consensus statement IVDH in dogs
Can Paraplegic Dogs walk?
What do we know about the natural progression of thoracolumbar intervertebral disc extrusion (TL-IVDE) in dogs? We have been taught when a dog stops having voluntary movement of their pelvic limbs (paraplegia) they need surgery to recover the ability to walk, right? What about those that have lost deep pain? What if we didn’t do surgery – what happens to those dogs? A study was published in JVIM this year that looked at the natural progression of medically managed TL-IVDE in non-ambulatory dogs and evaluated not only the recovery rate, but also what the discs “did” on sequential MRI 3 months after starting medical management.
Results
Sixty-seven dogs met the inclusion criteria – 51 with deep pain, 21 without deep pain, 5 with signs of myelomalacia at presentation.
Treatment consisted of NSAIDs (steroids were discontinued and replaced with NSAIDs if started), pain management and physiotherapy.
· Recovery
· Dogs with deep pain: 96% regained walking and voluntary urination (49/51)
o Median time to recovery 11 days (7-21 days IQR).
· Dogs without deep pain: 63% regained walking and voluntary urination (10/21).
All dogs (regardless of ambulatory status on recheck) did not have signs of back pain on evaluation 3 months after enrollment in the study.
The change in compression on MRI was interesting. In some patients, the compression almost completely resolved, and for others there was less than a 5% change. This wasn’t correlated with clinical signs but looking at the figures it does not appear to have a direct relationship.
Key point:
If you have a patient presenting with acute, non-ambulatory paraparesis or plegia, surgery is a very reasonable first step. However, it isn’t the only option! Don’t euthanize unless myelomalacia is present!! Consider conservative treatment because we may end up with an ambulatory patient after 3 months! Just because an owner cannot afford an MRI or surgery, doesn’t mean we should do a neurology consult, either. 😊
Thanks for reading! I hope you’re having a good week and look forward to working with you soon.
The 5 Types of Disc Herniation (that we know of!)
The Five Types of Disc Herniation (that we know of!)
'Tis CE season so I thought it would be fun to pull up this old TidBit Tuesday from 2020 and refresh our memories about the different types of disc herniation that may be diagnosed in dogs. I hope you enjoy this light reading on your midsummers morning!
Dystrophic calcification secondary to chondroid degeneration of nucleus pulposus (NP), is called Hanson Type I. This causes mechanical stress on the outer annulus fibrosus (AF), leading to rupture of individual collagenous strands of AF and eventually full failure and extrusion.
Fibrous degeneration occurs when fibers of the disc split leading to accumulation of tissue fluid and plasma between the annular fibers. Over time the mechanical pressure exerted by NP causes thickening of the AF dorsally, causing protrusion. (Hanson Type II).
ANNPE (Acute noncompressive nucleus pulposus extrusion) - this is normal (probably) NP that is exploded into the canal, usually during high activity. Also called a traumatic disc herniation by some folks.
AHNPE (Acute hydrated nucleus pulposus extrusion) – An apparently normally hydrated NP that is compressive and often located ventral to the cord in the cervical spine.
There may be significantly more neuro deficits and less signs of cervical pain with AHNPE compared to other causes of cervical myelopathy.
FCE (Fibrocartilaginous embolism): a piece of material histologically similar NP that becomes dislodged and finds its way into the vasculature surrounding the spinal cord. This can be into venous or arterial blood vessels. The end result is an acute shift in blood flow at the level of the spinal cord.
Match the clinical sign with the type of disc herniation
A. Chronic, progressive ataxia progressing to paresis
B. Acute, non-progressive unilateral weakness affecting one leg, or one side (hemiparesis)
C. Acute, progressive, painful ataxia progressing to paresis in a chondrodystrophic dog
D. Acute non-progressive ataxia and paresis affecting both sides of the body (paraparesis or tetraparesis)
E. Acute, rapidly progressive tetraparesis and ataxia of all four limbs with minimal cervical pain
If you answered...
Type I: C
Type II: A
ANNPE: D
AHNPE: E
FCE: B
you are correct!
