Intervertebral Disk Disease in Dogs

Laurie Anne Walden, DVM

Intervertebral disk disease (IVDD), also referred to as slipped disk, ruptured disk, or herniated disk, is a relatively common cause of neck and back pain in dogs. Some dogs with IVDD also develop neurologic deficits like toes knuckled under, a wobbly gait, or the inability to walk. The prognosis depends on the severity of the injury and length of time before treatment. A sudden inability to walk is a medical emergency. Affected dogs might need urgent surgery.
 
Anatomy
The spine is a row of individual bones called vertebrae. The spinal cord runs along a bony canal through the vertebrae. Intervertebral disks sit between the vertebrae just below the spinal cord and provide cushioning and support for the spine.
 
Intervertebral disks are sort of like jelly doughnuts: they have a squishy interior (the nucleus pulposus) and a firmer, protective exterior (the annulus fibrosus). With IVDD, part of a disk herniates; it leaks or bulges beyond its normal location and presses on the spinal cord or on the surrounding nerves.
 
Types of IVDD
IVDD is classified according to the type of disk herniation. Type 1 IVDD has a genetic link: it’s most common in dog breeds with chondrodystrophy, which usually means dogs with short legs and a long back. In type 1 IVDD, the nucleus pulposus becomes mineralized (hardens) over time and eventually breaks through the annulus fibrosus into the spinal canal, bruising the spinal cord. This type of herniation can happen quickly, causing sudden symptoms. Affected dogs are often young adults.
 
Type 2 IVDD is caused by age-related breakdown of the annulus fibrosus. Weakening of the annulus fibrosus allows the disk to bulge upward against the spinal cord. Type 2 IVDD is more gradual than type 1 and is more common in older dogs. Intervertebral disk herniation can also be caused by trauma or strenuous exercise.
 
Dogs at Risk
Any dog can develop IVDD. These are the breeds at highest risk for type 1 IVDD:

• Dachshunds –the most common breed by far
• French bulldogs
• Beagles
• Shih tzus
• Lhasa apsos
• Pekingese

 
Type 2 IVDD is more common in larger dogs like these:

• German shepherds
• Labrador retrievers
• Dobermans

 
Symptoms
The symptoms of IVDD range from pain to paralysis, depending on the severity of herniation, the force with which the herniated disk material hits the spinal cord, and the duration of the injury. The mildest form of IVDD is neck or back pain with ability to walk and no neurologic deficits. Neck pain can cause limping, so the symptoms of a herniated disk in the neck can be mistaken for an orthopedic problem.
 
More severe spinal injuries progress through stages that worsen with time: limb weakness, neurologic deficits, inability to walk, inability to stand, inability to move the limbs, and finally inability to feel pain in the limbs. Dogs with spine injuries might lose their normal bladder and bowel function.
 
These are some of the symptoms of IVDD:

• Hunched back
• Standing still with nose pointed toward floor, not lifting the head
• Reluctance to move
• Yelping when moving neck or back
• Reluctance to shake head
• Lameness
• Limb weakness
• Wobbly, unsteady, or staggering gait
• Standing or walking with toes knuckled under
• Limp tail
• Inability to walk or stand
• Loss of bladder or bowel control

 
Diagnosis
A physical examination shows whether the patient has neurologic deficits and often reveals the approximate location of the injury in the spine. Advanced imaging techniques like computed tomography or magnetic resonance imaging are required to make a definite diagnosis and locate all of the affected disks. Radiographs (x-ray images) are less helpful for diagnosing IVDD but might be obtained to rule out other possible causes of the symptoms, like fractures, dislocations, bone infection, and cancer.
 
Treatment
Dogs with milder symptoms—pain, ability to walk, and no or mild neurologic deficits—are usually treated medically at first. A crucial part of medical management is restricting the dog’s activity to allow the annulus fibrosus to heal, similar to treating a sprain. Some dogs need strict crate confinement. Medical management also includes medication to relieve pain. Dogs that begin to feel better with pain medication can reinjure themselves if they resume normal activity too soon, so they usually need to continue strict activity restriction for weeks.
 
Dogs with neurologic deficits or pain that doesn’t improve with medical management often need surgery to remove herniated disk material and relieve pressure on the spinal cord. Time is of the essence; the longer the injury to the spinal cord is present, the worse the neurologic deficits and the worse the prognosis for recovery.
 
For dogs that can’t walk but can still feel sensation in their feet, surgery performed as soon as possible after symptoms begin typically gives the best chance of being able to walk again. Once pain sensation in the feet is lost, the odds of recovery are much lower even with surgery. Spine surgery is expensive and dogs need extensive physical rehabilitation afterward, so the decision to proceed with surgery depends partly on the dog owner’s financial situation and ability to provide long-term care.
 
Sources
Olby NJ, Moore SA, Brisson B, et al. ACVIM consensus statement on diagnosis and management of acute canine thoracolumbar intervertebral disc extrusion. J Vet Intern Med. 2022. doi:10.1111/jvim.16480
 
Spinella G, Bettella P, Riccio B, Okonji S. Overview of the current literature on the most common neurological diseases in dogs with a particular focus on rehabilitation. Vet Sci. 2022;9(8):429. doi:10.3390/vetsci9080429
 
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