Intervertebral Disc Disease (IVDD) in Dogs & Cats
Intervertebral disc disease is one of the most common causes of back pain, weakness, and paralysis in dogs. When a disc herniates and compresses the spinal cord, the result can range from mild pain to complete loss of mobility — sometimes within hours.
MRI is the gold standard for diagnosing IVDD because it directly visualizes the herniated disc material, spinal cord compression, and spinal cord damage that determine treatment and prognosis. At Sage Veterinary Imaging, our 3-Tesla MRI provides the highest-resolution spinal imaging available in veterinary medicine, giving surgeons the precise information they need to plan decompressive surgery.
SVI offers advanced MRI services at our centers in Round Rock, Texas; Spring, Texas; and Sandy, Utah.
IVDD at a Glance
What Is IVDD?
The intervertebral discs are cushion-like structures between each vertebra that absorb shock and allow spinal flexibility. Each disc has a tough outer ring (annulus fibrosus) and a gel-like center (nucleus pulposus). In IVDD, part or all of the disc herniates into the spinal canal, pressing on the spinal cord or the nerve roots that exit the spine.
This compression disrupts nerve signals traveling through the spinal cord, causing pain, weakness, loss of coordination, or — in severe cases — complete paralysis and loss of bladder control. The location of the herniation determines which body parts are affected: cervical (neck) disc disease causes forelimb and hindlimb dysfunction, while thoracolumbar (mid-back) disease — the most common location — causes hindlimb dysfunction.
| Type | Mechanism | Typical Patient | Onset |
|---|---|---|---|
| Hansen Type I | Acute extrusion — nucleus pulposus ruptures through the annulus into the spinal canal | Chondrodystrophic breeds (Dachshunds, French Bulldogs, Beagles, Corgis) ages 3–7 years | Sudden (hours to days), often severe |
| Hansen Type II | Chronic protrusion — annulus gradually bulges into the spinal canal | Large-breed dogs (German Shepherds, Labrador Retrievers) ages 5–12 years | Gradual (weeks to months), progressive |
| Hansen Type III | Acute non-compressive — high-velocity disc material strikes the cord without sustained compression | Any breed, typically during vigorous exercise | Peracute (seconds), often unilateral |
Signs & Symptoms of IVDD
The clinical signs of IVDD vary based on the location and severity of spinal cord compression. Veterinary neurologists grade thoracolumbar IVDD from Grade 1 (pain only) to Grade 5 (paralysis with loss of deep pain sensation), which directly correlates with treatment urgency and prognosis.
🚨 When IVDD Is an Emergency
If your dog suddenly cannot walk, is dragging their legs, or has lost bladder control, this may indicate severe spinal cord compression (Grade 4–5) that requires emergency MRI and surgery within 24–48 hours for the best chance of recovery. Loss of deep pain sensation (the inability to feel a toe pinch on the affected limbs) is the most critical prognostic indicator. Contact your veterinarian or nearest emergency hospital immediately.
How MRI Diagnoses IVDD
MRI is the gold standard for IVDD diagnosis because it simultaneously visualizes three critical things that determine treatment: the herniated disc material, the degree of spinal cord compression, and the condition of the spinal cord itself. No other imaging modality provides all three.
What Our 3T MRI Reveals
Disc herniation location and lateralization — MRI pinpoints exactly which disc has herniated and whether the material is central, left-sided, or right-sided within the spinal canal. This information determines the surgical approach (hemilaminectomy vs. ventral slot) and which side to approach from.
Spinal cord compression severity — MRI shows the degree to which the spinal cord is being compressed, which correlates with the severity of clinical signs and helps predict surgical outcomes.
Spinal cord signal changes — This is uniquely available on MRI. Increased signal intensity within the spinal cord on T2-weighted images indicates edema (swelling), hemorrhage, or myelomalacia (cord softening/death). These internal cord changes are the strongest predictor of surgical outcome and are invisible on X-rays, CT, and myelography.
Multiple disc assessment — MRI evaluates the entire spine in one study, identifying additional herniated or degenerated discs that may contribute to clinical signs or require prophylactic treatment (fenestration).
MRI vs. Other Imaging for IVDD
MRI
Shows disc, cord compression, and internal cord damage. Non-invasive. Evaluates full spine. Best surgical planning tool.
CT + Myelogram
Shows compression location but requires contrast injection into the spinal canal. Cannot assess cord damage. Invasive.
X-Ray
Shows narrowed disc spaces but cannot visualize the disc material, spinal cord, or compression. Misses many cases.
Which Breeds Are Most at Risk?
IVDD has a strong genetic component, particularly in chondrodystrophic (dwarf) breeds whose disc cartilage undergoes premature degeneration.
Highest-Risk Breeds
Dachshunds have the highest IVDD incidence of any breed — approximately 1 in 4 will be affected during their lifetime. French Bulldogs and English Bulldogs have rapidly rising IVDD rates, with cervical disease being particularly common. Beagles, Pembroke Welsh Corgis, Cocker Spaniels, Shih Tzus, and Pekingese are also significantly predisposed. Among large breeds, German Shepherds, Labrador Retrievers, and Doberman Pinschers develop Type II IVDD with age-related disc degeneration. Cats can develop IVDD but it is much less common.
What to Expect During an IVDD MRI Study
A spinal MRI for suspected IVDD typically takes 45–75 minutes. Your pet will be placed under general anesthesia to ensure complete stillness — even small movements can blur the images and obscure the disc herniation. Multiple MRI sequences (T1-weighted, T2-weighted, and sometimes contrast-enhanced) are acquired to fully characterize the disc disease and spinal cord status.
For dogs presenting as neurological emergencies (acute paralysis, loss of deep pain), our team prioritizes rapid scheduling. In many cases, the MRI study can be coordinated the same day or next day to allow timely surgical planning.
Results are interpreted by a board-certified veterinary radiologist and communicated to your veterinarian or surgeon the same day. For surgical candidates, the MRI report includes specific information about which disc(s) to target, the lateralization of the herniated material, and the condition of the spinal cord — everything the surgeon needs to plan the procedure.
Dr. Jaime Sage, DVM, MS, DACVR
Dr. Jaime Sage is the founder of Sage Veterinary Imaging and a board-certified veterinary radiologist (DACVR) with advanced expertise in diagnostic MRI for companion animals. Dr. Sage personally interprets complex cases and works closely with referring veterinarians to ensure every imaging study delivers clear, actionable diagnostic answers.
Her published research on MRI in veterinary medicine — co-authored with Dr. Patrick Gavin, a pioneer in the field — has contributed to advancing the standard of care for pets requiring advanced diagnostic imaging.
Why Choose Sage Veterinary Imaging for IVDD
Schedule a Spinal MRI Study
If your pet is showing signs of IVDD — back pain, weakness, wobbliness, or paralysis — MRI can identify the problem and guide the best treatment. For emergencies, contact us directly for expedited scheduling.
IVDD Imaging FAQ
Get Answers for Your Pet
If your dog is showing signs of IVDD — from mild back pain to acute paralysis — a spinal MRI can identify the problem, guide treatment, and give your veterinarian the clearest possible picture for the best outcome. Visit one of our locations to get started.