other names: IVDD, disc herniation/rupture, slipped disc, pinched nerve
Overview
Intervertebral discs are located in between the bones of a dog’s back and neck. Intervertebral discs normally act as cushions or “shock absorbers” to prevent the bones of the spine from coming in contact with each other, which could cause discomfort. There are two components of an intervertebral disc: an inner gelatinous part (nucleus) and an outer fibrous part (annulus). Conceptually, you can think of intervertebral discs as jelly donuts, with the inner jelly representing the nucleus, and the outer dough of the donut representing the annulus. Above these intervertebral discs is the spinal canal, which houses both the spinal cord and nerve roots. These are incredibly important structures that link the brain and the legs, allowing our pets to walk and go to the bathroom normally.
Causes
Intervertebral disc disease (IVDD) is an inherited degenerative condition that starts very early on in life (before 2 years of age). In this degenerative process, the intervertebral disc hardens and loses its “shock absorbing” abilities. This progressive weakening of the intervertebral discs causes a stiffer and more fragile spine long term. It is important to note that disc degeneration occurs in the majority of the discs of the spine, not just one disc. Intervertebral disc disease is the most common spinal cord disease in dogs.
Just because an intervertebral disc becomes degenerated, doesn’t mean that it causes a noticeable problem with our pets. We see signs and symptoms when a disc ruptures or bulges out and compresses the spinal cord and/or nerve roots in the spinal canal. There are different types of IVDD that cause clinical signs in dogs, with the following two being the most common:
Extrusion of the inner nucleus – This occurs when the inner “jelly” ruptures out of the outer donut into the spinal canal. Dogs with this condition most commonly present suddenly and have more severe dysfunction and pain. This most commonly affects younger (age two to seven years) and smaller breed dogs, although dogs of any age or breed may be affected.
Protrusion of the outer annulus – This occurs when the annulus, or the outer covering of the donut, slowly bulges or protrudes upward, putting pressure on the spinal cord. Dogs with this condition progressively get weaker over a period of weeks to months. This most commonly affects older (age six and older) and larger breed dogs.
It is important to note that a dog may suffer from both of these types of disc disease.
Clinical Signs
The clinical signs of IVDD are highly variable and often depend on a combination of factors, mainly the severity of spinal cord compression and bruising injury from initial herniation/rupture. The severity of signs can present as the following, from least to most severe:
- Back or neck pain (not seen in all patients)
- Wobbliness, stumbling, or dragging their paws when walking
- Inability to walk/support themselves without assistance, but still able to move their legs
- Paralysis or inability to move their legs at all (often unable to urinate unassisted)
- Paralysis and inability to feel their legs when pinched (unable to urinate unassisted)
The connections from the brain to the spinal cord is a “downhill” system. What that means is if a dog has disc disease in their neck, all four legs can be affected. If a dog has disc disease in the middle of their back, only the back limbs can be affected. In general, dogs with IVDD in their neck most commonly just have pain, while dogs with IVDD in the middle of their back tend to have more neurological dysfunction (e.g. difficulty walking and urinating).
Diagnosis
An MRI is the diagnostic of choice to confirm the diagnosis of IVDD, determine the severity of the disease, and direct the appropriate treatment. In select cases, a CT scan can be used in place of an MRI.
Treatment
Intervertebral disc disease can be treated either medically or surgically. Recommendations on which to choose depends on a variety of factors, including the severity of the neurological dysfunction, severity of pain, MRI/CT findings, and/or lack of response to previous therapies.
Medical treatment consists of pain medications and strict rest for two to four weeks. Anti-inflammatory medications (steroids or NSAIDs) and/or acupuncture are sometimes added to the conservative treatment plan as well. Medical therapy is often recommended for dogs with manageable pain, mild wobbliness when walking, and/or more chronic conditions (disc protrusions). The hope with medical therapy is that the body will “heal itself” or “adapt” to the disc rupture or bulge.
Surgical intervention involves drilling a window in the bones of the neck or back and removing the disc material that has ruptured or protruded into the spinal canal. This relieves the compression on the spinal cord and nerve roots. An MRI or CT is always needed prior to surgery to help direct the surgical approach. Surgery for confirmed IVDD is recommended for dogs that cannot walk by themselves, have severe pain, or have failed medical therapy.
After surgery, recovery entails a month worth of STRICT cage rest to allow them to heal from the surgery and to minimize any post-operative complications.
