Syringomyelia (SM) is a very serious, progressive spinal disease which is becoming very widespread in Cavalier King Charles Spaniels (CKCS) of all bloodlines. It is a genetic intraspinal disorder due to congenital caudal occipital malformation syndrome or syringomyelia secondary to occipital hypoplasia (Arnold Chiari-like malformation in humans). This malformation changes the shape of the skull so that the brain is compressed, causing incomplete closure or development of the neural tube, and fluid build-up in the brain and spinal cord. Current research in the UK indicates that at least 50% of CKCS have some degree of occipital hypoplasia, although not all are so severely affected as to manifest SM.
[Note: There are other forms of syringomyelia in canines: (a) spinal dysraphism or spinal dysplasia, a genetic disorder in which puppies under the age of three months display a bunny hopping gait and wide-based stance and scoliosis; and (b) SM caused by trauma.]

Symptoms
The number of diagnosed cases in CKCS has increased dramatically in the last 5 years. SM cannot be detected in puppies, as symptoms usually are not evident before the age of six months or even years later. The progression of disease is variable among affected dogs.

The spinal cord damage results in symptoms of hypersensitivity, intense pain, and leg dysfunction. In early stages, there is sensitivity in the neck area, causing the affected puppy to have an uncontrolled urge to scratch at the neck and shoulders. This is followed by severe pain around head, neck, and shoulders, causing the pup to yelp or scream. As the disease destroys portions of the spinal cord, it becomes so painful that the dog may contort its neck and even sleep and eat only with its head held high. There may also be progressive weakness in the legs, and loss of bladder and bowel control. Some dogs deteriorate to the point of paralysis.

Diagnosis
The only accurate way to diagnose the disease is through magnetic resonance imaging (MRI). When examined by MRI, the SM appears as a pocket of fluid within the spinal cord. In severe cases, the syrinx is so wide that only a thin rim of spinal cord is visible.

Another disorder common to CKCS and with similar symptoms is primary secretory otitis media (PSOM), a highly viscous mucus plug which fills the middle ear and causes the tympanic membrane to bulge. Because the pain and other sensations in the head and neck areas of PSOM are so similar to symptoms of SM, this possibility should be ruled out before diagnosing SM.

Treatment
There are few treatment options for SM. Before the disease progresses to its severe form, use of cortisteroids or non-steroidal anti-inflammatory drugs may relieve the symptoms but not the deterioration. Anticonvulsants, such as gabapentin (Neurontin), have been successful in some severe cases, or oral opioids can be tried as alternatives. Methylsulfonyl-methane (MSM) is recommended by some veterinary neurologists as a dietary supplement.

Drugs which reduce the production of cerebrospinal fluid, including proton pump inhibitors such as omeprazole (Prilosec), and the diuretic, furosemide (Lasix), may be useful, but clinical data on their use and effectiveness is lacking. Carbonic anhydrase inhibitors, such as acetazolamide (Diamox) also serve to decrease the flow of cerebrospinal fluid, but the adverse side effects of abdominal pain, lethargy, and weakness limit long term use.

Surgery to allow the cerebrospinal fluid to flow normally may be necessary to reduce the pain and deterioration, and in some cases a shunt is installed. Although surgery often is successful, many dogs either have a recurrence of the disease or still show signs of pain and scratching.

Current Research
Ongoing research by Rusbridge and Knowler, in cooperation with CKCS clubs and breeders throughout the UK, North America and Europe, is aimed at collecting DNA from normal and affected dogs to search for the recessive genes involved. At Ohio State University, Abramson and colleagues are searching for a reliable, minimally-invasive method of classifying the severity, progression, and response to treatment of SM, and at North Carolina State University, Olby and Cerda-Gonzalez are evaluating the dynamics of cerebrospinal fluid flow in CKCS.

Information for this topic, "Syringomyelia in Cavalier King Charles Spaniels", was excerpted from www.CavalierHealth.org and the referenced scientific literature.

[References: Rusbridge, Vet Rec. 141:179, 1997; Rusbridge et al, JAAHA 36:34-41, 2000; Churcher,Child, Austr Vet J 78:92-95, 2000; Stern-Bertholtz, Sjšstršm, HŚkanson, J Sm An Pract 44: 253-256, 2003; Rusbridge, Knowler, Vet Rec 153:107-112, 2003; ibid, J Vet Int Med 18: 673-678, 2004; Vermeersch, Van Ham, Caemaert et al, Vet Rec, 154: 355-360, 2004.]