Computed tomography (CT) images are formed by a xray generator and detector rotating around the patient. The resulting information can be viewed as cross-sectional slices which can be set up in any direction the viewer wishes.
CT provides excellent bony detail and provides more soft tissue detail than standard xrays. Unlike xray images where the anatomy is superimposed, CT images avoid superimposition of anatomy; this is particularly important in a complex area such as the head, where superimposition makes interpretation of xrays challenging.
CT scans are very quick to run (generally less than a minute), however, the preparation and positioning of the patient takes time. Additionally, if the examination is performed under standing sedation (generally examination of the head and limbs from knees / hocks down), any movement will compromise image quality so repeat scans may be required.
Using our state-of-art CT scanner, we are able to scan more parts of the horse than we have ever achieved before in both standing and anaesthetised horses. Historically, standing CT imaging of the head was performed most commonly, but we are now routinely scanning more necks and limbs (from the knee / hock down) in standing horses.
Standing sedated CT examinations are generally a very safe and well tolerated procedure. CT of the head is extremely useful for the investigation of dental disease and sinus or nasal disease. Other indications for CT examination of the head include headshaking and assessment of trauma / fractures.
Standing CT of the limbs has proved valuable in diagnosis of varying causes of lameness, pre-surgical planning and more recently in screening to prevent the risk of catastrophic injury.
CT of the whole neck and top of the limbs (elbow, shoulder, stifle and pelvis) can be performed in anaesthetised horses in our dedicated CT scanner. The use of contrast agents (dyes that show up on the CT) can be used to delineate soft tissue structures both within joints and other fluid pockets and the vertebral canal. Anaesthetised studies of the neck with contrast solutions (myelograms) has proven invaluable for diagnoses in horses with neck pain and neurological conditions and directing targeted treatments.
CT of the thorax (chest) and abdomen (belly) can be performed in small ponies and foals, under anaesthesia.
Equine CT is still in its infancy and it continues to reveal many new conditions that we are trying to learn more about. In order to research the applications of CT in horses, we are always interested in hearing how individual horses have fared after they have returned home from having a CT scan. We may contact you and your vet in the future to find out how your horse has got on.
Another important way of increasing our knowledge is by correlating the results of CT with surgical and post mortem examinations. If your horse has previously had a CT scan and undergoes surgery on the same area, we would be grateful to hear of the findings. If for any reason your horse has to be euthanased, then we would welcome the opportunity to perform a post-mortem examination of the scanned area. In this way we can further increase our knowledge and expertise for the benefit of horses in the future.