Based on the clinical picture, it can be very difficult to distinguish Type I from ANNPE, and AHNPE. Typically, type I is painful (but not always), and the other two are minimally to non-painful.
Which of these require surgery?
Any disc herniation that results in compression of the spinal cord with associated clinical signs could be considered for surgical correction. This statement would then suggest that Type I, Type II and AHNPE could be surgically corrected. Therefore, any patient with signs of a progressive or painful myelopathy should be evaluated for diagnostic imaging (typically MRI) for possible surgical intervention whenever possible.
Thanks for reading! I hope you have a wonderful week. As always, reach out if I can help you, help your patients, with neurologic disease.
Intervertebral Disc Herniation in Yorkshire Terriers
Yorkies are a popular, and common dog breed in the USA and I (we?) see them quite a bit in neurology referral practice. That said, I had never read that they were officially considered a chondrodystrophic breed. Apparently, they are!
Intervertebral disc herniation (IVDH) occurs with high frequency in chondrodystrophic dogs, but how often do we see it in Yorkies? According to a recent article, about 10% of Yorkshire Terriers with neurologic disease are diagnosed with IVDH and undergo surgical intervention.
How do Yorkies present with IVDH?
Cervical hyperesthesia only 5/60 (8.3%)
Ambulatory tetraparesis with or without neck pain (grade 2): 26/60 (43.3%)
Non-ambulatory tetraparesis or plegia with or without neck pain: 29/60 (48.4%)
No association with recovery and presence or absence of ambulation was found in this study. This is inline with other studies that have not found voluntary motor to be a prognostic indicator.
Acute signs in 80% of dogs
Chronic signs in the remaining 20%
Yorkies with IVDH instead of another neurologic disease were statistically heavier and older
How do Yorkies do with surgery?
Thankfully, quite well, according to this report. In this study, the majority (82%) had one IVDH, 15% had two and 3% had 3 IVDH site repaired. In my experience, Yorkies far exceed dachshunds for having multiple IVDH requiring surgery at the time of diagnosis. Could this be a difference in genetic pool (this study was conduced in Czechia, Slovakia and Hong Kong)? In this study, all dogs returned to ambulation at some point, post operative. Most were walking by hospital discharge, but not all. This is comparable to dachshunds.
Key Points
Yorkshire Terriers are chondrodystrophic and therefore predisposed to type I IVDH
Surgical intervention is likely to improve ambulation
Approximately 50% of Yorkies will be ambulatory, and 50% will not at the initial diagnosis.
Thanks for reading! I am leaving for ACVIM today (Tuesday June 13th) and will be out for the remainder of the week. I'm so excited to collaborate with colleagues and bring new knowledge back to the patients we share! If you need me, email is preferred but texting is also fine. I will have limited ability to answer the phone but will do my best to return your call in a timely manner. Please excuse any unusual delays! Have a great week!
Consensus Statement for Intervertebral Disc Herniation in Dogs, 2022
October, 2022... We have long known that intervertebral disc herniation type I (IVDH) affects chondrodystrophic dogs, at a young age, disproportionately compared to non-chondrodystrophic dogs. We also know that many dogs benefit from surgical and medical intervention. We also know that the neurologic examination is a major predictive factor on recovery (medical and surgical intervention). What we don't know, is how to put what we know into a digestible nugget for clients to hear and understand when in our exam rooms with a dog with suspected IVDH.
First things first... We diagnose IVDH with MRI, CT, CT-myelogram or just myelogram. We don't diagnose IVDH on plain radiographs, or on neurologic exam. (Sorry, soapbox here.) When I say a dog "with IVDH" I mean that they have undergone some sort of diagnostic imaging (MRI, CT, CT-myelography or myelogram) and have been found to have compression to the spinal cord from suspected or confirmed herniated disc material. Presumably, of type I nature for this TidBit. If we don't have diagnostic imaging, but have a chondrodystrophic dog (beagles are included in this group) with appropriate neurologic signs we can call it "presumptive or suspect IVDH". We should, honestly, discuss other differential diagnoses with clients to ensure they understand that there are other possible causes so their decisions are informed. Common diseases that can mimic IVDH could include (but are not limited to) meningomyelitis, neoplasia, Syringohydromyelia, discospondylitis, and spinal trauma/fracture.
