What Is Intervertebral Disc Disease in Dogs?
Between each vertebra in the spine lies a cushioning structure called an intervertebral disc. These discs act as shock absorbers and allow the spine to flex and move. Each disc has a tough outer layer called the annulus fibrosus and a soft, gel-like inner core called the nucleus pulposus. Intervertebral disc disease (IVDD) occurs when disc material protrudes or ruptures into the spinal canal, compressing the spinal cord and causing pain, neurological dysfunction, and in severe cases, complete paralysis.
IVDD is one of the most common spinal conditions in dogs and one of the leading reasons dogs undergo emergency spinal surgery. Understanding it — and recognising it early — can make a profound difference to the outcome for an affected dog.
Two Types of IVDD
Veterinary professionals distinguish between two types of intervertebral disc disease, which differ in how they develop and which dogs they most commonly affect.
Hansen Type I — Acute Disc Extrusion
In Hansen Type I disease, the nucleus pulposus undergoes premature mineralisation — it hardens and loses its shock-absorbing properties. Under normal spinal movement, the hardened disc material bursts through the outer fibrous layer and is forcefully ejected into the spinal canal. This is an acute event that can cause sudden, severe spinal cord injury within minutes or hours. Type I disease is strongly associated with chondrodystrophic breeds — dogs with abnormal cartilage development — and typically affects younger to middle-aged individuals.
Hansen Type II — Chronic Disc Protrusion
Hansen Type II disease develops gradually over time. The outer fibrous layer of the disc bulges progressively into the spinal canal, slowly compressing the spinal cord over months or years. The onset is typically much less dramatic than Type I, with symptoms developing gradually rather than appearing overnight. This type is more common in large breed dogs and tends to affect older individuals.
Breeds Most Commonly Affected
Certain breeds face dramatically higher risk of IVDD than others.
- Dachshunds — by far the most strongly associated breed, with studies suggesting they are approximately 25 times more likely to develop IVDD than non-chondrodystrophic breeds. Their long spines and short legs create exceptional mechanical stress on the intervertebral discs
- Basset Hounds
- Beagles
- Cocker Spaniels
- Corgis
- French Bulldogs
- Shih Tzus
- Dobermanns — particularly affected by cervical (neck) IVDD
- Labrador Retrievers — more commonly Type II disease
Recognising the Symptoms
IVDD presents on a spectrum of severity, and veterinary neurologists use a grading system from I to V to classify how severely the spinal cord is affected.
- Grade I — spinal pain only, with no loss of neurological function. The dog may be reluctant to jump, flinch when touched over the spine, or cry out when moving
- Grade II — pain combined with ataxia (wobbly, uncoordinated gait) and weakness in the limbs, but the dog can still walk
- Grade III — significant weakness with the dog unable to walk normally but still capable of some purposeful limb movement — this is called non-ambulatory paraparesis
- Grade IV — complete paralysis of the hindlimbs, with loss of bladder and bowel control
- Grade V — complete paralysis with no deep pain perception — the most severe classification, indicating serious damage to the spinal cord
Key warning signs in everyday life include sudden reluctance to use stairs or jump onto furniture, hunching the back, carrying the head low, crying when lifted or stroked along the back, and any degree of wobbling or dragging of the rear legs.
IVDD Is an Emergency — Act Quickly
If your dog suddenly loses the ability to use their rear legs, this is a neurological emergency. Every hour of delay between the onset of paralysis and spinal decompression surgery worsens the prognosis. Dogs that progress to Grade V — where no deep pain sensation can be detected — face a significantly reduced chance of recovery, and this window closes faster than many owners realise. If you notice any sudden hindlimb weakness or paralysis, contact a veterinary surgery immediately and arrange transport that minimises spinal movement — carry the dog rather than allowing them to walk.
Diagnosis
Initial assessment involves a full neurological examination to identify the site and severity of spinal cord compression. Standard spinal X-rays can provide supporting evidence but are limited in their ability to directly visualise disc material in the spinal canal. The investigations of choice are:
- MRI — the gold standard investigation, providing detailed images of the spinal cord, individual discs, and the precise location and extent of compression. MRI guides surgical planning precisely
- CT scan — faster than MRI and very good at identifying mineralised disc material, making it particularly useful for Type I disease
- Myelography — an older technique involving injection of contrast dye into the spinal fluid, now largely superseded by MRI and CT but still used in some settings
Medical Management
For dogs at Grade I or early Grade II, conservative medical management is an appropriate initial treatment approach. Strict cage rest for four to six weeks is the single most important component — this means complete restriction of normal activity, with short, controlled lead walks only for toileting. Activity restriction allows the damaged disc to stabilise and the inflammation around the spinal cord to resolve. Additional medical management includes anti-inflammatory medication, pain relief, and physiotherapy or hydrotherapy as recovery progresses.
If the bladder is not functioning normally, the dog will require assisted bladder management — either manual expression of the bladder or catheterisation — until normal function returns. This is a skill that can be taught to dedicated owners with veterinary guidance.
Surgical Management
Surgery is recommended for dogs at Grade II with recurrent episodes or inadequate response to rest, and is strongly recommended for Grades III, IV, and V. The surgical procedure most commonly performed is a hemilaminectomy or laminectomy, in which the bone overlying the spinal canal is removed to access and decompress the affected area. Extruded or protruding disc material is then carefully removed from the spinal canal.
For Grade V dogs — those with no deep pain perception — surgery must ideally be performed within 24 to 48 hours of the loss of pain sensation for the best chance of recovery. Beyond this window, the chances of meaningful neurological recovery decline substantially, though surgery may still be considered and some dogs do recover even after longer intervals.
Nursing Care During Recovery
Dogs recovering from IVDD — whether managed medically or surgically — often require intensive nursing care at home:
- Deep, padded bedding changed regularly to prevent pressure sores in dogs with reduced mobility
- Regular turning of recumbent dogs — those unable to move themselves — every four to six hours to prevent lung complications and pressure injuries
- Assisted bladder expression or catheterisation if bladder control has not returned
- Physiotherapy including passive limb movements, massage, and eventually active exercises as the dog improves
- Hydrotherapy under veterinary supervision to rebuild muscle strength with reduced spinal loading
Prognosis
Dogs at Grades I to III have a good to excellent prognosis with appropriate treatment. Grade IV dogs treated surgically have a reasonable chance of recovering useful limb function. Grade V dogs who have lost deep pain perception have a guarded prognosis, but surgery should still be strongly considered — a meaningful proportion of these dogs do recover, particularly when surgery is performed promptly.
Prevention in High-Risk Breeds
Dachshund owners in particular can take practical steps to reduce the risk and severity of disc disease:
- Install ramps in place of stairs wherever possible, and provide ramp access to furniture the dog regularly uses
- Use a harness rather than a collar to avoid neck strain
- Maintain a lean body weight — even mild obesity dramatically increases spinal loading
- Discourage jumping from heights
- Be familiar with the early warning signs so that veterinary assessment can be sought promptly if any develop