Stress (either one powerful stress or multiple stresses over time) can cause the discs to bulge/swell or even rupture
Disc material can compress and/or traumatize the spinal cord and/or nerve roots via high-speed impact
Intervertebral Disc Disease (IVDD) refers to bulging/rupture of the discs, causing problems in the spine and/or nerve roots
Who can be affected?
Dogs are affected more commonly
Chondrodystrophoid (short-legged & long-backed) dogs are most commonly affected.
- Dachshund most commonly (over 50% of cases), but also Lhasa Ahpso, Shih Tsu, Pekingese, Beagle, Basset Hound, etc.
- Discs degenerate and rupture at an early age (radiographic/x-ray signs seen as early as 2 years)
- 3-6 years old most common, but can present at younger, as well as older ages
Other breeds, such as the Labrador Retriever, usually present at a later age, average 5-12 years old
Cats can suffer from disc disease as well.
What are the signs?
The signs relate on the location and degree of the disc disease
- Disc disease typically affects the site of compression and the spinal cord behind (towards the tail) that spot
- Thoracolumbar (mid-back) discs are most commonly affected. The front legs and neck are commonly normal/unaffected, with signs affecting the back and back legs
- Cervical (neck) discs affect the neck as well as all 4 limbs potentially
- Lateralizing (off to the side) disc compressions sometimes affect the side of compression more severely, especially if a nerve root is compressed (as with sciatica)
Progression of signs
As compression worsens, the signs get worse, generally in this order
- Crying out in pain
- Refusing to turn or bend the head/neck
- Walking with a hunched back
- Reluctance to walk, run, or jump
- In a lateralized compression towards the back/bottom of the neck or towards the lower back, pets will often show severe pain in single limb - looks like an orthopedic problem.
- Sometimes described as walking like a "drunken sailor"
- Scuff their toes as they walk
- Standing on the top part of their foot
- Crossing-over the left and right limbs
- Stumbling and falling to the side.
- Weakness/loss of ability to walk
- The pet can move the affected limbs, but is no longer strong enough to support weight.
- Loss of motor ability - paralysis
- Pets are unable to move the affected legs.
- Around this time, pets also lose the ability to voluntarily urinate.
- They can only urinate when their bladder becomes so full that its pressure exceeds the strength of the urethra holding it.
- The pets will be dribbling constantly unless they are catheterized or manually emptied.
- High risk of urinary tract infection or even bladder rupture
- Loss of sensory ability (sensation/feeling)
- Pets are unable to feel the toes in the affected legs.
- It is important to realize that withdrawing a pinched toe is purely a nerve reflex and does not indicate spinal function.
- The pet must be consciously aware of the pain test, such as turning their head to look at the stimulation, vocalizing, etc.
- If compression is severe and/or occurs rapidly, the pet may go from normal to paralyzed (potentially without sensation) almost instantly
What else could be causing these signs?
Sometimes orthopedic problems can be confused with back problems. For example, bad hips or two bad knees might look a lot like a dog that is weak from back pain. Your regular veterinary can examine your pet and refer him or her to a board-certified specialist as indicated.
For spinal cord disease, while ruptured intervertebral discs are the most common (especially in a dachshund or similar breed), other possibilities include:
- Fibrocartilaginous Embolic Myelopathy (also known as "FCE")
- This relates to a small portion of the disc getting into and obstructing an artery supplying the spinal cord.
- There is not spinal cord compression, and surgery is generally not indicated, but advanced imaging is required to rule out compressive disease.
- Although you might expect a tumor to cause slowly progressive signs, sometimes a pet will compensate for the slowly growing mass, and then a sudden sharp turn or something causes the cord or the tumor to swell somewhat, and causing a rapid decompensation.
- Similarly, while you might expect tumors in older pets, they can sometimes occur in the very young.
- Some types of tumors will show up on plain x-rays, but generally advanced imaging (CT or MRI) is required.
- These typically require a major impact, such as being hit by a car, falling down the stairs, having a large object (or person or other animal) fall on the pet, or an attack by another animal.
- Infection of the disc causes swelling and inflammation that can lead to similar signs.
- This can often be seen on plain x-rays, but sometimes requires advanced imaging.
- Generally not the typical bacterial meningitis that is contagious and potentially fatal
- Often either immune-mediated, viral, or another infectious disease.
- A spinal tap can usually diagnose this definitively.
- Congenital anomolies - Birth defects.
- Bulldogs and similar breeds often have misshapen vertebrae in their back
- Toy breeds sometimes have defects in the first two vertebrae in their neck (atlanto-axial instability)
- Caudal Cervical Spondylomyelopathy (Wobber syndrome)
- Progressive thickening and compression of the vertebrae and discs in the neck, often associated with instability.
- Typically Dobermans or Giant breeds, such as Great Danes or Mastiffs
- Others - there are more, but -- while this may seem overly simplistic -- we typically see the most common problems most commonly. The work-up for disc disease will rule in or out most of the common problems. In the small percentage of cases where a diagnosis is not achieved, further diagnostics may be recommended at that time.
When should I take my pet to a veterinarian
- Back or neck problems can often progress/deteriorate rapidly.
