Outlook for a 4 year old with CM?

Hi everyone,

This is my first time posting here, but reading threads has been really helpful for understanding CM/SM. Our Winnie just turned 4 and was diagnosed with CM (via MRI) in December 2014 after an episode of ataxia that lasted a couple of days. We put her on a short course of Gabapentin, but then she recovered with seemingly no pain so I saved the rest of the pills for a "rainy day". The neurologist thought that maybe something (e.g. weather change) tweaked her intracranial pressure, leading to the acute episode. About a month ago she had a couple of bad episodes of fly-catching and seemed to be bothered/in pain during them. After that she started doing the fly-catching intermittently almost every day, and while in the midst of it sometimes showed behaviors indicating pain (biting at paws, rubbing up against the sofa). I took her back to the neurologist last week and started her back on Gabapentin which is completely eliminating the fly-catching and any signs of pain. We also had her re-scanned since the neurologist was concerned that the worsening of symptoms could mean that she has developed SM and may be a candidate for surgery.

According to the results, her MRI is stable (CM with resulting hydrocephalus but no SM) and the neurologist (who has lots of experience with CM/SM) feels that Winnie's case is pretty mild in the grand scheme of things. She believes that Winnie's case can be managed by just keeping up with the Gabapentin and that the stable MRI is a very good sign.

I guess what I am wondering is how things have turned out for others' dogs when they've gotten a similar prognosis. I know CM/SM can be unpredictable, but I am just curious to hear others' experiences (whether things stayed the same or took a turn for the worse down the line). Thank you for reading my long-winded post!

I'm sorry to hear that Winnie has CM, but no sign of a syrinx so far is good news. Having said that, some experts feel that CM alone can be trickier to control than SM, because inter-cranial pressure can be so painful. Both my Cavaliers with SM - who were put to sleep last year but that had nothing directly to do with their CM/SM - had small syrinxes that never seem to have done any harm. Oliver was diagnosed at the age of 6, but with hindsight and more knowledge he had symptoms from the time I had him at a year old. His major problem was severely dilated ventricles and resultant pressure behind the eyes. He was very light phobic and had bad headaches that gabapentin didn't touch. Completely fortuitously, when taking part in a Royal Veterinary College blind trial of alternative painkillers for CM/SM, he was put on a different drug that worked brilliantly to stop his headaches. This was a human drug called Topirimate, used to reduce intercranial pressure in epilepsy. Unfortunately it can produce quite serious side-effects in some dogs, so doesn't seem to be generally used - we were just lucky that it suited Oliver. It controlled his headaches for 7 years, though I always had to be careful of his light phobia - he wore a sunhat and I tried to keep him out of strong light; even sitting in the shade looking out at bright sunlight would start a headache.

Oliver lived a full life until he got old and almost completely deaf. In the last three years of his life he had progressive hind leg paralysis, but this didn't seem to have anything to do with his SM; it seemed to be degenerative myelopathy (the disease that affects many German Shepherds). Indirectly, his CM/SM did affect my decision to put him to sleep at the age of 13 - quite suddenly he started having slightly increased symptoms such as occasional headaches in spite of his medication, and pain in his front leg, and as he was already on the maximum dose of gabapentin, the thought of trying to manage that on top of all his other problems did contribute to my decision.

But with medication, Oliver lived a normal life: he did competition obedience, he was a Pets as Therapy visitor, I showed him with moderate success, we went on holiday together, staying in cottages and camping in a tent in all parts of Britain, he was completely unflappable and rather independent, loved long walks and people, and was a brilliant ambassador for the breed. That's him in my avatar.

It is important with gabapentin that you keep using it regularly. It is not a pain killer, to be given only when Winnie seems uncomfortable. It is a pain suppressant specifically for neurological pain (it's useless for other types of pain) and acts as a blanket preventing pain rising into consciousness, so you need to keep the coverage going (most dogs need to have it three times a day to maintain the coverage). Having said that, there are times when you will need to increase the dose temporarily. One of these is rapid changes in air pressure; it's worth looking at a weather website or getting an app; once you get the connection between Winnie's discomfort and air pressure change, you can foresee when she is likely to need extra gabapentin or a morning dose of Metacam for a day or two. Some Cavaliers react to high pressure; Oliver didn't like the pressure bumping along the bottom for several days. The average pressure is 1010 millibars, so anything in the 1020s or 990s can cause problems. Not all Cavaliers have this sensitivity, but it seems quite common.

Hope some of this helps. Treatment for CM/SM is improving as different drugs are tried; it needs managing and can sometimes be a bumpy ride, but with luck Winnie will be able to lead a pretty normal and happy life. But some dogs (and owners) are not so lucky and the pain becomes uncontrollable. I do hope Winnie won't be one of those. Keep us informed of how she's doing - we have a lot of expertise on this forum, and a lot of caring to support you in whatever Winnie's future brings.

Kate and Ruby (7-year-old Blenheim rescue)

PS Given that almost all the drugs for CM/SM are for humans (I take gabapentin myself!), you may be amused by a remark the leading researcher Clare Rusbridge made at a health seminar I went to: 'We don't give any drugs to dogs that haven't been thoroughly tested on humans'!

Thanks for the info Kate! It makes sense that Gabapentin suppresses pain rather than relieves it once it's there. I've set an alarm on my phone to make sure Winnie gets her pills on time. She is actually doing great on just 2 per day (1 every 12 hours), but I won't hesitate to go up to 3 if she shows breakthrough symptoms/pain. I will keep an eye on the barometric pressure to see if there is a connection for her.

No one knows what the future holds for any dog with CM/SM, but it's nice to hear that some dogs can live a long life with it. We have decided that we will do what is needed for Winnie to live a happy, comfortable life (even surgery if that ends up being warranted down the line) and just enjoy her for as long as we have her. Fingers crossed it's a long time!