Radiographs of the cervical spine in horses can be challenging, but developing a system and becoming familiar with interpretation of these views can be very useful.
Here are some common guidelines to follow for cervical x-ray studies in horses…
When Are X-Rays of the Neck Indicated in Horses?
X-ray studies of the cervical spine are used to evaluate for a number of different conditions, such as cervical vertebral malformations, congenital malformations, trauma such as fractures, subluxations, osteoarthritis, or neoplasia.
Some of the symptoms that might lead a veterinarian to suspect an issue with a horse’s cervical spine include pain on palpation, stiffness or a reduced range of motion in the neck, neurological signs (ataxia, proprioceptive deficits), swellings or asymmetry of the neck, or even lameness or decreased competitive performance.
Advanced imaging, such as CT and nuclear scintigraphy, is becoming more common. A myelogram is sometimes indicated as well, for more information.
However, plain radiographs are usually the first line for diagnostic imaging. Plain radiographs can provide a lot of information, can be used to guide the next step of treatment or diagnostics, and may be performed with sedation, whereas other imaging modalities require general anesthesia.
An ultrasound study may also accompany neck radiographs, especially for evaluating the joints and soft tissues such as ligaments.
Performing Radiographs of the Cervical Spine in a Horse
Here are a few things that will help with smooth and efficient x-ray studies of the neck…
Make sure the generator is powerful enough for cervical radiographs, especially for the caudal cervical spine, which is a very thick region to shoot through due to surrounding musculature.
Know which views are needed (more on this below).
Carry all appropriate PPE, including cassette holders, lead aprons, gloves, etc.
Use appropriate technique for this region. This is typically a kVp of 70-90, while mAs can vary greatly between the cranial to caudal portions of the neck due to thickness.
The horse is typically sedated unless contraindicated and standing for the x-rays.
Markers should be used to clearly differentiate the different regions of the neck, so a vet knows which vertebrae they are looking at. Some vets find it’s easier to use tape on the cassette to mark the views.
Which Radiographic Views of the Equine Neck Should be Taken?
Lateral views are typically the first ones taken. The standard lateral-to-lateral view (which can be taken from either the right or the left side) can provide a good screening of the entire area.
The region is usually broken down into three overlapping shots: cranial, middle, and caudal. One disadvantage of a lateral-to-lateral view is that bilateral structures are superimposed.
Oblique views can help with the problem of superimposition and allow the vet to take a closer look at the side where a lesion is located. To provide a basis for comparison, both a right and a left oblique are taken for each region of the cervical spine (cranial, middle, and caudal).
Obliques are usually performed at an angle of 45-50 degrees from lateral—for example, dorsal-right-lateral to ventral-left-lateral oblique. A ventral to dorsal oblique technique has also been described. Either way, the direction of the shot should be clearly noted and compared to a reference of the same direction and angle, for accurate interpretation.
Additional views may be obtained if needed, especially if more focal shots are indicated to isolate an area in question.
VD views are typically not performed due to impracticality, because of the thickness of a horse’s neck, although it may be possible in smaller breeds or foals.
Interpreting Radiographs of the Equine Neck
Practice, good reference images for comparison, and familiarity with the anatomy of the region can all help with the interpretation of x-ray images.
A consultation with a radiologist can also be helpful.
Evaluate each radiograph in its entirety. Asymmetry, variations of normal anatomy, changes associated with degenerative joint disease, lytic lesions, stair-stepping between vertebrae, compression of the vertebral canal, or any other abnormalities should be noted.
Measurements of the vertebral canal can also be made and compared with standards, which can help with diagnosing more subtle compressive lesions.
By having a system for neck radiographs, knowing which views to take, and becoming familiar with the interpretation of these x-ray studies, a vet can determine the next step for a horse showing symptoms of a problem localized to the cervical spine.
Written by: Dr. Tammy Powell, DVM