Medical intervention... The cornerstone of medical intervention is bedrest for 3+ weeks, anti-inflammatory (typically NSAIDS, but some neurologists prefer steroids), and muscle relaxants or pain management, if the pet is painful. See below for the consensus statement recommendations for medical intervention.
Surgical intervention.... I think this one is self explanatory (mostly). One small point I'll make is that fenestration is not always included when discussing surgical intervention. I consider fenestration an important part of surgical treatment but it does NOT decompress the spinal cord and is therefore excluded in lots of literature. Fenestration means to make a "window" in the affected disc UNDER the spinal canal and remove disc through a lateral or ventral incision (TL vs C-spine). This is also performed in adjacent discs in most cases.
July 2022...ACVIM consensus statement on diagnosis and management of acute canine thoracolumbar intervertebral disc exclusion (doi/epdf/10.1111/jvim.16480). A few key points are listed below and I will have more to share with you in future weeks.
Outcome of dogs managed medically or surgically, based on severity of presenting signs
Pain only. 80% of dogs had positive outcomes with medical management. 98.5% of dogs had positive outcome with surgical management.
Non-ambulatory paraparesis. 81% had positive outcomes with medical management however the level of recovery was less complete with medical management. 93% had positive outcomes with surgical management.
Paraplegia, deep pain intact. 60% of dogs had positive outcomes with medical management however this was prolonged and less complete compared to surgical management. 93% of dogs had positive outcomes with surgical management.
Paraplegia, deep pain absent. 21% of dogs had a positive outcome. 61% of dogs had a positive outcome.
The loss of deep pain causes the biggest shift in predictive statistics for surgical intervention. If you have any question about checking deep pain, please ask!
Medical management key points
Strict rest of 4 weeks is recommended based on low-level evidence to allow for healing of the annulus fibrosus. Strict rest is recommended by all, the 4 weeks part has low-level evidential support in the literature.
Corticosteroids are NOT recommended in acute intervertebral disc herniation and their use did not demonstrate superior outcomes in many studies. The exception is management of chronic signs in which corticosteroid use may show some benefit. (Not addressed in this article.)
NSAID use is recommended for at least 5-7 days, assuming no specific contraindication exists.
There is low-level evidential support for acupuncture or rehabilitation for dogs.
Surgical management key points
Much of the information provided is useful if you perform the surgery. If you do, please seek out the article as I won't be presenting those points here.
The timing of surgical decompression is hotly contested amongst neurologists (and surgeons performing neurosurgery). Conventional wisdom suggests early decompression leads to better long-term outcomes, and faster. This has not been consistently shown in the literature therefore the consensus statement elected to skirt the issue and not provide a "optimal window of time" recommendation. My thoughts (I was not on the consensus team, please note) is that if your client is able to seek surgical management please do so as quickly as possible.
That's it for this week. This is supposed to be a "TidBit" so I don't want to overwhelm you and discourage you from reading. If you perform these surgeries, or refer frequently, please consider reading the consensus statement. If you have any questions about what I've covered so far, or IVDH in general, please reach out! I will cover more from this statement paper in future TidBit Tuesdays!
Have a great week, stay warm, and enjoy these glorious sunny days of fall!
Large Breed Dogs and Disc Herniation
A little background...
Dogs greater than 10 kg experience type 2 disc herniation more frequently than type 1 disc herniation. (Refresher: Type 1 = acute extrusion of the center of the disc; Type 2 = bulge of outer ring of the disc into the spinal canal.) An estimated 10-30% of the time large breed dogs have type 1, depending on the study.
How is a type 1 disc herniation different for a large breed dog?
