Post by DogGoneGood on Aug 28, 2008 16:25:22 GMT -5
SYRINGOMYELIA
Syringomyelia (sir IN go my EEL ya) is a polygenetic (carried on several different genes that have to combine in particular ways) disease that affects small breed dogs, specifically the Cavalier King Charles Spaniel.
Syringomyelia (SM) is also known as "neck scratcher’s disease" because many dogs affected with SM shows signs by scratching at their neck, ears, and head or in the air around this area. Most commonly the dog will scratch this area while walking and cry in pain. A dog scratching at their head doesn't specifically mean it has SM, but should be checked by a vet if this does occur, especially if it is of any breed affected by this disease.
Unfortunately, SM is also misdiagnosed sometimes and labeled as allergies, ear problems, or spinal/disk problems. If your dog is a breed affected by this disease and has been diagnosed with any of these problems, and treatment does not seem to be helping please seek a second opinion. In fact, I would suggest seeking a second opinion even if the treatment appears to be working.
What Is Syringomyelia?
Syringomyelia is a potentially painful disease that is caused by skull malformation (Chiari-like malformation [CM]). This is similar to the Chiari malformation found in humans. Basically, the skull is too small for the brain which can cause the brain to squeeze, or herniated, through the spinal cord opening in the dogs skull. When this happens it obstructs the cerebrospinal fluid (CSF) circulating the brain and spine which causes pressure to rise. This in turn causes pockets of fluid (syrinxes) in the spinal cord that presses on nerves, which causes pain and disability.
Is There a Cure for Syringomyelia?
Unfortunately, no, there is no cure for SM. There is only treatment to alleviate pain, and preventative measures to try and breed this disease out of bloodlines. It is highly suggested to have your dog tested for SM as early as 2 and a half years of age up until it is 3 or 4 years old. Only dogs who do not show signs of SM should be bred.
Treatment:
Treatment for SM consists of drugs and surgery.
[1] Before the disease progresses to its severe form, the use of anti-inflammatory cortisteroids, such as prednisolone (Prelone), methylprednisolone (Medrol, Medrone), and dexamethasone (Decadron, Dexamethasone Intensol, Dexone, Hexadrol), or non-steroidal anti-inflammatory drugs (NSAIDs), such as carprofen (Rimadyl), Metacam, and aspirin, may relieve the symptoms but not the deterioration. Cortisteroids have serious side effects, such as weight, gait, and skin changes, and harmful suppression of the immune system. Long term use of these drugs is not advised.
NSAIDs and other conventional analgesic medications have not been found to be effective by themselves to relieve pain. Two 2007 studies (1) (2) show that the type of pain behavior suggests that the dogs experience neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn, and that, "as such it is likely that conventional analgesic medication may be ineffective."
Anticonvulsants, such as gabapentin (Neurontin, Gabarone), have been successful in some more severe cases. Gabapentin works through a receptor on the membranes of brain and peripheral nerve cells. It binds to calcium channels and modulates calcium influx as well as influences GABergic neurotransmission. Its effect is to deaden the irritated nerve impulses in the dog's neck. In humans, gabapentin reportedly does not interact with any other medications, and it is not metabolized, so it is fully excreted in the urine and has no affect upon the liver. However, in dogs, gabapentin is partially metabolized in the liver, and therefore the prescribing neurologist may be expected to order periodic blood tests to check the liver enzymes.
In human studies, gabapentin has caused side effects, including sleepiness, dizziness, and leg edema, which were minimized by increasing the dose gradually and by taking the drug with food. Gabapentin also may be given in combination with NSAIDs.
A newer anticonvulsant, pregabalin (Lyrica), is being prescribed by some neurologists in treating SM. It is closely related to gabapentin and was developed by Pfizer, which also developed gabapentin. Pfizer reports that pregabalin is more potent than gabapentin and achieves its effect at lower doses. Doses of pregabalin also reportedly have a longer lasting effect than gabapentin. No generic version is available, and as an exclusive brand, Lyrica is quite expensive in comparison to generic gabapentin.