- The prognosis gets worse and/or the length of time required for recovery gets longer with worsening signs.
- Generally, you should contact your veterinarian and be seen as soon as you notice signs.
- You may need to take your pet in to an emergency clinic.
What tests are done?
- General health screening
- Complete blood count - assesses red cell, white cell, and platelet counts; screens for anemia, systemic infection, inflammation, and some other disorders
- Serum chemistry - assesses liver and kidney values, blood sugar, electrolytes, calcium, etc.
- Urinalysis - screens for infection, early kidney disease, etc.
- Survey radiographs (x-rays)
- Plain x-rays can show mineralized discs and collapsed disc spaces, but these findings do not necessarily correspond to the site of the current problem.
- Evaluating plain x-rays alone can be misleading in 40-50% of the cases.
- Also allows screening for cancer eating into the bone or infection in the disc space (discospondylitis)
- Cannot directly see the spinal cord or disc material that is not mineralized.
- Requires heavy sedation or light anesthesia to prevent patient positioning from distorting findings, leading to false negatives and false positives
- Radiographs (x-rays) taken following injection of an iodine containing compound into the spinal fluid
- Outlines the spinal cord and allows evaluation of external compression of the spinal cord or internal swelling of the cord
- Injection can be cisternal (top of the neck) or lumbar (near the pelvis)
- May need to do both injections if swelling around spinal cord is sufficient to prevent passive movement of contrast agent around the site of compression.
- Can be 95% diagnostic in terms of localizing the affected disc space(s).
- Often difficult to determine whether lesion is right- or left-sided, which can lead to a more extensive surgery.
- When combined with CT, the diagnostic ability is much improved, including definitive localization and lateralization (determining whether the problem is left- or right-sided)
- Allows less extensive and more definitive surgery
- Computed Tomography (CT/CAT scan)
- Three dimensional x-rays generated with computer assistance.
- Removes the overlapping of tissues and allows more direct visualization of the spinal canal
- Very rapid evaluation...can image the entire spine from neck to pelvis in minutes
- Best if done in conjunction with a myelogram - the same injection is performed, but the 3D evaluation granted by CT gives much more distinct visualization, as well as determining right vs. left location
- Allows less extensive and more definitive surgery
- Spinal fluid analysis
- A sample of cerebrospinal fluid is taken prior to injection of the myelographic contrast agent
- Cytology - microscopic analysis, checking for inflammation, infection, cancer, etc.
- Culture - checking for infection, identifying any bacteria present and determining to what antibiotics that bacteria is sensitive
- Magnetic Resonance Imaging (MRI)
- Allows excellent visualization of spinal cord without need for myelogram
- High-field magnets (3-5 Tesla) as used in many universities and in some referral practices provide high-quality diagnostic images in a relatively short time period.
- Low field magnets (0.2 - 0.3 Tesla) are the only ones in Brevard County and in most specialty practices. These produce low quality images, and the studies may take an hour or more to image a few inches.
What are the treatments?
- Medical treatments
- Non-steroid anti-inflammatory drugs (NSAIDs), such as Metacam/Meloxicam, Previcox, Deramax, Carprofen, and even aspirin
- Generally minimally effective against spinal pain.
- They are effective for chronic spinal arthritis pain, but much less so for nerve root and/or spinal compression.
- Further, they have almost no effect on spinal cord swelling or inflammation (meningitis)
- Do not help with spinal cord compression.
- Steroids, such as prednisone
- Can be very effective for spinal and nerve root pain as well as helping with spinal swelling and/or inflammation.
- However, it is important to realize that in pets they will not reduce spinal cord compression caused by disc bulging or rupture.
- Your pet may feel better and be more active, leading to another traumatic spinal event that could result in paralysis or even loss of feeling.
- Additionally, as steroids will decrease inflammation, they could hinder the changes of diagnosis of meningitis or certain types of cancer if they are started prior to spinal fluid evaluation.
- Generally, I recommend performing the tests before starting steroids.
- Muscle relaxants, such as Methocarbamol/Robaxin
- Can be helpful with pain caused by muscle spasm associated with nerve root and/or spinal compression.
- May also cause some level of sedation, which can be beneficial in helping with confinement/exercise restriction
- Alternative therapy
- Acupuncture can be very beneficial in pain relief, although it will not actually relieve the spinal cord or nerve root compression
- Rehabilitation ("physical therapy") is very beneficial to help strengthen the muscles in a pet. As it will not relieve spinal cord compression, I typically recommend rehab AFTER surgical decompression.
- Chiropracty can be helpful for pain relief, but is potentially extremely dangerous when you have disc disease causing spinal cord compression.
- Manipulation of a compressed spinal cord without relieving the compression could severely worsen the clinical signs and possibly cause even more disc to herniate. This could lead to paralysis or even loss of feeling.
- Surgery is required to remove material compressing the spinal cord.
- Failure to remove such material leads to ongoing spinal cord compression and progressive and potentially permanent spinal cord damage.
- For problems in the back, a hemilaminectomy is typically performed.
- A window is made in the bone towards the bottom of the spinal cord, so disc and other compressive material can be removed.