Prognosis
Prognosis for IVDD depends on a variety of factors, most significantly the severity of neurological deficits at original examination and the type of disc disease (extrusion or protrusion).
Dogs with Disc Extrusions
Medical treatment: The response to therapy is variable, but often favorable if neurological deficits and pain are mild. However, relapse of neurological signs is higher with conservatively treated dogs. Despite appropriate medical treatment, progression of neurological signs may occur, and surgical intervention may be recommended.
Surgical treatment: Dogs that present with the ability to still feel their legs when pinched, even if paralyzed, have a good to excellent prognosis. The ability to walk and urinate unassisted occurs in approximately 90-95% patients. Return to walking may take a few days to weeks, and often depends on the initial severity of neurological injury. Mild wobbliness may remain, but this should not affect their quality of life.
Unfortunately, prognosis for dogs without the ability to feel their feet have a much worse prognosis. With surgery, the chance to return to walking and urinating unassisted is approximately 50%. This means that there is a 50% chance of managing a paralyzed and urinary incontinent dog for the rest of their life. If some recovery in neurological function is seen, it often occurs in the first two weeks after surgery.
Dogs with Disc Protrusions
Dogs with disc protrusions are most commonly treated medically, although in some cases, surgery is recommended. Return to completely normal neurological function is unlikely, regardless if medical or surgical intervention in pursued. The goal is often to prevent continued neurological deterioration, as opposed to expecting significant neurological improvement.
It should be noted that recovery for dogs with disc protrusions is often more variable and initial yet transient deterioration in neurological ability after surgery is common. Recovery is often lengthy (weeks to months) and professional physical therapy is often highly recommended.
Reoccurrence & Prevention
As stated previously, IVDD is a disease of all of the intervertebral discs of the spine, not just one disc. Regardless if surgical or medical treatment is pursued, reoccurrence of neurological signs and pain can occur due to a herniation at the same or a different intervertebral disc. If surgery is pursued, reoccurrence rate is approximately 10-15%. If surgery is not pursued, relapse rate is approximately 50%. Reoccurrence of neurological signs may be less or more severe compared to the initial injury and may occur days to years after initial injury.
There are preventative measures that are recommended to reduce the risk of further disc disease. Some of these are easier to accomplish than others.
Chest harness – Dogs with IVDD should never be walked with a leash attached to a neck collar. As there are intervertebral discs in our neck, continued or excessive pulling at a neck collar can worsen IVDD in the neck. Instead, chest harnesses transfer the force to the chest and away from the spine, eliminating the stress on the neck. Many options are available and can be purchased online or at a pet store. Identification and rabies tag on a neck collar that are not attached to a leash are ok.
Weight management – Dogs that are overweight are at a higher risk of IVDD. Increased weight places more stress and strain on the spine, worsening this disease. Ideally, patients with IVDD should be on the slender side. As a general rule of thumb, the last one or two ribs should be visible.
Decreasing high impact exercise – This is often the most significant contributing factor to IVDD reoccurrence and the most difficult to eliminate. Although we would like to eliminate the following activities entirely, sometimes this is impossible. However, significantly reducing the following activities is extremely important to diminish the likelihood of a reoccurrence of IVDD signs.
- Jumping – The majority of dogs present after jumping down off of furniture, retaining walls, etc. The most significant way to curb this is simply training and avoidance. Dogs with IVDD should not be allowed on the furniture. When not supervised, dogs should not be in rooms where they are not able to jump up or down off of beds or couches. Although ramps or stairs to furniture could be considered, dogs will often walk up these but continue to jump off of the furniture, defeating the purpose.
- Rough housing – This should be avoided with other canine housemates or dogs at the dog park. Gentle playing is acceptable as long as it does not involve wrestling, tackling, or jumping.
- Tug of war – This should be avoided to prevent IVDD in the neck.
- Acceptable exercises
- Swimming – This is highly encouraged as swimming is a low impact exercise that maintains muscle and joint strength but minimizes the stress on the spine.
- Walking & running – Once rest and recovery from the initial IVDD injury has occurred, a gradual return to walking and running should occur. Long term, these exercises should be done in moderation and avoid jumping.
- Stairs – Going up and down stairs is allowed UNLESS they do not physically take each step at a time. If they jump off the last few stairs when going downstairs, then stairs should be avoided.
Breeding – As IVDD is an inherited condition, breeding animals with IVDD should be avoided to decrease the likelihood of further generations from experiencing the same physical and emotional stress of a pet experiencing IVDD symptoms.