study discover about lance teeth?
Leigh Anne Clarke, PhD, is the lead researcher at Clemson University. She studies genetic or inherited diseases in dogs. In 2017, she began studying lance teeth in Shelties. In September of 2020, Dr. Clarke, along with her graduate student, Sydney Abrams, published a paper in Proceedings of the National Academy of Science that revealed their study’s findings.
The study looked at the genome (complete set of genes) of 78 dogs, collected from over 200 Shelties who did not share grandparents. They found an area on chromosome number 9 that contains two gene variants in Shelties with lance teeth. One of these genes controls the hormone responsible for normal growth. The weights and heights of the Shelties in the study were then compared, and researchers discovered that the Shelties with lance teeth were, on average, one inch shorter and six pounds lighter than the Shelties without the lance tooth abnormality. The researchers then looked at other dog breeds and wild dog species. They found this same gene variant on chromosome 9 only occurs in toy dog breeds. This gene mutation is also the same mutant growth protein found in humans with pituitary dwarfism.
What exactly does this discovery mean for Shelties?
Humans have been selecting specific dog traits through breeding for centuries. While small dog sizes have many positives for owners, this discovery means the selection for smaller Shelties probably also carries an increased chance of lance teeth. Finding this genetic marker for lance teeth means breeders can pinpoint which Sheltie has the genetic variant. This can help eliminate lance teeth which may prevent eliminating whole family lines of Shelties, as well as preventing the decrease in genetic diversity of this adorable herding breed.
If you are a Sheltie owner and have any questions or concerns about your pet’s mouth, contact your family veterinarian for an oral exam and dental radiographs. If your Sheltie does have a lance tooth, your family veterinarian may choose to refer you to Animal Emergency & Referral Center of Minnesota’s Dentistry & Oral Surgery Service.