CT and radiographic skull morphometry in Cavalier King Charles Spaniel Dogs with and without COMS

Caudal occipital malformation syndrome (COMS) is a developmental disease of the skull affecting many Cavalier King Charles spaniel dogs. In COMS, a malformed skull results in compression of the cerebellum, brainstem, and spinal cord. Magnetic resonance imaging (MR) of the brain and spinal cord is often used to diagnose COMS, but the changes seen on MR do not always correspond well to the clinical signs in the patient. These signs can include debilitating neck pain and gait abnormalities. CT and radiographs (x-rays) allow better bone evaluation than MR. Since COMS is a disease of bone development, we propose that CT and radiographs will allow for improved assessment of the skull. We will then make several measurements of the skull for which normal values have been established in a previous study. We will compare these values to the results of a neurologic exam and brainstem auditory evoked response (BAER) test that will be performed the day before the imaging studies. BAER evaluates signaling pathways in the brainstem, which are likely to be affected in COMS. It is our hypothesis that CT and radiographs will be able to diagnose COMS. This project is currently on-going.

Image A is a radiograph of the back of a dog's skull. Image B is a transverse CT image of the same area. The occipital foramen is the opening in the back of the skull where the spinal cord exits the caudal brain. In Cavalier King Charles Spaniel dogs, the back of the skull is malformed, leading to crowding and compression of the caudal aspects of the brain (cerebellum and brainstem).
A B
Radiograph of back of a dog's skull Transverse CT of the back of a dog's skull
CT Sagittal Measures
CT Sagittal Measures