Intervertebral Disc Disease

Intervertebral discs act as cushions between the vertebrae of the spine. Over time, degenerative changes and mechanical forces can cause these discs to bulge or rupture. When rupture occurs, the spinal cord is injured through compression and concussion. The severity of spinal cord damage and nerve cell loss depends on:

• the type of force applied
• the magnitude of that force
• the duration of spinal cord compression

Mild spinal cord injury may result in incoordination and an unsteady, “drunken” gait. More severe injury can lead to partial or complete paralysis of the limbs. The most severe cases involve loss of pain perception, which is associated with a guarded to poor prognosis, particularly when pain sensation has been absent for an extended period.

Chondrodystrophic breeds (such as Dachshunds, Pekingese, Beagles, and Lhasa Apsos) account for the majority of disc ruptures. Dachshunds alone represent approximately 45–70% of all cases. In these breeds, clinical signs typically appear between 3 and 6 years of age, although disc calcification may be evident on radiographs as early as 2 years.
Non-chondrodystrophic breeds (e.g., Labrador Retrievers, German Shepherd Dogs) more commonly present later, between 5 and 12 years of age.

Approximately 65% of disc ruptures occur in the thoracolumbar region (mid to lower back), while up to 18% involve the cervical region (neck).

Pain is often the earliest sign, but as neurologic injury progresses, deficits tend to follow a predictable sequence:

• Neck or back pain, with reluctance to move or walk
• Incoordination or a wobbly, crossing gait of the hind limbs
• Loss of voluntary movement in the hind limbs, often accompanied by loss of bladder control
• Loss of pain perception, indicating severe spinal cord injury and a poorer prognosis

Disc ruptures are categorized by spinal region to aid neurologic localization:

• Cervical vertebrae C1–C5
• Cervical C6 through thoracic T2
• Thoracic T3 through lumbar L3
• Lumbar L4 through sacral S3

This neurologic localization allows a board-certified veterinary surgeon to plan appropriate diagnostics and treatment. Intervertebral disc rupture is generally considered a true surgical emergency, with prognosis closely linked to neurologic function at the time of evaluation.

Initial evaluation may include general health screening and advanced imaging. Diagnostic options may include:

• Blood tests (CBC, serum biochemistry, urinalysis)
• Spinal and/or thoracic radiographs
• Myelography, where contrast dye is injected around the spinal cord to identify compression
• CT scan, either replacing or following myelography
• MRI, which provides superior soft-tissue detail
• Cerebrospinal fluid (CSF) analysis (spinal tap), when indicated

The choice of tests depends on the patient and the clinician’s judgment.

Conservative (non-surgical) management, consisting of strict confinement and pain control, is typically reserved for pets experiencing their first episode with mild neurologic deficits.

In most moderate to severe cases, surgical treatment is recommended. A variety of surgical approaches exist, depending on the location of the disc and the surgeon’s experience. In general, surgery involves decompression of the spinal cord by removing bone over the spinal canal (such as a hemilaminectomy) and extracting the herniated disc material.

Most pets are discharged 3–7 days after surgery. Follow-up visits are scheduled for incision evaluation and suture or staple removal. Pain is typically manageable with oral medications.

Postoperative care may include:

• Manual bladder expression 3–4 times daily, if needed
• Physical rehabilitation to improve strength and flexibility
• Strict activity restriction (“cage rest”) for at least 4 weeks
• Long-term lifestyle adjustments, such as weight control, use of body harnesses instead of neck collars, and limiting jumping

Potential complications include:

• Seizures shortly after myelography
• Surgical site infection
• Recurrence of disc disease (approximately 25% of patients)
• Persistent gait abnormalities or toe dragging

Prognosis depends heavily on neurologic status at presentation.

• Dogs that retain pain perception have an excellent prognosis, with up to 90% regaining limb function after surgery.
• With medical management alone, 60–80% may recover.
• Dogs with complete loss of pain perception have a poorer outlook: surgery restores function in 50–60%, while medical management alone results in recovery in less than 10%.

Recovery from intervertebral disc disease often takes weeks to months, with surgical patients typically improving faster than those managed conservatively.

Pets with paralysis frequently have difficulty urinating and may require bladder expression until neurologic function improves. These patients are at increased risk for urinary tract infections, urine scald, pressure sores, and self-trauma due to abnormal sensations (paresthesia). Proper nursing care, padding, and close monitoring are essential.