Incorrect Bite (Malocclusion)
A dog's bite is determined by how the upper and lower incisor (front center teeth) teeth meet when the mouth is closed. The ideal occlusion is one in which the upper incisors just overlap and touch the lower incisors. This is called the scissors bite.
Overshot bite occurs when the upper jaw protrudes beyond the lower jaw, causing the upper teeth to overlap the lower teeth without touching. This condition is also called "prognathism". some breeds, such as the German Shepherd, will go through a normal stage as puppies in which the bite is overshot. The overshot bite may correct itself spontaneously in young puppies if the gap is no greater than the head of a wooden match. Improvement may continue through 10 months old, at which time the jaws stop growing.
Puppies with severe overshot bites may have problems, because as the adult teeth come in they can injure the soft parts of the mouth. This will require treatment.
Undershot bite, also called brachygnathism, is the reverse of the overshot bite; the lower jaw protrudes beyond the upper jaw. It is considered normal for brachycephalic breeds such as Bulldogs and Pugs.
Wry mouth is the worst of the malocclusion problems. In a dog with wry mouth, one side of the jaw grows faster than the other, twisting the mouth. This can be a severe handicap in grasping and chewing food.
Most malocclusions are hereditary, resulting from genetic factors that control the rate of growth of the upper and lower jaws. Some incorrect bites are caused by retained baby teeth, which push the erupting adult teeth out of line.
Puppies should be examined by the vet at 2 - 3 months of age to identify bite problems.
In most cases, treatment will not be necessary. If there is overcrowding or displacement of permanent teeth however, the problem should be corrected by tooth extractions or orthodontic procedures such as crown-height reductions or the use of spacers. Interventional orthodontics will disqualify your dog for conformation competition.
The overshot bite is definitely hereditary and may be passed on to members of the next generation. The undershot bite is hereditary in some breeds. Dogs with hereditary dental malocclusions should be eliminated from breeding programs. This does not apply to brachycephalic dogs, in which malocclusion is a breed characteristic.
Please contact your veterinarian if you have questions regarding this condition.
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