Oral opioids (pethidine, methadone, tramadol) are alternatives to anticonvulsants. Methylsulfonylmethane (MSM) is recommended by some veterinary neurologists as a dietary supplement.
Surgery to allow the cerebrospinal fluid to flow normally may be necessary to reduce the pain and deterioration. Surgery is recommended if there is significant pain or a deteriorating condition. It usually is successful in significantly reducing the pain and improving the neurological deficits. Neurologists experienced with CM and SM in Cavaliers have found that early surgical treatment is more successful than waiting and considering it as a last resort, and that the longer the dog has been in pain, the less likely it will recover.
One form of surgery is called foramen magnum decompression (FMD), or suboccipital decompression, surgery. The surgeon removes the supraoccipital bone and the cranial dorsal laminae of the atlas. Decompression surgery may include incising through the dura sac, a tough membrane which contains the brain inside of the skull, and installing a dural graft or shunt, to allow more space for the cerebellum and to reduce the pressure of the flow of CSF. In some surgeries, the entire occipital bone also is removed. A less frequent surgical procedure is subarachnoid shunting, which essentially is a salvage operation when the surgeon has no other surgical options. All FMD surgeries are technically difficult and should be performed only by experienced neurological surgeons.
Although this form of surgery often is successful, it is very expensive, and many dogs either have a recurrence of the disease or still show signs of pain and scratching. Some post-operative pain is only temporary, due to leakage of CSF through the incision in the dura until that incision heals, or because the syrinx is still present after the surgery. The most frequent reason for recurrence reportedly is the development of post-operative scar tissue which compresses the cervicomedullary junction. Scar tissue has required additional surgery to remove it in as many as half of all FMD surgical cases. To avoid the development of scar tissue, it is important to not allow the dog too much freedom of movement or excitement during the healing process, which may last from three to six months.
How is Syringomyelia Diagnosed?
While not every dog with SM will show clinical and physical signs of SM, there are many signs of this disease. A sure way of determining whether a dog has SM or not is by Magnetic Resonance Imaging (MRI).
[li]restlessness
[/li][li]increasing reluctance to exercise
[/li][li]difficulty moving up and down furniture and uncoordinated movements in the early stages
[/li][li]uncontrollable urge to scratch the neck area and shoulders
[/li][li]hypersensitivity to the neck area (which may cause the dog to scream or yelp as a reaction to something as simple as a collar)
[/li][li]"air scratching" around the neck, head or shoulders
[/li][li]scoliosis (especially in young dogs), where the dogs neck and spine bend into a 'C'
[/li][li]weakness in the legs
[/li][li]sudden yelping for no reason
[/li][li]flipping around to bite at the hindquarters
[/li][/ul]
What Breeds are Affected by Syringomyelia?
I've yet to find a comprehensive list of what breeds are affected by SM, so I am attempting to compile my own. Please check back for an update of this list.
In the meantime, the most common breed highly affected by this disease is the Cavalier King Charles Spaniel, and secondly is the Brussels Griffon. French Bulldogs, Weimaraners, and German Mastiffs are also reported to be affected by this disease.
[2] Syringomyelia (SM) and Chiari-like malformation (CM) form a serious and widespread condition in cavaliers. Researchers think at least 90% of CKCS [Cavalier King Charles Spaniel] have the malformation and predict from 30-70% will eventually develop syrinxes (SM), making CM/SM a major concern for cavalier owners and breeders.
[li][1] CavalierHealth.org - Syringomyelia (SM) and the Cavalier King Charles Spaniel
[/li][li][2] The CKCS Syringomyelia (SM) Infosite
[/li][li]CKCS Syringomyelia News - Pedigree Dogs Exposed (see also, our DGGTF discussion on Pedigree Dogs Exposed )
[/li][li]GreatDogs.co.uk - Syringomyeliau
[/li][li] About Cavalier Health - Syringomyelia (SM)
[/li][li] Cavalier King Charles Spaniel Club of Canada - Health Articles - Syringomyelia
[/li][/ul]