Lance canine teeth and missing third incisors are developmental dental abnormalities prevalent in the Shetland sheepdog. Since these conditions are seen almost exclusively in the Shetland sheepdog, this suggests a heritable component. The goal of this study is to identify genetic markers associated with lance canines and missing third incisors to develop a genetic test for breeders to use as a tool to selectively breed away from these anomalies while optimizing genetic diversity in the breed.
Lance canines are caused by a rostral displacement of the canine tooth and are named for their lance or spear-like appearance. In some dogs the lance canine can cause improper shutting of the mouth, ulceration, and/or periodontal disease.
Figure 1: The photo on
the left (A) is a sheltie affected with lance canine, indicated by the green
arrow. The left upper canine tooth is displaced forward so that it is in front
of the lower canine tooth and pointed toward the snout. A sheltie with normal
dentition (B) is shown for comparison.
Treatment of lance canines typically involves extraction of
the affected tooth. Orthodontic repositioning procedures are also available but
can be costly.
Figure 2: Before (A)
and after (B) pictures of a sheltie that underwent orthodontic repositioning
procedure to correct a lance canine.
Missing Third Incisor
Dogs with missing third incisors are lacking the upper deciduous
incisor, permanent incisor, or both. Often when the deciduous incisor is
present but not the permanent, there is delayed eruption of the deciduous upper
third incisor and the deciduous incisor is retained throughout the dog’s adult
Figure 3: A sheltie
with a missing deciduous upper third incisor (A), indicated by the green arrow,
is shown on the left. On the right (B) is a dog that is missing its permanent
third incisor but has a retained deciduous incisor, indicated by the green
We are currently collecting DNA from Shetland sheepdogs in
three phenotypic categories: complete dentition, affected with lance canine/s,
and affected with missing third incisor/s. For more information, please contact
Sydney Abrams at firstname.lastname@example.org