Explaining SM

I’ve been reading up on various sticky’s on the site regarding SM in Cavaliers from reading up I felt the possibility of a Cavalier developing it is quite high particularly for Rescue Dogs ie ex breeding dogs etc who won't have been screened. Is that right?

I’ve been wondering what the treatment options are, I have read about an operation are there other ways of controlling it by medication?
If the dog is Insured do you find Insurance companies cover the cost of the MIR scan etc?

I have read a few of the links and stickys but found the research etc.. a bit difficult to process but it could be because it’s all new to me wondered if anyone can simplify it a bit.

Actually, some of the researchers feel dogs from established show breeders may well be at a somewhat higher risk because of 'popular sire syndrome' -- in the past 2-3 decades in all breeds, there's been a trend to excessively use the same small groups of winning sires thus vastly reducing gene pool diversity and concentrating the same limited group of family genes on the father's side -- as the years pass, as more and more dogs of these matings themselves are used for breeding, the similar backgrounds again become even more concentrated. Researchers have noted:

A salient fact is that 93% of top stud dogs in the UK are closely related to 1 or more dogs with SM and the pedigrees of these dogs are similar to Champions worldwide.

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By contrast dogs from mills or other casual backgrounds may have quite diluted bloodlines.

That said, mill and BYB dogs are overall at a much higher risk of many conditions far more likely to compromise or take their lives than SM, such as MVD. And all evidence is that ALL lines worldwide carry genes for SM and mill and byb dogs generally are not too many generations removed from those 'champion ancestors' they advertise on their sites. So realistically probably it matters little with regard to SM generally.... BUT there is research that shows that breeding A grade dogs reduces the risk of SM-affected offspring, so people concerned about SM should think seriously about going to breeders who have MRI graded their dogs and ideally, know the MRI grades of some related dogs as evidence so far shows clear dogs (no syrinxes) tend to be closely related to other clear dogs.

There are medications to control the pain of SM and perhaps slow progression (the latter is not proven) but no medication corrects the problem and there is no actual cure. Surgery can stop progression though and reverse some damage but most damage is permanent. That is why surgery is best done early if it is being considered.

Probably most cavaliers have the skull malformation that can lead to SM (syrinxes forming). The malformation alone seems to cause similar symptoms to SM in some dogs (as it does in humans). In research samples, between about 35-70% of dogs actually had SM (syrinxes) though most were not symptomatic. As the condition develops slowly, researchers feel many dogs simply adapt to the pain as humans often do, and simply live with it, with no outward expression of pain or minimal expression. It is one reason why it is very hard to know exactly what the dogs experience but if you know anyone who has chronic neurological pain, you'll know they rarely outwardly show that pain and I would guess dogs are often the same, especially as they cannot tell us they hurt.

My dog that has SM has his pain managed with a couple of drugs but I will likely have him reexamined this summer by Clare Rusbridge and consider the option of surgery, depending on his prognosis.

Thanks Karlin, that makes sense about the diluted bloodpool and breeding from A grade dogs.
How long of a life span on average do Cavs suffering from SM have?
Would a dog have to be put to sleep due to the pain from SM or is it always operable or managed.

Yes I have read up on MVD to, poor Cavs seem to get it all
I was under the impression MVD can be managed with meds, is that right?

Flutterbye said:

Thanks Karlin, that makes sense about the diluted bloodpool and breeding from A grade dogs.
How long of a life span on average do Cavs suffering from SM have?
Would a dog have to be put to sleep due to the pain from SM or is it always operable or managed.

Yes I have read up on MVD to, poor Cavs seem to get it all
I was under the impression MVD can be managed with meds, is that right?

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(1) variable and unpredictable.

(2) unfortunately, yes.

How long of a life span on average do Cavs suffering from SM have?
Would a dog have to be put to sleep due to the pain from SM or is it always operable or managed.

Yes I have read up on MVD to, poor Cavs seem to get it all
I was under the impression MVD can be managed with meds, is that right?

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1) Totally variable and unpredictable. Clearly MOST dogs with SM lead normal lives as research samples show huge numbers have it while remaining asymptomatic. Going by rescue samples probably at least half of all cavaliers have syrinxes by the time they are five or so; but more MRIs are needed and more studies to get a better handle on level of affectedness. Generally dogs showing symptoms before age 2 are far more severely affected though showing them before 4 is considered a more rapid onset form as well. Younger dogs with symptoms -- under a year -- are generally pretty severe cases that need the surgery for any chance of a life.

2) Also variable. My SM dog is managed on painkillers and is approaching age 5, He was symptomatic after 2.5 years but was MRId with a syrinx at about 15 months. Some dogs have very mild symptoms all their lives, some have none, some progress very rapidly.

3) Variable as well. About half of cavaliers have a murmur by age 5. Early onset murmurs (before age 5) tend to be worse. The medical treatment is quite well known for MVD and some dogs never even need medication, some do eventually, some get small benefit; some get many extra years. Again, it depends on the dog and when treatment is given to various degrees.

Thanks for the information, it must be heartbreaking for all you owners who Cavs have been diagnosed, so much worry and stress.

I notice on some Rescue sites they mention if the Cav has a heart murmur I wondered if it is standard to have it diagnosed prior to rehoming?
I'm guessing pet insurance wouldn't cover it then as it's a pre standing condition?