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25% of cavaliers with SM symptoms have CM only, not SM

Karlin

Karlin

Administrator
Staff member
That's according to a research sample of clinically affected, scanned cavaliers in the new research paper out from Clare Rusbridge et al. This is the same one Rod notes in an earlier thread about 76% of these dogs also had further syrinxes lower than the C5 vertebrae (and thus dogs with syrinxes are likely to be worse than a mini scan will show).

Abstract below, but this excerpt from the paper interested me as it suggests a hitherto unexpectedly large number of dogs with clinical signs of SM (all dogs in the study had clinical signs)-- one in four!!! -- have CM only -- which suggests people with such dogs really need to be treating it AS WITH SM, not attributing the problem to some other likely cause (something vets also need to recognise):

The median age of the dogs included in the study was 5 years (1.2–10.8 years). CM was present in all patients. None of the dogs showed compressive craniocervical pathology other than CM. There was no evidence of SM on MRI in 12/49 (25%) dogs. In all dogs with MRI evidence of SM (37/49; 75%), SM was present within the C1–C4 region (Figs. 2 and 3). Of those dogs with SM within C1– C4 region, 76% (28/37) also had SM within the C5–T1 and/ or T2–L2 regions, but only 49% (18/37) had SM within the L3–L7 region.
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Abstract

Chiari-like malformation (CM) and syringomyelia (SM) is an important disease complex in the Cavalier King Charles Spaniel (CKCS) but data about the anatomical distribution of SM along the spinal cord are lacking in veterinary medicine. The objective of this study was to define the anatomic distribution of SM in CKCS clinically affected by CM/SM. Magnetic resonance imaging (MRI) of the brain and the entire spinal cord of 49 dogs was performed and different morphological parameters compared.

Syrinx formation was present in the C1–C4 region and in other parts of the spinal cord. The maximal dorsoventral syrinx size can occur in any region of the spinal cord and the total syrinx size was positively correlated with age. Seventy-six per cent of CKCS with a cranial cervical syrinx also have a syrinx affect- ing more caudal spinal cord regions. MRI restricted to the cervical region may underestimate the extent of SM and the severity of the disease process in the majority of dogs.
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Karlin said:
25% of cavaliers with SM symptoms have CM only, not SM

That's according to a research sample of clinically affected, scanned cavaliers in the new research paper out from Clare Rusbridge et al. This is the same one Rod notes in an earlier thread about 76% of these dogs also had further syrinxes lower than the C5 vertebrae (and thus dogs with syrinxes are likely to be worse than a mini scan will show).

Abstract below, but this excerpt from the paper interested me as it suggests a hitherto unexpectedly large number of dogs with clinical signs of SM (all dogs in the study had clinical signs)-- one in four!!! -- have CM only -- which suggests people with such dogs really need to be treating it AS WITH SM, not attributing the problem to some other likely cause (something vets also need to recognise):
Click to expand...

The researchers in that article go on to explain about the pain sensations experienced by the dogs having only CM:

Dogs with CM without SM can experience discomfort and pain possibly due to a direct compression of the medulla oblongata, which is involved in modulation of pain and projects to trigeminal nuclei and spinal cord dorsal horn (Rusbridge and Jeffery, 2006; Taylor and Larkins, 2002).
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One other item in the article, which I found to be interesting, is this:

... measurements of the syrinx in T2-weighted images may result in an overestimation of the syrinx size as they include the hyperintense signal associated with interstitial oedema. In the majority of cases in our study, the syrinx borders were not well demarcated on T2-weighted MR images. Syrinx outlines were however distinctly visible in T1-weighted images. In view of these findings and the reported literature, T1-weighted images were used for all measurements in our study.
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Can someone explain in simple terms some things.

1) I have read that as much as 95% of ckcs have CM (correct me but this seems on the higher side and I am not sure where I saw that sorry). With these results along with people on forum and others I have talked to have said that their cavaliers have symptoms pain with CM alone, do we know why some have more "severe" or symptamatic?

2) karlin, you bring up a good point about them both being treated the same meaning with medication etc. It seems like SM/CM either one can be painful or not (depending). You could argue that a CM (no SM) with symptoms compared to an asymptomatic SM cavalier would bring up a whole other can of worms. Just because they do not have SM, doesn't mean they are better off especially if they have pain.

3) in other breeds, someone mentioned that they can have SM without CM. Is that pretty much just other breeds? Maybe the only time you would see in a cavalier is if it was caused by an accident?

4) do we know why some develop symptoms and others not? Especially since there is a larger % of cavaliers with CM?