- Requires knowledge of the exact intervertebral disc space AND the side affected.
- Best determined by a CT/myelogram combination or high field MRI
- For problems in the neck, based on the specific location(s) of compression, there are different options
- Requires knowledge of the exact intervertebral disc space AND whether the compression is central or lateralized
- Best determined by a CT/myelogram combination or high field MRI
- A ventral slot is performed when there is compression directly underneath the spinal cord over the disc space. This is approached from the bottom of the neck
- A dorsal laminectomy is performed when the compression is significantly lateralizing (off to the side too far to get with the ventral slot) and/or not located over the disc space.
- Patients with strongly lateralizing compression often have sharp nerve root pain and a front leg lameness (referred to as a root signature).
- For multiple sites of centrally ventral compression, some surgeons prefer to perform a continuous dorsal laminectomy rather than multiple ventral slots.
- If there is both ventral spinal cord compression and significant lateralization, it is a judgment call of which approach to perform.
- In many cases, removing the ventral spinal cord compression will provide significant relief that other signs can be managed medically
- In some cases, however, both surgical approaches (usually staged some time apart) may be indicated to completely relieve signs.
How will my pet do?
- Conservative/medical management
- If there is spinal cord compression, there is roughly a 50% chance that your pet will recover with medical management.
- The more severely affected your pet is, the worse the prognosis for recovery.
- More severely affected pets also have a potentially narrow for treatment
- The longer a pet is unable to walk, the greater the risk of permanent damage
- If a pet loses the ability for conscious awareness of pain (not to be confused with a simple withdrawal reflex), prognosis for recovery is guarded and worsens with every passing hour without surgical decompression.
- Surgical management
- With acute spinal cord compression, as long as a pet retains feeling in the toes, 90-95% of pets will go on to a functional recovery.
- There may be some degree of weakness (one side may be worse than the other), like a stroke victim, but most pets can walk, run, play, and are both continent and comfortable.
- Small dogs (< 20 lbs.) that lose the ability to walk but can still feel their toes take an average of 2 weeks to be back up and walking
- Bigger dogs that lose the ability to walk but can still feel their toes may take closer to 12 weeks to be back up and walking
- Many patients are neurologically worse right after surgery
- If a pet cannot walk after surgery, he or she also may not be able to urinate without assistance.
- Manual expression - externally squeezing the bladder to empty it
- Urinary catheterization
- Walking assistance
- Rehabiliation exercises
- Unfortunately, even 95% means that 5% of pets will not recover well
- Permanent paralysis
- Chronic pain, especially if there was both spinal cord and nerve root compression in the neck, for example
- Ascending myelomalacia
- Rapid and progressive spinal cord destruction leads to progressive paralysis in all limbs and the chest, leading to death from inability to ventilate/breath effectively.
- For patients with chronic compression, the prognosis is much less predictable
- Testing only reveals the site and degree of compression, not the level of spinal cord damage.
- If a pet has had previous back problems that were managed medically, or if the back problems have persisted for weeks to months, the cord may already be severely damaged.
- There is a greater chance of a poorer outcome, including paralysis and/or loss of feeling following surgical decompression in a chronic case.
- For these reasons I strongly recommend advanced imaging of the spine rather than just seeing if a pet will get better initially on steroids.
- For patients that have lost feeling in the toes (often referred to as loss of deep pain), the prognosis for recovery varies between 5-50% and is more likely to be closer to 12 weeks or more to be back up and walking if the pet does recover.
- Even with permanent paralysis of the back legs, most pets are happy and comfortable, and can do very well in a cart.
What if I decide to "wait and see" how my pet does on medical therapy, etc. before considering surgery?
- Many pets improve significantly and seem to show a full recovery on steroids
- Spinal cord compression generally does not go away, so even if your pet is not showing signs, the cord is likely being continually compressed and possibly undergoing permanent damage
- Because the steroids make the pets feel better, they tend to be more active, which is very dangerous. They are at a high risk to herniate more disc material and/or cause more spinal cord swelling, causing acute paralysis and/or potentially the loss of sensation (temporarily or permanently)
- If your pet relapses in the future, instead of having a 95% chance of recovery, the chances are more likely to be 50-75%, with a greater risk of permanent paralysis.
- For these reasons, I strongly recommend advanced imaging of the spine before deciding on surgery vs. conservative/medical management.
Please schedule an appointment with our board-certified surgeon, Dr. Jeff Christiansen at the clinic of your choice, to evaluate your pet and to discuss options to improve your pet's or patient's length and quality of life. Back or neck problems can often progress/deteriorate rapidly. Generally, you should schedule as soon as you notice signs. You may need to take your pet in to an emergency clinic. From Island and Aloha, Dr. Christiansen can be called in as needed for emergency evaluation and therapy.
For after-hours emergencies, please contact the Animal Specialty and Emergency Hospital in Rockledge (321 752-7600) or Treasure Coast Animal Emergency and Specialty Hospital in Vero (772 569-4500).
Check here for a more complete list of conditions treated.
If you have additional questions, please feel free to e-mail Dr. Christiansen directly.