Our precious cavaliers may encounter this devastating disease. Reputable breeders are working hard to minimize the odds of this in their bloodlines, but it is not an exact science. SM is a complex disease. There is so much we don’t know about it. We can have dogs who don’t exhibit symptoms produce it,. There are some who are diagnosed by MRI with it, who are asymptomatic (no symptoms), and others who do have it and exhibit symptoms.

Unfortunately we can not genetically test for it, so we have no way to predict which puppies may or may not get it. We do know it is polygenic. This means that it must be inherited from both sides, and it does seem to look like it can be passed hidden through many generations before popping up in the “perfect storm” in one puppy who exhibits the symptoms.

The Cavalier King Charles Club (CKCS) put together some information about SM that I wanted to share with you.

SM is a progressive neurological disease that varies in severity. Cavaliers unfortunately are affected by SM in larger numbers to any other breed. It is found in all colors, in all lines, and affects both sexes. Signs are usually noticed in dogs between 6 months and 3 years but it has been diagnosed in Cavaliers up to 10 years old. At present the condition can only be identified by MRI scan or by clinical signs. SM occurs when a Cavalier is born with not enough room in the space in the skull that contains the back of the brain. Damage is caused when fluid (CSF) surrounding the brain is forced through a smaller than normal opening, into the spinal cord. The most common symptom is scratching on, or in the air near, the shoulder when the dog is excited or walking on a lead. However this is not the only symptom and it is not always present. Some refer to SM as “neck scratcher’s disease” because scratching the neck is often a sign of the disease. 

The primary symptoms (usually at least one of these is present) are described as:

• Excessive Scratching especially while on the lead, and often ‘air scratching’ where the dog scratches in mid-air, leading to a ‘bunny hop’ gait as the dog tries to scratch the air with one leg and walk. Sometimes touching the dog’s ears brings on scratching.
• General Pain is often first noticed because a dog begins yelping or whining or whimpering for no reason. Pain episodes can disappear then return even after a year or more. In some dogs weather changes such as storms or a cold front seem to bring on episodes.
• Weakness in Limbs where some dogs may show a lack of coordination. They may limp slightly. Dogs can start to have difficulty getting on and off couches and beds. A paw or leg might go weak. Some dogs will lick at their paws or legs obsessively, often until raw.

The secondary symptoms are described as:

• Seeking Cool Areas or Restlessness where an affected dog will shift constantly rather than sleep comfortably.
• Head shaking, lip-licking. Dogs often will shake their heads and ears, yawn excessively (probably an attempt to clear pressure they feel in their heads), or lick at their lips excessively.
• Head rubbing. Some dogs start to rub their head from side to side on the floor as if their heads hurt, doing this excessively (NB: normal dogs will do this with pleasure, often before rolling on the floor). They sometimes ‘mush’ their face against the floor.
• Digging or pushing. Some dogs begin to dig obsessively at carpets or sofas. They may run along the length of a sofa pushing themselves against it. Again, this behavior is normal in many dogs; with SM dogs, the activity is frantic.
• Nerve damage, stiffness, seizures. This can affect a dog in many ways, from loss of feeling, hearing, or muscular movement. Some dogs have neurological problems with their eyes. Nerve damage seems to be progressive with this condition though some dogs have little or no visible damage and others have severe damage. Some dogs develop a stiffness in the neck, back and/or limbs. In severe cases the neck may bend to the right or left (‘neck scoliosis’), or the whole body may bend into a ‘C’ shape when the dog runs. The head may tilt permanently to one side or the other. The dog may have head tremors. Some dogs begin to have seizures, in some cases, several a day.

Understandably, such descriptions can be confusing – how much scratching is ‘excessive’, for example? Some people might turn to their vet with such questions, but many have found their vets were unfamiliar with syringomyelia. 

Medical management can help but typically does not resolve the clinical signs. Signs in mild cases may be controlled by non steroidal anti-inflammatory drugs (NSAIDs) e.g. Rimadyl. Although corticosteroids are effective in limiting the signs most dogs require continuous therapy and subsequently develop the concomitant side effects of immunosuppression, weight gait and skin changes but sometimes there is no alternative and the lowest possible dose should be used to control signs. Gabapentin can also be given in combination with NSAIDs. Side effects are minimal and for this reason Gabapentin is preferred over corticosteroids. Oral opioids are also an alternative for example pethidine tablets at 2-10mg/kg three to four times daily or methadone syrup at 0.1-0.5mg/kg three to four times daily. Acupuncture appears to help some dogs. If the dog has seizures, then these can be controlled with phenobarbitol and potassium bromide

“Introduction to Syringomyelia” by Dr Clare Rusbridge, BVMS DipECVN MRCVS
and “Syringomelia Symptoms” by Karlin Lillington