I guess that's it for now.. sorry for the questions but seems with research you find information that brings up other questions.




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anniemac said:
Can someone explain in simple terms some things.

1) I have read that as much as 95% of ckcs have CM (correct me but this seems on the higher side and I am not sure where I saw that sorry). With these results along with people on forum and others I have talked to have said that their cavaliers have symptoms pain with CM alone, do we know why some have more "severe" or symptamatic?

2) karlin, you bring up a good point about them both being treated the same meaning with medication etc. It seems like SM/CM either one can be painful or not (depending). You could argue that a CM (no SM) with symptoms compared to an asymptomatic SM cavalier would bring up a whole other can of worms. Just because they do not have SM, doesn't mean they are better off especially if they have pain.

3) in other breeds, someone mentioned that they can have SM without CM. Is that pretty much just other breeds? Maybe the only time you would see in a cavalier is if it was caused by an accident?

4) do we know why some develop symptoms and others not? Especially since there is a larger % of cavaliers with CM?

I guess that's it for now.. sorry for the questions but seems with research you find information that brings up other questions.
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Enough, already! You're making my head hurt!

Yes, some researchers have estimated that as many as 95% of cavaliers may have Chiari-like malformation (CM). That is based upon statistics among CKCSs examined during the researchers' studies. If that percentage is close to accurate, then it may also be said that CM is "normal" for the breed, meaning that so many have it, that not to have it is abnormal.

It is like the Dalmatian. 100% of Dalmatians registered with the American Kennel Club (AKC) have a malformed version of the SLC2A9 gene, which causes excessively high levels of uric acid, and in up to a third of all males, also creates painful urate stones which can cause blockages and which may require repeated surgeries to remove. In the AKC version of the Dalamatian, the malformed SLC2A9 gene is "normal".

It's like in an insane asylum, crazy is normal.

Back to the article being discussed: As the researchers have explained, "Dogs with CM without SM can experience discomfort and pain possibly due to a direct compression of the medulla oblongata, which is involved in modulation of pain and projects to trigeminal nuclei and spinal cord dorsal horn."

I don't think they yet know why some dogs have pain from CM and others do not. Perhaps it is the severity of the CM, combined with the level of the threshold of pain in the particular dog. It is difficult to objectively measure the level of pain in a dog.

But the fact that (a) CM alone can cause severe pain, coupled with the other fact that (b) a large majority of cavaliers -- maybe not 95% but a high number nonetheless -- have CM, can amount to this scary proposition: (c) That CM is normal in the breed, and pain is, perhaps, normal for CM, so therefore, pain is normal in the breed.

As it is with the Dalamatian: high levels of uric acid are normal, causing painful stones in a third of the males. So it may be with the cavalier: nearly all have CM, which alone can cause severe pain. We just don't yet know what the percentage of cavaliers with painful CM is yet.

Yes, in other breeds, including the Griffon, syringomyelia (SM) may appear without CM. In the cavalier, absent a trauma or other environmental influences, SM exists only if CM exists.

A corrollary to your question about CM is: Why do some cavaliers with SM have symptoms and others do not? That has been a topic of studies. In a 2007 report ( http://www.cavalierhealth.org/syringomyelia.htm#Syringomyelia_in_cavalier ), the researchers wrote: "Maximum syrinx width was the strongest predictor of pain, scratching behaviour and scoliosis in dogs with syringomyelia. Both pain and syrinx size were positively correlated with syrinxes located in the dorsal half of the spinal cord."

Also, in a 2010 study ( http://www.cavalierhealth.org/syringomyelia.htm#Transcranial_Magnetic_Motor_Evoked_Potentials ) the researchers reported: "A significant linear correlation was observed between the severity of neurologic dysfunction and size of the syrinx, with a larger syrinx being associated with more severe neurologic signs."

Since SM is progressive, it may be that for cavaliers with SM but no pain, it is just a matter of time. Much like dying from congestive heart failure due to MVD is just a matter of time for many cavaliers with incipient murmurs.
 
Rod, I'm going to FL tomorrow. Don't you live in Tallahassee? Why don't I stop by and I can ask you questions for a couple hours? I bet that sounds fun :)

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Thank you for posting this Karlin - it's very scary, particularly as breeders are making decisions based on the absence of presence of syrinxes...


