Jacobs Journal of Anatomy and Physiology

Clinically Silent Calvarial Defects in a Dog: Developmental Failure of Endochondral and Intramembranous Ossification

Published on: 2017-01-20


A 3-year-old Shih Tzu was examined for bilateral nasal discharge and sneezing. The dog had no apparent neurological deficits. Computed tomography (CT) of the nasal cavity and remaining head was performed. Imaging findings were consistent with a non-destructive rhinitis. Multiple well-defined, round to ovoid defects in the calvarial bones were an ancillary finding of the CT imaging. A thin layer of soft tissue attenuation was present spanning these defects. Severe hydrocephalus was also identified, with no evidence of parenchymal herniation through the calvarial defects. Findings are consistent with a congenital failure of both endochondral and intramembranous ossification involving cells from both neural crest and mesoderm origin.


Ossification defect, Calvarial, Endochondral, Intramembranous