The answer is rather obvious, but glossed over frequently. They are bigger! That means nursing care is harder, surgery takes longer and is more extensive, and as a result there can be a greater expense for some of our larger dogs.
Does the prognosis change for a medium to large breed dog?
Yes. Dr. Woelfel from NCSU recently published data from a cohort of dogs > 10 kg that had both acute disc herniation and extensive spinal cord hemorrhage.
(Spinal cord hemorrhage occurs infrequently for large and small breed dogs and was shown in a few studies to have a minimal effect on prognosis as a stand alone feature. Meaning, the prognosis was still mostly based on the presence or absence of deep pain and didn't depend on spinal cord hemorrhage identified on advanced imaging.)
Okay, back to big dogs with disc herniation and spinal cord hemorrhage. The NCSU study reported a worse prognosis, and a higher complication rate, compared to overall data for small breed and chondrodystrophic dogs.
The details in summary:
No deep pain before surgery, recovery about 38% (general population: 50%)
Deep pain present before surgery, recovery rate about 77% (general population:90-95%)
Complication rate was about 24% (general population: 10-15%)
Post Operative Complications Noted in the Referenced Study
Decubital ulcers
Pneumonia
Self-mutilation
Fever of unknown origin
MDR UTI
Sudden death
Progressive myelomalacia
What is the take home message?
When talking with an owner of a medium to large breed dog with acute onset paraplegia, I suggest emphasizing the need for intense at-home nursing care, possible complications (along with the higher incidence) and a realistic prognosis if the dog is diagnosed with a disc herniation on advanced imaging. Remember that other differential diagnoses can cause acute onset paraplegia! Please do not interpret this paragraph as a call for euthanasia for large breed dogs with acute paraplegia. A 38% recovery rate is not zero! But a honest, open, vet-to-client discussion is the best way to achieve an informed decision for the client.
Not sure if you are interpreting the neurologic examination appropriately? Not sure if you are doing the neurologic examination properly? Please reach out! I am happy to work with you to help guide your clients in a compassionate and informed way.
Happy Easter to those that celebrated last weekend. We welcomed spring with big smiles around my house this weekend!
Reference: Woelfel, CW, Robertson, JB, Mariani, CL, Muñana, KR, Early, PJ, Olby, NJ. Outcomes and prognostic indicators in 59 paraplegic medium to large breed dogs with extensive epidural hemorrhage secondary to thoracolumbar disc extrusion. Veterinary Surgery. 2021; 50: 527– 536. https://doi.org/10.1111/vsu.13592
Prognostic Indicators for Acute Myelopathy
Acute Paraplegia: When to ship for surgery, treat medically or consider euthanasia
It happens to all of us (perhaps to me, more than you). Monday morning, 9 am, we are presented with a dachshund (Shih Tzu, Corgi...pick your top chondrodystrophic breed) after the dog became acutely non-ambulatory over night.
You perform a neurologic examination (self high-five!) and determine that the dog has a T3-L3 myelopathy with spinal pain at the TL junction.
What do you do next?
To be clear, a T3-L3 myelopathy does NOT equal a type I disc herniation. It means the dog may have a type I disc herniation or it could have a fibrocartilaginous embolic myelopathy (FCEM), acute non-compressive nucleus pulposus extrusion (ANNPE) or in rare cases meningomyelitis. (Yes, even dachshunds can get meningomyelitis!)
If we play the odds, that chondrodystrophic dog likely has a disc herniation. What, if any, prognostic indicators can you provide to the client?
Thankfully, an article out of Frontiers in Veterinary Science entitled "Prognostic Factors in Canine Acute Intervertebral Disc Disease" was published in November 2020 for just this purpose! (1) Here are some key points from the article. (The entire article is available as an open access article if you wish to read it in it's entirety. I highly recommend doing so if you are in the habit of seeing paraplegic dogs.)
Prognostic Indicator Key Points:
Recovery following medical management (only) for dogs with paraplegia (loss of all voluntary motor) and loss of deep pain perception (DPP) is about 22.4%.
Recovery following medical management (only) for dogs with paraplegia and intact DPP is 56%.