What a truly awful thought that pain might be the NORMAL condition for the Cavalier :(:(:(:(


Annie, you raise good questions and we are lucky to have some very informed members to answer them (y)
 
Karlin said:
it suggests a hitherto unexpectedly large number of dogs with clinical signs of SM (all dogs in the study had clinical signs)-- one in four!!! -- have CM only -- which suggests people with such dogs really need to be treating it AS WITH SM, not attributing the problem to some other likely cause (something vets also need to recognise):
Click to expand...


Firstly this incidence is truly shocking :(:(:( [although relates to my personal experience - I thought perhaps we had just been unlucky]



from http://sm.cavaliertalk.com/

Typical symptoms may include only ONE, or SEVERAL, of these signs:

  • excessive scratching, especially at ears, head, face, neck, shoulders (only some SM dogs scratch!)
  • 'air scratching' (the hind leg makes no body contact, typically when walking the dog)
  • scoliosis (especially in young dogs), where the dog's neck and spine bend into a 'C'
  • weakness in the legs
  • pain, especially around the head, spine and/or legs
  • sudden yelping for no reason
  • flipping around to bite at the hindquarters
CM/SM is often misdiagnosed by vets as:

  • allergies
  • ear problems
  • spinal/disk problems

CM - treating it AS WITH SM

treatment options here

http://sm.cavaliertalk.com/treating/treatingsm.html
 
Nicki said:
What a truly awful thought that pain might be the NORMAL condition for the Cavalier :(:(:(:(
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I feel totally depressed at that thought, because I believe it may well soon be the truth.

I really struggle with the question as to whether the incidence of both CM and SM is rapidly getting worse, or whether awareness of the condition has made owners more aware of 'quirky' behaviour that would not have been recognised as pain symptoms in the past.

Although I know I have owned cavaliers in the past that on hindsight showed mild symptoms, I do not believe that the extent of suffering in young dogs that we are seeing now would have gone unnoticed. I worry we are at the start of an explosion of dogs showing up with pain caused by CM and/or SM.

I have a scanned dog staying with me who has CM, no SM, but his symptoms are obvious and he has been prescribed painkilling medication.
Grooming him leaves him scratching uncontrollably however gentle I try to be.
 
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Dougall has cm and Molly has sm. Molly was suffering badly and in some ways Dougall was suffering more. They are both on the same pain medication. Dougall has a problem with his back and head. According to his scan his Dorsal Horn has been damaged.

I have read in previous posts, "Cavaliers are whimps they have a low pain threshold".
I believe the opposite is true. Maybe they are in pain and simple things like grooming, injections etc. is the step over the pain threshold :(
 
Tania said:
Dougall has cm and Molly has sm. Molly was suffering badly and in some ways Dougall was suffering more. They are both on the same pain medication. Dougall has a problem with his back and head. According to his scan his Dorsal Horn has been damaged.

I have read in previous posts, "Cavaliers are whimps they have a low pain threshold".
I believe the opposite is true. Maybe they are in pain and simple things like grooming, injections etc. is the step over the pain threshold :(
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Tania, I was hoping you would respond because I was thinking of cute dougall.

To respond to cavaliers being wimps, I would like to quote sandy Smith from her book for the love of Ollie.

"Good luck, my sweet Cavaliers. We understand now that you are not so "wimpy" after all. You are, in fact, one of the most courageous, Stoic and loyal little companions we have ever had."

If you ever read what a person with CM says, then no one would think Cavaliers are wimps at all. I wish I had an ounce as much strength as Ella.

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As I have mentioned before, Oliver has more problems from his CM than from his small and narrow syrinx. Clare Rusbridge has a photo on her website of severely dilated ventricles, and that's exactly what Oliver's last scan, 2 years ago, looked like. If the ventricles are pushing the brain outwards, it's got to go somewhere and in Oliver's case it presses on the skull behind his eyes, causing him to be light phobic (to snow as well as strong sunlight, as I discovered this winter) and have headaches. I take precautions to keep him out of the sun, and 3x100mg gabapentin seems to be controlling the headaches well. He's been slightly light phobic all his life, but it seems to be quite a rare symptom so wasn't picked up as a possible sign of CM.

His only other symptom is lack of nerve response in his right front leg, which his neurologist feels could also be due to the dilated ventricles interfering with the route of the nerves from the brain rather than damage in the leg itself; the only result of this is that Oliver feels more comfortable lying down for any length of time rather than sitting - sitting puts a lot of weight on the front legs. It certainly doesn't stop him running around!

He has only had two mini-scans, but from his comparative lack of symptoms there seems to be no evidence of any syrinxes further down. So long may his one syrinx stay narrow! He's 10 this year.

Kate, Oliver and Aled
 
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