Disease Description: A condition where the lower jaw is too long for the upper jaw.

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Disease Symptom: Undershot is a class III malocclusion that is also referred to as mandibular prognathism, maxillary brachygnathism, mandibular mesioclusion, or an underbite. This malocclusion is characterized by a shorter upper jaw and a longer lower jaw, resulting in lower teeth that are in front of the upper teeth. While this condition is normal for some breeds, such as Bulldogs, in many breeds it is unusual. An undershot jaw occurs when the lower jaw grows faster than normal and becomes longer than the upper jaw, and is usually evident around 8 weeks of age in puppies. This misalignment can cause soft tissue trauma, such as to the lips. When the incisors meet instead of fitting next to each other, it is called a level bite. When the malocclusion causes the lower incisors to be placed in front of the upper incisors, it is called a reverse scissors bite.

Disease Cause: The cause of overshot and undershot jaws in dogs relate to the increased or decreased rate of growth of the upper and lower jaws in relation to one another. This can occur due to a: Genetic disorder Trauma; Systemic infection ;Nutritional disorder; Endocrine disorder; Abnormal setting of puppy teeth; Early or late loss of puppy teeth.

Disease Diagnose: After a quick physical exam, your vet may have to sedate your dog in order to perform a thorough oral exam. This will assess your dog’s skull type and teeth location in relation to the teeth on the opposite jaw. Often, the placement of the upper and lower incisors in relation to one another can determine what type of malocclusion your dog has. Your vet will note any areas of trauma due to teeth striking those areas, and any cysts, tumors, abscesses, or remaining puppy teeth that may be present. A dental X-ray can also help to assess the health of the jaws and teeth. These diagnostic methods will lead to a diagnosis of an overshot or undershot jaw in your dog.

Treat Method: Treatment of a jaw misalignment will depend on the severity of the condition. If your dog has a misalignment, but can still bite and chew food without problems, no treatment may be needed. If the misalignment is caught early in a puppy’s life, it may only be temporary and may correct itself over time. However, there are times when intervention may be needed. If your puppy’s teeth are stopping the normal growth of his jaws, then surgery to remove those puppy teeth may be performed. This may allow the jaws to continue to grow, but will not make them grow. For older dogs who are experiencing pain and trauma due to misaligned jaws and teeth, oral surgery is generally performed to extract teeth that are causing trauma, to move teeth so that they fit, or to create space for a misaligned tooth to occupy. Other therapies include crown reductions or braces.

Breeder Advice: If your dog is genetically programmed to have an overshot or undershot jaw, intervention can help, but will not slow or stop the abnormal growth of either jaw. Prevent jaw misalignments in puppies by not breeding dogs who have overshot or undershot jaws.

Disease Description Source: Link