Recovery following surgical management for dogs with paraplegia and loss of DPP is about 61%.
25% recovered at 2 weeks
42% recovered by 4-6 weeks
53% recovered by 12 weeks
Recovery following surgical management for dogs with paraplegia and intact DPP is about 93%.
*** Did you catch that?? DPP is a prognostic indicator! Dogs without DPP do worse long-term compared to dogs with intact DPP. They are also have a 10x higher likelihood of developing progressive myelomalacia which is a fatal secondary outcome from acute spinal cord injury.
What exactly does "recovery" mean? It means walking without support but it DOESN'T mean walking normally or complete continence. Dogs may (and often do) have fecal or urinary incontinence consistently or occasionally following severe spinal cord injury.
Other Key Points:
Spinal shock can be more commonly associated with long-term fecal incontinence but does not seem to affect the ability to recover ambulation.
Age, breed and weight are not associated with prognosis...mostly. Some studies have found heavier dogs have a worse prognosis, other's haven't. My take - bigger dogs are harder to care for but that doesn't mean they cannot recover.
Reduced pelvic limb reflexes due to a L4-S3 lesion (not associated with spinal shock) has a higher likelihood of incontinence long-term.
When do you send a dog for surgery?
1) if the dog is non-ambulatory or paraplegic and the clients have a desire and financial ability to pursue surgery. Surgery with imaging costs $2000-5000 USD, depending on the specialty referral center.
2) Rapidly progressive signs (E.g.: dog was walking at 8 am, and is paraplegic at 10 am, with loss of deep pain by noon) and clients wish to pursue surgical intervention if indicated after imaging.
My plea...
Please don't send clients several hours to a specialist for surgery only to discover that the cost is prohibitively expensive. It is heart breaking for everyone and unnecessarily stressful for the dog. Call me and I'll happily talk with you about consult/medical management choices or sadly advocate humane euthanasia for the dog, if it is the best option.
Stay Safe, Keep Keeping On and Have A Good Week!
(1) Olby Natasha J., da Costa Ronaldo C., Levine Jon M., Stein Veronika M. Prognostic Factors in Canine Acute Intervertebral Disc Disease; Frontiers in Veterinary Science. 2020:7 p 913.
The Five Types of Disc Herniation
The Five Types of Disc Herniation (that we know of!)
Dystrophic calcification secondary to chondroid degeneration of nucleus pulposus (NP), called a Hanson Type I. This causes mechanical stress on the outer annulus fibrosus (AF), leading to rupture of individual collagenous strands of AF and eventually full failure.
Fibrous degeneration occurs when fibers of disc split leading to accumulation of tissue fluid and plasma between them. Over time the mechanical pressure exerted by NP causes thickening of the AF dorsally, causing protrusion. (Hanson Type II).
ANNPE (Acute noncompressive nucleus pulposus extrusion) - this is normal NP that is exploded into the canal, usually during activity. Also called a traumatic disc herniation.
AHNPE (Acute hydrated nucleus pulposus extrusion) – An apparently normally hydrated NP that is compressive and often located ventral to the cord, often in the neck.
Significantly more neuro deficits and less signs of cervical pain with AHNPE compared to other causes of cervical myelopathy.
FCE (Fibrocartilaginous embolism): a piece of NP that becomes dislodged and finds its way into the vasculature surrounding the spinal cord. This can be into venous or arterial blood vessels. The end result is an acute shift in blood flow at the level of the spinal cord.
Match the clinical sign with the type of disc herniation
A. Chronic, progressive ataxia progressing to paresis
B. Acute, non-progressive unilateral weakness affecting one leg, or one side (hemiparesis)
C. Acute, progressive, painful ataxia progressing to paresis in a chondrodystrophic dog
D. Acute non-progressive ataxia and paresis affecting both sides of the body (paraparesis or tetraparesis)
E. Acute, rapidly progressive tetraparesis and ataxia of all four limbs with minimal cervical pain
If you answered...
