Intervertebral disc disease in dogs is a condition in which the discs between the vertebrae of the spine collapse and lose their function. IVDD is also referred to as a slipped disc or herniated disc. The intervertebral discs are made up of a tough material called annulus fibrosus that surrounds a soft, jelly-like center called nucleus pulposus. The discs act as cushions between each vertebra to absorb shock and provide stability to the spine. Dogs can spontaneously develop intervertebral disc disease but it can also occur due to injury or trauma.
What are the normal functions of an intervertebral disc?
Intervertebral discs sit between the vertebral bodies (spinal bones) and have several important functions:
What is intervertebral disc disease in dogs?
Intervertebral disc disease (IVDD) is characterized by herniation or protrusion of intervertebral disc material into the spinal canal, resulting in pain, weakness, or paralysis. Intervertebral disc damage is caused by a variety of factors, including genetics and traumatic injuries. Traditionally, disc herniation can take one of two forms: extrusions (Hansen type I) or protrusions (Hansen type II). Both types differ from one another in the onset of symptoms and in the breeds/species that are affected.
Disc extrusions (Hansen type I)
With this form, intervertebral disc material herniates into the spinal canal. Extruded disk material might be substantial and consume more than half of the spinal canal space. Type I IVDD typical results progress in a very short period of time, minutes to hours.
Breeds with shortened limbs (chondrodysplastic breeds), especially the dachshund, exhibit a higher rate of Type I IVDD and herniations. In chondrodysplastic dogs, the onset of degenerative disc disease usually happens before two years of age, but the herniation typically occurs by 3-6 years of age. Genetic predisposition is the most likely cause of IVDD in chondrodysplastic dogs such as dachshunds.
Disc protrusions (Hansen type II)
Herniation of the disc occurs more gradually and uniformly with this type. Type II protrusions are commonly accompanied by arthritic changes in the vertebral joints. Type II IVDD usually tends to progress over an extended period, rather than having an acute onset, and therefore can cause chronic compression of the adjacent spinal cord.
Type II disc degeneration is commonly diagnosed in middle-aged to large breed dogs (for example, Doberman pincer, German shepherd dog).
What are the clinical signs of intervertebral disc disease in dogs?
If disc herniation occurs, dogs may show signs of acute hindlimb paralysis or severe weakness. If the herniation is mild, dogs may only show signs of incoordination (ataxia) and pain but as more spinal cord damage occurs, weakness will progress and eventual paralysis can occur. With Type I intervertebral disc disease in dogs, symptoms are often acute with severe pain, weakness, and possibly paralysis of the hindlimbs. With Type II intervertebral disc disease, signs may be more subtle with gradual onset of pain, ataxia, and weakness.
How is intervertebral disc disease diagnosed in dogs?
A definitive diagnosis of IVDD can be challenging for your veterinarian as regular, survey spinal radiographs may not reveal the herniated or slipped disc. In some instances, there will be noticeable changes on the survey spinal radiographs but if the spinal radiographs are normal, it does not rule out intervertebral disc disease. If your veterinarian suspects IVDD, a prompt referral for advanced imaging such as an MRI, CT, or myelogram should be considered. The sooner your dog is diagnosed properly, the sooner it can receive treatment.
What are the treatment options for intervertebral disc disease in dogs?
The most important factor in the management of IVDD is early diagnosis. Surgical therapy is recommended for animals suffering from persistent pain, discomfort, or weakness that are not responding to the treatment; are paralyzed; have lost recent deep pain, or have rapidly advanced symptoms despite timely treatment. The most common decompressive surgical procedure for the spin is a hemilaminectomy which allows for the removal of the herniated disc material.
Dogs that are still ambulatory, (can still walk), have mild pain and slight neurological deficits otherwise, medical management and supportive care can be implemented. Typical therapy would include either non-steroidal anti-inflammatory drugs OR corticosteroids, pain medication, and muscle relaxants. For at least two weeks, a cage rest or complete confinement with no jumping is advised to avoid activity that may cause more disk material to herniate.
What is the prognosis for dogs with intervertebral disc disease (IVDD)?
Animals with a good pain sensation in the affected limbs and weakness usually have a favorable prognosis. When animals are paralyzed or their deep pain sensations are reduced, surgical intervention is required for recovery. If surgery is not possible, medical therapy may be considered as an alternative.
In summary, with intervertebral disc disease in dogs, intervertebral disk material can protrude into the spinal canal. This is a common occurrence that typically affects middle-aged to large-breed dogs by 3-6 years of age and causes pain or weakness. If you suspect your dog has IVDD, it’s important to see a veterinarian for advanced imaging such as an MRI or CT scan to confirm the diagnosis before treatment begins since this condition cannot be detected on regular survey spinal radiographs. The most common surgical procedure used for animals with intervertebral disc disease is hemilaminectomy which removes herniated disc material from the spine and relieves pressure on surrounding nerves so your dog can begin recovery more quickly. With proper care, the prognosis for animals with IVDD is typically favorable. If your dog experiences severe paralysis, immediate surgical intervention is necessary for the best possible outcome. Remember, early diagnosis is key to successful treatment!