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Radiology Case
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Radiographic findings: There is severe smooth bone proliferation involving both tympanic bullae (a). On the right lateral oblique view, the right temporomandibular joint is wide (b). On the left oblique lateral views, there is caudal sub-luxation of the left temporomandibular joints (arrow heads). There is no evidence of bone lysis. No mandibular abnormalities are seen.
Radiographic impression: Severe craniomandibular osteopathy and secondary caudal temporomandibular sub-luxation.Comments: The cause of craniomandibular osteopathy
is unknown. Canine distemper virus infection of bone has been considered.
Craniomandibular osteopathy occurs primarily in young terriers (3 - 8
months). West Highland White, Scottish, Cairn, Boston, and other terriers
are most commonly seen. Other non-terrier breeds may also be affected.
The affected puppies generally present with a history of difficulty or
pain in opening the mouth, mandibular swelling, drooling, and prehension
abnormalities. Physical exam often will reveal varying signs including
firm, often painful mandibular and temporomandibular swelling, pyrexia,
restricted jaw movements, and in severely affected cases, masticatory
muscle atrophy. Painless swelling may also occur, especially in large
breed dogs.
The radiographic changes may include irregular (pallisading) bone proliferation
on the mandibular and tympanic bulla - petrous temporal bones. There may
be thickening of the cranium and osseous tentorium as well. The bone proliferation
may be present in several locations or may be isolated (like in this case).
The changes are generally seen bilaterally, but are not always symmetrical.
The bone proliferation generally slows and often begins to regress at
approximately one year of age; however, some bone lesions may be persistent.
The disease is self-limiting and there is no specific treatment. Anti-inflammatory
therapy may help with discomfort. Severe restriction of jaw movement carries
a guarded prognosis and the related lesions may be less likely to regress.
References
Ettinger, SJ, Feldman EC. Textbook of Veterinary Internal Medicine, Vol.
2, 4th ed., Saunders, 1995, pp.2088-89.
Dr. John Feleciano, DVM, DACVR
Dr. Renee Leveille, DVM, DACVR
