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*Mainly West Highland White Terriers and Scottish Terriers, also other breeds
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Also known as: '''''Lion jaw'''''
*Arises at 4-8 months of age
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*Clinical signs:
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==Introduction==
**Discomfort during eating
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Craniomandibular osteopathy is a '''non-neoplastic, non-inflammatory proliferative disease of the bones of the head'''.
*Grossly:
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**Proliferative changes in mandible, occipital and temporal bones, including tympanic bullae
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Primary bones affected include the mandibular rami, occipital and parietal bones, tympanic bullae and the zygomatic portion of the temporal bone.
**Bilaterally symmetrical
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**Lesions may also occur in the limbs - less common
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'''Symmetrical''' involvement is common.
*Histologically:
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**Osteogenesis and resorption of periosteum, endosteum and trabeculae of the mandible
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The condition is believed to be hereditary, and it is an autosomal recessive trait in '''West Highland White Terriers''' and possibly in '''Scottish Terriers'''. It has been reported in other breeds such as the '''Labrador, Great Dane  and Doberman'''.
**Variable infiltration of lymphocytes, [[Neutrophils|neutrophils]] and plasma cells
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**Mosaic appearance
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The aetiology is unknown but there may be a link with infection.
*Intermittent progressive course
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*Lasts up to seceral months
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The condition usually occurs in growing puppies between the age of '''4 and 8 months'''.
*Usualluy self-limiting and non-fatal, however, discomfort may be so severe as to justify euthanasia
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==Clinical Signs==
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The owner may report that the dog has '''difficulty in prehension, mastication and swallowing of food''', and that it has pain around the mouth area.
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Temporal and masseter '''muscle atrophy''' are common.
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There may be '''palpable irregular thickenings''' of the mandibular rami or the temporomandibular joint.
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The dog will be unable to fully open its jaw, even under anaesthesia.
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There may be bilateral exophthalmos.
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'''Pyrexia''', up to 40°c, can occur.
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Less commonly, there may be swelling and lameness in one or several '''limbs'''.
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==Diagnosis==
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Clinical signs and radiography are used to diagnose the condition.
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'''Radiographic findings''' include: uneven, beadlike osseous proliferation of the mandible or tympanic bullae, extensive periosteal new bone formation affect the temporomandibular joint, fusion of the tympanic bullae and angular process of the mandible.
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'''CT''' may help evaluate the osseous involvement of the temporomandibular joint.
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'''Bone biopsy''' may reveal: osteogenesis and resorption of periosteum, endosteum and trabeculae of the mandible, variable infiltration of lymphocytes, [[Neutrophils|neutrophils]] and plasma cells, mosaic appearance
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'''Bone culture''' may help to rule out osteomyelitis if the diagnosis is uncertain.
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==Treatment==
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The condition follows an intermittent progressive course but is '''self-limiting''', and treatment is only '''palliative'''.
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Analgesics and anti-inflammatories form the mainstay of therapy, and may include NSAIDs such as carprofen.
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'''High-calorie, protein-rich food''' should be provided to help maintain adequate nutrition, and feeding tube placement may be considered in severe cases.
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The animal should be reexamined frequently to ensure adequate nutritional balance and pain control.
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Pain and discomfort may diminish at skeletal maturity at approximately '''12 months'''.
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Lesions may then '''regress completely'''.
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'''Prognosis''' depends on the involvement of the temporomandibular joint, as ankylosis and adhesions may '''permanently restrict jaw movement''' and eating.
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'''Rostral mandibulectomy''' may be a useful salvage procedure.
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'''Euthanasia''' may be the only option in severely affected animals.
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Affected animals should not be used for breeding.
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{{Learning
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|flashcards = [[Small Animal Orthopaedics Q&A 09]]
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}}
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==References==
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Niemiec, B. (2010) '''A colour handbook of small animal dental and maxillofacial diseases''' ''Manson Publishing''
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Lobprise, H. (2007) '''Blackwell's Five Minute Veterinary Consult: Small animal dentistry''' ''Wiley-Blackwell''
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[[Category:To Do - Helen]]
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[[Category:To Do - Review]]
    
[[Category:Bones - Hyperplastic Pathology]]
 
[[Category:Bones - Hyperplastic Pathology]]
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