Myelography

• Diseases of the spine and the spinal cord in rabbits are most often the result of trauma (fractures, subluxations and luxations), although congenital defects and degenerative spinal diseases have also been reported.
• Myelography is used to determine if the lesion is causing spinal cord compression and must be performed after collecting a thorough history and performing physical examination, neurologic examination and plain radiographs.
• Myelography is performed by injecting a contrast medium into the subarachnoid space to radiographically outline the spinal cord.

Uses

• Determination of presence or absence of spinal cord compression in cases of trauma (fractures and luxations), congenital defects, degenerative spinal diseases, herniated disks, cysts, tumors and granulomas Spinal injury.
• Myelography is commonly used to investigate clinical signs such as paresis or paralysis of the limbs, fecal/urinary incontinence, perineal dermatitis, altered gait, reluctance to climb stairs or exercise, or grooming difficulties.
• A similar technique using the epidural space can be used to perform epidural anesthesia Anesthesia: regional/epidural.

Advantages

• Better than plain radiographs to assess compression of the spinal cord.
• Significantly cheaper than magnetic resonance imaging (MRI) Magnetic resonance imaging or computed tomography (CT) Computed tomography.

Disadvantages

• More challenging technique in rabbits when compared to larger mammals.

Anatomy

• Rabbits possess 7 cervical vertebrae, 12-13 thoracic vertebrae, 6-7 lumbar vertebrae, 4-6 sacral vertebrae and 16 caudal vertebrae. The most common arrangement is C7/Th12/L7/S4.
• In most rabbits the spinal cord terminates at the level of the second sacral vertebrae, and nerve roots extend caudally as the cauda equina. 
• The anatomy of the spinal cord in rabbits is similar to that found in other mammals.
• The subarachnoid space containing cerebrospinal fluid (CSF) is the site of contrast deposition for myelography .
• The epidural space containing fat and blood vessels is used for epidural anesthesia .

Alternative techniques

• Plain radiography Radiography: spine: it can detect fractures and luxations, but myelography is superior to detect spinal cord compression.
• Collection and evaluation of cerebrospinal fluid Cerebrospinal fluid: sampling: it can be useful to determine the etiology of inflammatory or infectious conditions.
• MRI Magnetic resonance imaging or CT Computed tomography.

Time required

Preparation

• Allow 30 min for anesthesia Anesthesia: overview, surgical preparation of the area of injection and preparation of equipment and consumables.

Procedure

• 10-20 min, including radiography.

Decision taking

Criteria for choosing test

• Clinical and/or radiographic indication of spinal cord compression.
• Unavailability of MRI or CT scan.

Risk assessment

• Risk of complications decreases when the lumbar area is chosen for injection and when the volume of contrast injected is kept low.