Your Cairn Terrier and Dental Health – Part 2

Other dental issues
Retained deciduous teeth
The deciduous teeth are the baby teeth. The deciduous teeth should fall out as the adult teeth start to develop and should be gone by the time the adult tooth erupts. Permanent teeth are usually fully erupted by 5-7 months of age.  Retained deciduous teeth cause several problems.
·      They are prone to fracture as they are thin and delicate.
·      They increase the risk of gingivitis as they contribute to oral crowding.
·      Retained deciduous teeth can impact on the palate causing trauma.
·      Retained deciduous teeth can put pressure on other teeth contributing to malocclusion.
·      Wear and tear on other teeth resulting in erosion of enamel.
If you see retained teeth, be sure to consult with your vet to see if removal is needed.

Normal Occlusion in Cairn Terriers
Cairn terriers should have a scissor bite where the teeth fit closely together – this allows them to get a very strong grip on prey and is a feature of their original purpose as working dogs that are to assist farmers and fishermen protecting crops and the catch from predation by vermin.

Scissor Bite: the inner side of the upper incisors fit very closely over the outer side of the lower incisors; the lower canines sit just slightly in front of the upper canines. A proper scissor bite is due to the upper jaw being just slightly longer than the lower jaw.

Malocclusion in Cairn Terriers
Level bite: the upper and lower incisor teeth meet precisely, upper on top of lower, rather than fitting neatly together  with the upper immediately in front of lower.  When the teeth meet surface to surface, they are subject to excessive wearing down. By the time dogs are older, the teeth may be worn down to small stubs.

Undershot Bite:  the lower jaw is longer than the upper jaw resulting in the lower incisors being in front of the upper incisors.

Overshot Bite: the upper jaw is significantly longer than the lower jaw so that the upper incisors are in front of the lower – but instead of being fitting closely together, the upper incisors are at a distance from the lower incisors.  An overshot bite is often caused by an abnormally weak lower jaw, and missing teeth in the lower jaw.

Open Mouth: dogs with open mouth malocclusion appear to have an open mouth even when it is closed.  In this situation, the premolars meet rather than overlapping as they should.  The tongue often protrudes abnormally when there is open mouth malocclusion.

Wry Mouth: when one side of the jaw is longer than the other side, it causes a misalignment between the two sides of the mouth. The mouth will not close properly.  This can cause significant eating difficulties.

In some cases, malocclusion is purely cosmetic, but it can be a serious issue resulting in oral trauma, pain, and difficulty eating. Malocclusion is usually caused by abnormal development of the upper or lower jaw but can also be caused by retained deciduous teeth pushing the permanent teeth out of alignment.  If you have concerns about your dog’s bite, be sure to check with your vet.  Keep in mind that when puppies are young, the maxilla and mandible grow rapidly and sometimes out of synch  with each other, so they transiently appear to have an incorrect bite (level, undershot or overshot).  While you do not want to allow concerns with the bite to go on too long before getting it assessed,  it is important not to rush into decisions about their bite as things can change quickly.

Tooth Damage
Tooth fractures – almost 50% of companion animals will have fractured teeth. Fractures can occur from trauma (falls, direct impact) but chewing on hard objects (bones, antlers, sticks etc) is a more common cause of tooth fracture.  Simple fractures that involve only the enamel do not require intervention but many fractures will involve the deeper structures of the tooth and require extraction or root canal therapy as they will be very painful and may result in the tooth becoming non-viable and infected.
Enamel erosion can be caused by:
o   Malocclusion
o   Retrained deciduous teeth
o   Chewing abrasive items such as tennis balls
o   Repetitive pulling on wire fences / crate doors etc