Abstract:
Craniomandibular osteopathy (CMO) is a proliferative, self-limiting, nonneoplastic disease of growing dogs characterised by excessive new bone
formation on the skull and mandible. The radiographic findings of CMO are
well described; however, limited reports of the computed tomographic (CT)
appearance are available. This paper aims to characterise the spectrum of
CT findings that can occur with CMO. The study is retrospective, descriptive,
multicenter, and includes 20 cases. Age at presentation ranged from 6 weeks
to 12 months, with no sex predisposition. Scottish terriers were overrepresented
(65%); other breeds included Cairn terrier, Jack Russell terrier, Staffordshire
bull terrier, labrador retriever, golden retriever, akita and Slovakian roughhaired pointer (one of each breed). Terrier breeds represented 80% (16/20) of
the patient cohort. Mandibular osteoproliferation was present in all patients
(marked in 80%, bilateral in 95%), affecting the rostral mandible in 25%, body
in 85%, and ramus in 80%. Tympanic bulla osteoproliferation was present in
60% (12/20) of patients (all marked, bilateral in 75%). Cranial osteoproliferation
(frontal, parietal, temporal, occipital bones or maxilla, or combinations of them)
was present in 90% (18/20) of patients (40% marked, 27% moderate, 33% mild).
Nasopharyngeal narrowing was seen in all 12 patients with tympanic bulla
osteoproliferation (67% marked, 27% moderate) and caused nearly complete
occlusion in two of them. External ear canal stenosis was seen in 55% (11/20)
of patients (63% marked, 37% moderate, all bilateral). Temporomandibular joint
(TMJ) impingement was suspected in 83% (10/12) of patients with marked
tympanic bulla osteoproliferation (75% bilateral). Osteolysis with a moth-eaten
pattern was seen in the mandible of 10/20 dogs, the calvarium of 5/20 dogs,
and the maxilla of 1/20 dogs (5%). Lymphadenomegaly (mandibular and medial
retropharyngeal) was found in 15/20 patients (70% mild, 30% moderate). The
most severe CT changes were seen in Scottish terriers. CT allows for detailed
characterisation of the bony changes associated with CMO, including the effects
occurring secondary to osteoproliferation surrounding the tympanic bullae
such as TMJ impingement, external ear canal stenosis, and nasopharyngeal
narrowing. Osteoproliferation affecting the cranium and the presence of
osteolysis were seen more frequently in this study than previously reported in
CMO.
