Syringomyelia (SM) in Dogs: Symptoms, Causes, & Treatments

Syringomyelia (SM) in dogs is a severe, chronic condition that affects the spinal cord. When fluid-filled cavities or cysts — known as syrinxes — form within the central canal of the spinal cord, they can expand and cause damage to the spinal cord’s tissue. This process can lead to a variety of symptoms, ranging from mild discomfort to severe pain and partial paralysis. The condition is most commonly seen in certain toy breeds but can affect any dog.

There are different levels of severity in SM, classified as follows:

• Grade 0: This represents a normal condition where there’s no syrinx or pre-syrinx, and no dilation present.
• Grade 1: This involves dilation of the central canal that does not exceed two millimeters.
• Grade 2: This indicates the presence of syringomyelia, characterized by central canal dilation exceeding two millimeters and the presence of a pre-syrinx or syrinx.

Moreover, each severity level is further categorized by a letter that denotes the age of the dog, given that SM is a condition that progresses over time. The age categories are:

• A: Above five years of age
• B: Between three and five years of age
• C: Between one and three years of age

Here’s what you should know about the symptoms, causes, and treatments for the condition.

Symptoms of syringomyelia (SM) in dogs

Syringomyelia can manifest a variety of symptoms in affected dogs, and the severity can vary widely. The most common symptom is pain, which may be acute or chronic, depending on the progression of the disease. You may also notice your dog expressing discomfort through whining, yelping, or showing reluctance to move their neck or head. Another telltale sign is excessive scratching — particularly at the neck and shoulder areas — without making physical contact with the body. This behavior is sometimes referred to as “phantom scratching” because it appears as if the dog is scratching at an itch that isn’t there. Other symptoms to look out for include:

• Weakness or lameness in the limbs
• Changes in behavior
• Sensitivity to touch or sudden movements
• Muscle wasting
• Loss of balance
• Scoliosis — or curvature of the spine — visible in some advanced cases
• Seizures
• Paralysis

To accurately diagnose syringomyelia in your dog, your veterinarian will begin with a thorough medical history and physical examination. The most definitive tool for diagnosing SM is magnetic resonance imaging (MRI). An MRI can provide detailed images of your dog’s brain and spinal cord, allowing for the visualization of fluid-filled cavities within the spinal cord that are characteristic of syringomyelia. Due to the need for the dog to remain perfectly still during the procedure, general anesthesia is usually required to conduct an MRI safely.

It’s also possible that your vet might recommend other diagnostic tests — such as X-rays or a myelogram — to rule out other conditions that can mimic the symptoms of syringomyelia. That said, it’s crucial to follow through with these diagnostic steps if you notice any signs of discomfort or unusual behavior in your dog. Remember, early diagnosis can significantly influence the management and outcome of this condition.

Causes of syringomyelia (SM) in dogs

The primary cause of SM in dogs is related to a malformation of the skull, known as Chiari-like malformation (CM), where the back part of the skull is too small for the cerebellum. This results in the obstruction of cerebrospinal fluid (CSF) flow around the brain and spinal cord and can lead to the formation of syrinxes. Although the exact reason for the development of CM is not fully understood, it is widely recognized to have a genetic component.

Certain breeds are predisposed to developing SM due to their higher likelihood of having CM. These breeds include but are not limited to:

• Cavalier King Charles Spaniel
• Fox Terrier
• Pomeranian
• Pekingese
• Miniature Dachshund
• Maltese
• Cavapoo
• Cockalier
• Beaglier
• Cavachon
• Brussels Griffon
• Lhasa Apso
• Samoyed
• Yorkshire Terrier
• Chihuahua
• Pug

Apart from genetic predisposition, environmental factors, tumors, and injury may exacerbate the condition but do not constitute primary causes.

Treatments for syringomyelia (SM) in dogs

Treating syringomyelia in dogs focuses on managing the symptoms and improving the quality of life, as there is no known cure for the condition itself. Treatment options can include:

• Medication: Nonsteroidal anti-inflammatory drugs (NSAIDs), pain relievers, and medications that reduce CSF production can help manage symptoms. Gabapentin, an anti-convulsant drug, is often used to manage neuropathic pain. Additionally, your vet may also prescribe corticosteroids to reduce inflammation and swelling around the syrinxes.
• Surgery: In some cases, particularly when a Chiari-like malformation causes SM, surgery might be an option to alleviate the pressure on the spinal cord. The most common surgical procedure involves removing part of the bone at the back of the skull to create more space for the brain. This can help restore the normal flow of CSF and potentially reduce symptoms. However, surgery comes with its own risks and is not suitable for all dogs.
• Physiotherapy and rehabilitation: Physiotherapy and rehabilitative therapies — including hydrotherapy — can help maintain muscle strength and flexibility, providing relief from some symptoms. These therapies can also help manage pain and improve your dog’s quality of life.
• Regular monitoring: Regular check-ups with your vet are crucial for monitoring the progression of the disease and adjusting treatment plans as necessary. Advanced imaging techniques — such as MRI — are typically used to evaluate the effectiveness of treatment over time.
• Supportive care: Providing a comfortable living environment, ensuring your dog does not engage in activities that could exacerbate symptoms — such as using a harness instead of a collar — and keeping a consistent routine can all help manage SM symptoms.

If your pet is showing any signs of syringomyelia, or if they belong to a breed that is predisposed to SM, proactive veterinary care is essential. With proper management, many dogs with SM can lead happy, comfortable lives.