Hi there! Today we are going to start a conversation on a condition of dogs (and occasionally cats!) called Intervertebral Disc Disease.
Intervertebral Disc Disease
Intervertebral disc disease, also known as IVDD, is a relatively common cause of back pain, difficulty walking, and even paralysis in dogs. You may have heard people say their dog has a bad back or a slipped disc – most likely they are describing this condition.
I have frequently introduced owners to this condition in my life as an ER veterinarian. Let’s use that conversation to work our way through the big picture discussion of IVDD. In future lessons we will dive into this condition to greater depth.
Types of IVDD
There are actually two main types of IVDD. This lesson will focus on Type 1, which affects mainly small breed dogs starting early in adulthood. We will talk about Type 2, which affects geriatric large breed dogs, in a different lesson.
Clara Visits the Vet
The Patient
Dachshunds are the poster child for IVDD. Dogs with long backs and relatively short legs are commonly affected. This includes brachycephalic dogs (French Bulldogs, English Bulldogs, Pekinese, Shih Tzus), Corgis, Bassets, and Beagles. Keep in mind that many dogs not on this list can develop IVDD as well!
Let’s say today’s patient is a 5 year old female spayed miniature Dachshund named Clara.
The History
Clinical signs can start gradually or abruptly. These signs can be stable or can progress. Two weeks before presentation, Clara’s appetite and energy level decreased. Her owners noticed that her back was more hunched than normal, but she seemed to be getting around okay. Then, this morning, Clara started stumbling when she was walking around the house and was having much more trouble getting around. This abrupt change led to her owners bringing her in to be examined. Clara has never had any problems like this before. She is a very active dog and loves running around and jumping off of furniture.
The Exam
The physical exam helps to determine the degree of neurologic changes; this exam may include a standard physical exam, an ambulatory (walking) exam, and a special neurologic exam. Clara’s exam identified pain in her mid-lumbar (“lower”) back. When the skin behind the localized area of pain is pinched, it twitches along both sides of her back. When walking, Clara crosses her hindlegs when she takes steps and the toenails on Clara’s hind feet can be heard to scuff – and there is wearing of the top of the nails on exam. When Clara’s front feet are turned over so she is standing on the top of her paw she immediately flips the paw into its normal position; when her hind feet are turned over, she makes no attempt to flip the paw over at all.
The Conversation
Based on Clara’s breed, history, and physical exam findings she most likely has a condition called Intervertebral Disc Disease, or IVDD. This is a degenerative condition that is common in dogs like Clara. There are medical management options and surgical options.
What causes IVDD?
IVDD is caused by bulging of the disc into the space around the spinal cord. Think of the disc like a jelly donut, with a firm exterior and gelatinous core. When the “jelly” extrudes from the disc into the spinal canal it puts pressure on the cord. Different clinical signs can present depending on how much compression of the spinal cord there is.
What are signs of IVDD?
The information transmitted by the spinal cord is contained in different, specific areas. The exterior of the spinal cord contains fibers that are responsible for causing pain. This is why the first symptom of IVDD is often pain. As more of the spinal cord is compressed, signs develop in the following order.
- Loss of proprioception
Proprioception is the brain’s understanding of the body’s position in space. The test for this is often referred to as conscious proprioception or CPs. This is the test where your dog’s feet are turned over. If the brain is communicating normally with the feet, the dog will immediately flip the feet back to their normal orientation. If the signal is delayed or disrupted, the dog will turn the feet over slower than normal – or as in Clara’s case, not turn the feet over at all.
– - Loss of motor function.
Signs of loss of motor function include weakness (also called paresis.) This causes abnormal walking – ataxia. Complete loss of motor function means a dog cannot move their legs at all. Clara’s ataxia – a sign of decreased motor function – include her difficulty walking around, her scuffed nails, and the crossing of her feet when walking.
– - Loss of cutaneous sensation/superficial pain.
When superficial pain sensation is lost, a dog may not notice when you lightly pinch the affected toes. Another test for loss of cutaneous sensation is called the Cutaneous Trunci reflex. When the skin on the back is pinched, a normal CT reflex causes twitching of the muscles under the skin on both sides of the spine cranial (towards the head) from the location pinched. Clara’s CT reflex was normal.
– - Loss of deep pain.
The fibers of the spinal cord that transmit deep pain sensation are carried deep within the spinal cord. Deep pain is tested by pinching the toes of the affected limbs very hard, to see if there is a conscious response (dog looks at you or vocalizes) or withdrawal of the limb. This test is not performed if any of the previous levels of dysfunction are normal. Because Clara still had motor function, so this test was not performed.
How is IVDD treated?
Treatment for IVDD usually falls into one of two categories: Medical (or conservative) Management and Surgery.
Medical Management can include medications for pain, inflammation, and muscle spasm; activity restriction (sometimes called “cage rest”); acupuncture, laser therapy, and physical rehabilitation. This option is most appropriate for dogs who still have fair to good motor function, whose signs are new, and/or who have never been treated for their signs before. Because Clara fits all of these categories, she is a good candidate for medical management.
Surgical treatment – called a hemilaminectomy allows the compression on the spinal cord to be relieved. Advanced diagnostics such as CT (a “CAT scan”) or MRI are required to allow the surgeon to know where the abnormal disc is. Surgery is most commonly performed on dogs that have had recurrent issues, progressive issues despite medical management, or are deep pain negative. Clara is a candidate for surgery, but an attempt at medical management first would also be appropriate. If Clara’s owners are leaning towards surgery, they will be referred to a specialist Neurologist.
Clara’s case – Let’s discuss medical management
Clara is a good candidate for medical management. She is deep pain positive and has never been treated for this condition before. The idea behind medical management is that medications are administered to treat discomfort while high-impact activity (such as running, jumping, and rough play) is minimized to allow the bulging portion of the disc to scar so that the compression of the spinal cord does not worsen. Ideally, dogs like Clara with a predisposition for disc issues, will be prevented from activities which are hard on the discs (like jumping from furniture!) for the rest of their lives.
Activity Restriction
Although this period of activity restriction may be referred to as “cage rest,” it is no longer recommended that dogs be completely confined. This is because activity restriction should be enacted for 4-6 weeks, and complete confinement can result in significant muscle atrophy.
During activity restriction, a dog should be confined to a small space (such as with baby gates) or a single room. They should not be able to access stairs and must be prevented from getting up and down onto furniture. You should also consider things like how they respond when someone knocks or rings the doorbell – if they are inclined to jump up and run towards the sound, this stimulus should be prevented as possible.
Medications
Medications prescribed during medical management are intended to increase comfort and reduce inflammation. This may include a pain medication (such as Gabapentin or Tramadol), a muscle relaxant (such as Methocarbamol), and a medication to reduce inflammation (an NSAID such as Rimadyl or a steroid such as Prednisone.)
Additional treatment options
Additional treatment options should be strongly considered to add to both medical management or post-surgical treatment. These include:
Acupuncture: great for treating pain and decreasing neurologic deficits.
Physical Rehabilitation: great for maintaining strength and learning safer ways to move.
Ultimately the decision about whether to try medical management or move directly to surgery can be intensely personal. Some owners opt to forgo surgery unless their pet’s independence is severely affected. Other owners opt to pursue surgery at the earliest opportunity.
Check back for our next lesson, where we will discuss some of the ins and outs of surgical management of IVDD. Thanks for reading!