Type I: C
Type II: A
ANNPE: D
AHNPE: E
FCE: B
you are correct!
Based on the clinical picture, it can be very difficult to distinguish Type I from ANNPE, and AHNPE. Typically, type I is painful (but not always), and the other two are minimally to non-painful.
Which of these require surgery?
Any disc herniation that results in compression of the spinal cord with associated clinical signs could be considered for surgical correction. This statement would then suggest that Type I, Type II and AHNPE could be surgically corrected. Therefore, any patient with signs of a progressive or painful myelopathy should be evaluated for diagnostic imaging (typically MRI) for possible surgical intervention whenever possible.
Bonus question:
Can you name two diseases that are commonly diagnosed instead of a type I or type II disc herniation? Scroll to the bottom for the answer!
Change is coming! Starting in September I will have new fees, and new availability. I am happy to accommodate outside of these hours whenever possible so please reach out if you cannot find a suitable time using the online scheduler. ( https://barnesveterinaryservices.com/ )
New Hours (Starting September 8th)
Monday 11a-1p, 4-5p
Tuesday 3-4p
Wednesday 11a-1p, 2-4p
Thursday 2-4p
Friday 12-1p
Saturday 9-11a
Bonus Question Answer
Meningoencephalomyelitis (a.k.a meningitis), and neoplasia. Keep these two on your differential diagnoses list when you suspect a disc herniation!!
The Genetics of Disc Herniation
What is the deal with chondrodystrophy, anyway?
Chondrodystrophic dogs are born to have short stature, and abnormal aging of the intervertebral discs. It's what makes a Dachshund or French Bulldog look like, well, a Dachshund or French Bulldog! I'm sure it comes as no surprise that there is a genetic reason why they look this way. But, did you know that someone has sorted out the genetic mutation that has been linked to chondrodystrophy and disc herniations?
What is the genetic mutation and what does it mean?
Several studies in 2019 (and earlier) looked at copies of 12-FGF4RG and 18-FGF4RG status in chondrodystrophic dogs and found that if a dog carried at least 1 copy of the 12-FGF4RG gene they were significantly smaller, younger and more likely to have radiographically calcified discs than those without. Furthermore, 12-FGF4RG was the only factor identified in multivariate logistic regression models that contributed to needing disc herniation surgery in mixed breed dogs. Mixed breed dogs? (You ask.) Yes, Dachshunds and French bulldogs, specifically, have such a high rate of carrying 1 or 2 copies of the 12-FGF4RG gene that it's impossible to say with the relative risk of disease is for these breeds with the mutation. In other words, if every Dachshund has the mutation is it actually related to disc herniation? Not sure yet. One study found that non-Dachshund and French Bulldogs had between a 5.1-15.1 fold increase of disc herniation if they had at least 1 copy of this gene.
What do I do with this information?
If you have a neutered animal, nothing. It might predict the risk of disc herniation in that animal but that animal is already born, and presumably loved, so this information is not actionable. If you have a client considering breeding you may be faced with the results of this genetic information and asked the question above. My opinion? There are specific breed risks so either read the published data on risk for the specific breed in question, or reach out to me and I'll gladly pass along the information. It's in a handy table, but not my data so I don't feel comfortable including it in the TidBit Tuesday mailer. If possible, breeders should try to breed dogs with zero or 1 copy to dogs with 1 or zero copies of the mutation to reduce it's presence in the breed. *This doesn't apply to Dachshunds or French Bulldogs for the above mentioned reasons!
Keep those chondrodystrophic dogs fit, healthy, and leading low impact lifestyles! It won't eliminate the risk of a disc herniation but it may make recovery easier.
Batcher K, Dickinson P, et al. Phenotypic Effects of FGF4 Retrogenes on IVDD in Dogs. Genes (Basel) 2019; 10(6): 435.
Do you have a case you'd like to discuss with me? Feel free to email, text, or call me! I'm still trying to see mostly video consults whenever possible but I'm gradually increasing the live consults performed. Either way, I look forward to (continuing) to work with you!