The teeth of dogs and cats usually fit together well enough to chew food without discomfort. “Malocclusion” is present when a tooth or some teeth are not able to fit comfortably when the mouth is closed. In veterinary patients, management of malocclusion (which can include shortening of the crowns or extraction of maloccluding teeth, or orthodontic treatment to move the maloccluding teeth to a more comfortable position) is designed to eliminate pain or serious malfunction, and is not performed for esthetic reasons.
Fig 1. Normal tooth occlusion in a dog.
It is not ethical to correct abnormally positioned teeth in show animals – the genetic abnormality that will be covered up by the orthodontic treatment may be passed on to future generations. Dogs or cats in which a malocclusion has been corrected cannot be shown and should not be bred – AVDC recommends neutering these patients.
The “bite” (the manner in which the teeth fit together when the mouth is closed) can usually be assessed in an awake cooperative patient. Although the bite is not “normal” in many dogs and cats, the critical determination is whether there is evidence of tissue damage (such as when a malpositioned tooth penetrates into the gum tissue or palate) or loss of ability to chew comfortably; in these cases, treatment is indicated.
When treatment is indicated, the specific type of treatment is dependent on the abnormality present.
The most common malocclusion in dogs is persistent (retained) deciduous (primary) teeth. This is especially common in toy dogs (e.g. Yorkshire Terriers, toy poodles, Chihuahuas), and the retained deciduous teeth can force the permanent teeth to erupt in an abnormal direction. In young animals in which a permanent tooth can be seen to be erupting while the equivalent deciduous tooth is still firmly in place, the retained deciduous teeth should be extracted.
Fig 2. Persistent deciduous canine teeth.
There are many other types or patterns of malocclusion, some seen typicall in particular breeds of dog or cat, and many of which are assumed to be of genetic origin. Each patient with a malocclusion requires a treatment plan that is best determined by a veterinary dental specialist. There are often several options for successful treatment; however, treatment of malocclusion can be complex, and complications can occur if the treatment is not appropriate or performed well, or if a follow-up examination is not performeda at appropriate intervals.