Syringomyelia is a condition in which fluid-filled cavities, called syrinxes, form inside a dog’s spinal cord. It occurs when the normal flow of cerebrospinal fluid (the liquid that surrounds and cushions the brain and spinal cord) becomes blocked or disrupted, most often because the skull is too small for the brain. The condition is most common in Cavalier King Charles Spaniels, with a prevalence of 27% to 46% depending on the population studied, but it also affects other small breeds. Syringomyelia can range from silent and symptom-free to a source of significant, lifelong neuropathic pain.
How Syringomyelia Develops
In most dogs, syringomyelia traces back to a related skull abnormality called Chiari-like malformation. The core problem is a mismatch: the back of the skull is too small relative to the brain tissue it contains. This overcrowding pushes the lower part of the brain (the cerebellum) toward and sometimes through the opening at the base of the skull, called the foramen magnum. That opening is the main passageway for cerebrospinal fluid flowing between the brain and spinal cord.
When the cerebellum crowds into that space, it partially blocks normal fluid circulation. The disrupted flow creates abnormal pressure dynamics in the spinal cord, and over time, pockets of fluid accumulate within the cord itself. These fluid-filled cavities are the syrinxes. The condition is multifactorial, involving a shortened skull base, abnormalities at the junction between the skull and upper spine, and possibly other structural factors researchers haven’t fully mapped yet. It is not caused by a single defect in one bone.
Breeds Most at Risk
Cavalier King Charles Spaniels are by far the most affected breed. Studies report that 39% to 46% of the breed develop syringomyelia overall, though screening and selective breeding programs in the Netherlands and Denmark have brought that figure down to around 27% in the most recent generation of screened dogs. Other small, short-skulled breeds at elevated risk include Griffon Bruxellois, Chihuahuas, Affenpinschers, and Pomeranians. The condition is heritable, meaning it passes from parent to offspring through genetics.
Signs and Symptoms
Some dogs with syringomyelia never show symptoms, and the condition is only discovered incidentally on an MRI. When signs do appear, pain is the dominant feature, and it often looks different from what owners expect.
The hallmark behavior is “phantom scratching,” a repetitive scratching motion directed toward one shoulder or the side of the neck, where the paw never actually touches the skin. This action has a sudden, involuntary quality and can be triggered by excitement, movement, or even light touch from a collar or harness. For some dogs, leash walks become difficult because contact from the collar triggers an episode. Phantom scratching signals nerve damage inside the spinal cord and, when frequent, significantly reduces quality of life.
Other common signs include:
- Vocalization: yelping or crying out suddenly, especially when being picked up or changing position
- Reluctance to exercise or play
- Rubbing or scratching (with skin contact) at the back of the head or ears, once ear disease has been ruled out
- Sensitivity to touch around the head, neck, or shoulders
- Scoliosis: a visible curve in the spine
- Weakness or unsteady gait, particularly in more advanced cases
Dogs with the underlying skull malformation but without syrinxes may still show pain. These dogs tend to scratch toward the ears and head with full skin contact and may cry out during or just before scratching.
Diagnosis
Syringomyelia is diagnosed with an MRI scan of the brain and upper spinal cord. This is the only way to visualize the fluid-filled cavities inside the cord and to assess the degree of skull overcrowding. A standard veterinary exam can raise suspicion based on symptoms and breed, but it cannot confirm the diagnosis. MRI also helps distinguish syringomyelia from other causes of neck pain or scratching behavior, such as disc disease or allergies.
Medical Management
Treatment depends on how severe the symptoms are. Many dogs are managed with medication rather than surgery, especially when pain is mild to moderate. Three categories of drugs are commonly used.
The first line for nerve-related pain is gabapentin, a medication that dampens abnormal nerve signaling. It’s typically given two to three times daily. For flare-ups of severe pain that don’t respond to gabapentin alone, a short course of a corticosteroid like prednisone may be added, which helps by reducing inflammation and targeting specific pain-signaling chemicals in the central nervous system. Standard anti-inflammatory pain relievers (NSAIDs) and other pain medications can also play a role.
A second approach targets the fluid itself. Medications that reduce the production of cerebrospinal fluid can lower pressure inside the spinal cord. These are sometimes used alongside pain medications, particularly if the syrinx is large or symptoms are progressing.
Medical management does not cure syringomyelia. The goal is to control pain and maintain quality of life, and many dogs need lifelong medication with periodic adjustments.
Surgical Options
Surgery aims to restore normal fluid flow by creating more space at the back of the skull, a procedure called foramen magnum decompression. A recent study of 87 small-breed dogs treated with a modified surgical technique found that 87% showed sustained long-term improvement over a median follow-up period of about three years. Only 13% needed to continue medication after surgery due to recurring signs, and none required a second operation.
Those are encouraging numbers, but the picture is more complicated across the broader research. Other studies paint a less optimistic outcome: while most dogs improve after decompression, the syrinx itself does not resolve, and many dogs continue to show signs of neuropathic pain after surgery. Between one-quarter and one-half of surgically treated dogs experience a return of symptoms over time. Surgery is generally reserved for dogs whose pain is not adequately controlled with medication or whose neurological function is declining.
Long-Term Outlook
Prognosis varies widely. Dogs with mild or no symptoms can live normal, comfortable lives with monitoring alone. Among dogs with symptoms managed medically or surgically, roughly half to two-thirds improve or remain stable over time, while the remainder may gradually worsen. In one study tracking 15 dogs with Chiari-like malformation and syringomyelia, eight improved, two stayed stable, and five deteriorated, with 11 of 15 still alive at the end of the study period. Dogs whose syringomyelia stems from other causes, such as spinal trauma, tend to have a less favorable course.
The condition is progressive in many dogs, meaning it can worsen with age. Early detection and proactive pain management give dogs the best chance of maintaining a good quality of life long-term.
Home Care and Daily Adjustments
Small changes at home make a meaningful difference for dogs living with syringomyelia. The most important step is removing neck collars entirely and switching to a well-fitted harness, since any pressure on the neck can trigger pain or phantom scratching episodes. Raised food and water bowls help keep the neck in a neutral position during meals, reducing strain on the upper spine.
Keep exercise gentle and low-impact. Puzzle toys, nose work, and indoor fetch provide mental stimulation without putting stress on the neck and spine. Avoid activities that involve jumping from heights, and skip any training that requires the dog to look sharply upward. Maintain a healthy body weight, since extra weight adds load to the spine. Soft bedding supports comfort, and grooming should be done gently, especially around the head and neck, using soft brushes to avoid startling pressure. If your dog sees a groomer, look for one experienced with neurological patients.
Consistency matters. Dogs with syringomyelia do best with predictable, low-stress routines. Avoid temperature extremes, keep training sessions short and reward-based, and pay attention to subtle shifts in behavior that might signal increasing pain, such as new reluctance to walk, changes in scratching frequency, or unexpected vocalizations.
Screening and Breeding
Because syringomyelia is heritable, breeding programs play a central role in reducing its prevalence. The British Veterinary Association and The Kennel Club run a joint screening scheme that uses MRI scans of the brain and upper cervical spinal cord, graded by expert veterinary scrutineers. The results are used to guide breeding decisions. There are published breeding recommendations, though no estimated breeding values are currently available for the condition.
If you’re considering purchasing a puppy from an at-risk breed, ask to see the parents’ MRI screening results before committing. Breeders who participate in health screening programs and meet best-practice health standards are actively working to reduce the condition’s frequency. Dutch and Danish screening programs have already demonstrated that selective breeding can lower syringomyelia prevalence meaningfully within a single generation.