Intervertebral Disk Disease (IVDD)
By Emily Hoppmann, DVM
In animals, as in people, the spine is the part of the skeleton that extends from the skull to the pelvis and the structure is like a two-tiered bridge. The upper level of the bridge contains the spinal cord, made up of sensitive nerve fibers that carry information between the brain and the rest of the body— especially the limbs; while the lower level is composed mainly of bones that are connected to each other by the intervertebral disks that act as shock absorbers. Inflammation affecting the spinal column and nerves is a fairly common issue that we see and the combination and stepwise process that includes intervertebral disk degeneration, bulging, and extrusion/rupture is called intervertebral disk disease or IVDD.
If a disk herniates or bulges, it pushes into the nerves and/or spinal column. This is typically a sudden and very painful occurrence that results in inflammation of the surrounding spinal cord. The symptoms that result depend on how much of the spinal cord or nerves are affected and how deeply the spinal cord is affected by the inflammation. This can be influenced by the time frame before starting treatment and location of the injury. With disk disease, time is critical so seek immediate medical attention if you suspect an issue.
Early detection, diagnosis, and treatment have a huge impact on recovery. The longer your pet has inflammation causing issues without receiving treatment, the less likely they are to make a full recovery. IVDD is common in dogs and uncommon in cats. There can be acute disease that results in sudden signs or chronic disease that results in signs that appear more subtly over several days to weeks. Often times you will see signs following some type of trauma, such as a fall, or after playing too rough. If you see any of the following clinical signs, you should seek immediate veterinary care: reluctance to move or stand up, back pain or a hunched back, crying or whining when being petted or moved, a “drunken” type walk (where the front legs and back legs do not appear to be moving in the same way), weakness or paralysis in the hind legs, loss of bladder and/or bowel movement control (or a lack of being able to urinate), a reluctance to move the head in certain directions, or a decreased appetites. Failure to act quickly with appropriate treatment, whether it is medical or surgical, can result in permanent consequences, including paralysis.
You can think of the spinal cord or nerves as having three layers with the outer layer being the first affected and the inner layer the last. The outer layer is responsible for the brain being able to tell where parts of the body, especially the legs, are located. The middle layer is responsible for the brain being able to tell the body how to move normally. The inner layer is responsible for the brain being able to receive the correct signals of deep pain occurring in areas of the body. With more mild cases, when it is just the outer layer affected you will see clinical signs such as pain, weakness, dragging the paw or standing on the wrong side of the paw. In these cases, often times medical management and confinement can allow the inflammation to resolve and your pet return to normal activity. However, if the middle layer, which allows your pet to move his legs, or the inner layer, which allows your pet to feel pain, are affected you will generally see some degree of paralysis and this is a surgical emergency.
Dog breeds with short legs and a long body (known as Chondrodystrophic breeds) such as the Dachshund or Pekingese are prone to IVDD because their body shape adds chronic stress to the spine, and because genetically they have a higher occurrence of problems with cartilage degeneration, including the cartilage within intervertebral disks. These dogs most commonly have sudden symptoms, which can start at a young age (as early as a year of age). Normal activities can result in IVDD or sometimes there is some other inciting or traumatic event, such as jumping down from a bed or out of a car, which causes an intervertebral disk to rupture. Therefore, as part of preventing potentially harmful effects of IVDD, it is wise to always avoid letting dogs of these predisposed breeds jump in a way that causes strain on the spine. Other ways to avoid disk disease are keeping your pet at his ideal body weight through a proper diet and exercise routine and reducing the risk of traumatic events occurring by training your dog from a young age to avoid stairs by providing ramps in place of stairs and to elevated places in your home (such as the couch or bed).
IVDD can occur at any level of the spinal cord and the different locations of injury will result in different problems and particular symptoms. For example, IVDD higher up in the spine can result in weakness or paralysis in all four legs, but an injury between where the ribs stop and the pelvis starts may only affect one or both of the back legs and/or tail. Injuries between where the ribs stop and the pelvis starts are the most common and this usually results in clinical signs where the front legs are normal, but the hind legs and/or tail are affected.
To confirm IVDD over other spinal disorders and to determine the location of the lesional area, I collect a complete medical history from the owner (the symptoms observed, how long the symptoms have been present, whether any types of physical activity make them worse, whether the symptoms have affected other vital functions such as appetite, and so on), perform a complete physical exam and a specific neurologic exam. I may also need to run blood work to rule out other diseases and make sure medications are safe, as well as take digital radiographs to see abnormalities of the spine, such as compression of the disk space or mineralization (though radiographs do not show the spinal cord, an MRI or CT scan is needed to visualize the spinal cord itself). All of these things will help identify the location and severity of the problem(s) and help guide treatment options, whether medical or surgical or a combination of both.
Treatment options vary according to the severity of the injury and are based on your pet’s symptoms, the physical examination results, and the results of any additional testing. Sometimes referral to a specialist is needed for more advanced cases when an MRI or CT scan is needed or if medical management is not an option. If there has not been any loss of motor or deep pain, medical treatment and confinement is often the chosen therapy. Every case is different and our treatment is individualized for each patient, but medical management generally consists of anti-inflammatory medication; however, muscle relaxants, and pain medication specifically targeted at the nervous system. An equally important part of medical management is confinement, since without confinement no amount of medication or time will allow the injury to heal correctly. Sedatives can be prescribed as needed to allow for proper rest and to avoid placing any unnecessary stress on the injured area. Strict cage rest means no activity at all and you will need to offer support or carry your pet up/down stairs when he needs to go outside to go to the bathroom. He must be on a short leash when taken outside to go to the bathroom and that is essentially all the activity that is allowed. It generally takes six to eight weeks to fully recover and periodic rechecks are needed. If your pet is too active before the full recovery period, he could re-injure himself – meaning you have to start over at square one, or worse, the injury could be more severe the second time around and surgical intervention may be needed. If at any point your pet gets worse during medical therapy, please seek veterinary attention right away to see if medical management is still an option and the treatment plan just needs to be adjusted, or if your pet now requires surgical intervention and not just medical management.
In more severe cases, in pets with repeat episodes, or if medical management is not successful, surgery will be required. The goal of surgery with a ruptured disk is to remove the ruptured disk material from around the spinal cord and allow the spinal cord to return to its normal location. With chronic disk protrusion the goal of surgery is to remove a part of the bone to allow the spinal cord to move around the disk more freely. You will still need to restrict your dog’s activity for several weeks after surgery and sometimes physical therapy is needed.
With this disease, neither medical management nor surgery guarantees a full recovery, so there is a chance that the IVDD will result in permanent spinal damage. This can include anything from just minor weakness in one of the limbs to full paralysis of the hind or all limbs and/or loss of bladder or bowel control. It is impossible to accurately predict the outcome since each dog is an individual and vary tremendously in their ability to recover. In some severe cases, the only way to know for sure whether recovery is possible is to proceed with treatment and nursing care and to observe any progress over the subsequent months after intervention. It is important to remember that you are not alone and we are here to help you every step of the way!