CAPTIVATING CASES

Issue 20 - January 2016

Equine Lameness Consultation

Equine lameness is one of Animal Imaging's key areas of expertise. Equipped with its 3 Tesla Siemens MRI system, scintigraphy and digital radiography systems, Animal Imaging is able to take the guess work out of challenging lameness cases. Animal Imaging works closely with the referring veterinarian to provide a team approach to solving diagnostic problems without duplicating the referring veterinarian's previous diagnostic efforts.

Our goal is to assist in arriving at a definitive diagnosis. A treatment plan is recommended and can then be implemented by the referring veterinarian or if the referring veterinarian requests, implemented by Animal Imaging's doctors. Backed by years of equine experience, three board certified radiologists, and a state-of-the-art clinic and barn, Animal Imaging is a recognized national leader in the treatment of equine lameness.

CT Imaging of the Skull and Cervical Spine in Foals

Patient History:

An 8-month-old Arabian colt was presented to Animal Imaging for CT of the skull and cervical spine. He had a history of acute swelling and pain associated with the cranial cervical spine in the area of C1 and C2. He was also reluctant to move his head from side to side. The colt was suspected to have been caught under a fence. On cervical radiographs, an osseous fragment associated with the left wing of C1 and of the left cranial articular process of C2 was noted.

On presentation, the foal was bright and alert. Neurologic examination showed no conscious proprioceptive deficits. No weakness was noted on tail pull in either direction. No forelimb or hind limb ataxia was noted. The foal guarded its neck and preferred to keep his head held higher than normal, with little side to side movement. Crepitus could be palpated over the area of the first and second cervical vertebrae bilaterally.

Findings:

Multiple transverse CT slices of the caudal skull and cranial cervical spine to the caudal aspect of C3 were obtained with the patient under general anesthesia.

An axial CT image is shown on the left at the level of the cranial aspect of C2. On the right is a dorsal 3D reconstruction image. Both arrows show a mineral attenuating focus on the left side of the atlas, likely a displaced fragment from the caudal aspect of C1.

The sagittal CT image on the left and axial image on the right show mineral attenuating foci ventral to the dens of the second cervical vertebra.

Multiple small mineral attenuating foci were present adjacent to the atlantoaxial articulation, appearing more numerous on the left. Several mineral attenuating foci were noted at the ventral aspect of C1-2 and at the caudal dorsal aspect of C1 bilaterally. Larger fragments were noted on the left. A small mineral attenuating fragment was noted within the spinal canal to the left of the dens, but without evidence of associated spinal cord impingement. Multiple small, irregularly shaped defects were present within the left caudal articular surface of C1 and the left cranial articular surface of C2, with mild surrounding sclerosis.

Dorsal CT image showing articular defect and sclerosis of the subchondral bone on the left cranial aspect of C2

Left dorsolateral view. Cranial to the left. Arrow shows articular defect on the left cranial articular surface of C2.

No abnormalities of the surrounding soft tissue structures or caudal portion of the skull were identified.

Impressions and Recommendations:

Conclusion:

There was evidence of trauma associated with the atlantoaxial articulation, more severe on the left side where there was associated subchondral damage of the left atlantoaxial articulation. Multiple small surrounding osseous fragments were present bilaterally, more numerous and larger on the left. None of these fragments appeared to impinge on the spinal cord and most were located external to the spinal canal.

We recommended that the colt be placed on stall rest for the following two months, with NSAIDs used as needed. After this time, the referring surgeon will repeat a neurologic exam and radiographs of the cranial cervical spine. His response to rest will determine his prognosis for athletic use. The referring surgeon felt surgery was not indicated at this time. The articulation between C1 and C2 has been successfully lavaged under ultrasound guidance in the past.