What is Chiari Malformation in Dogs: Syringomyelia Awareness

My friend at Two Little Cavaliers blogs about Syringomyelia Awareness. She has a lot of important information about the condition and real-life stories.

The first time I heard about syringomyelia was during conversations with Annie, Ella’s mom. Ella had syringomyelia. As I learned about it, I was horrified at how much potential suffering this could mean.

I include some of the information here; please visit Two Little Cavaliers to read more.

What is Chiari Malformation in Dogs: Syringomyelia Awareness

Chiari Malformation (CM)

A Chiari Malformation (CM) occurs at the craniocervical junction.

This is where the skull and the top of the spine meet. At the skull’s bottom is a large hole called the foramen magnum. The foramen magnum allows the brainstem to exit the skull and become the spinal cord.

Schematic representation of Chiari-like malformation and syringomyelia. Image Today’s Veterinary Practice.

When the lower lobe of the brain, the cerebellum, is displaced to the level of the foramen magnum (mild CM) or through the foramen magnum (severe CM), there is overcrowding in the foramen magnum. This causes obstruction of the normal flow of CSF from the brain down to the spinal cord. As a result, many dogs with CM develop syringomyelia (SM).

Syringomyelia is a condition where cavities, or holes, called a syrinx, develop within the spinal cord.

The spinal cord is made up of grey and white matter. Using a computer network as an analogy, the grey matter can be considered the actual computer, whereas the white matter represents the network cables connecting the computers.

Syringomyelia Awareness: What is Chiari Malformation?

Clinical Signs

The most notorious symptom of CLM is excessive scratching. However, your dog might exhibit other symptoms.

In a study by Dr. Clare Rusbridge et al., they found that pain is related to syrinx width and symmetry.

Dogs with a more expansive, asymmetrical syrinx are more likely to experience pain, and dogs with a small, narrow syrinx may be asymptomatic.

Ventral Horn Damage

Syrinxes that damage the ventral horn, may result in neurological deficits such as:

  • decreased spinal reflexes
  • muscle atrophy
  • and limb weakness
Dorsal Horn Damage

Syrinxes that damage the dorsal horn of the grey matter are most likely to cause persistent pain. Dr. Clare Rusbridge also found that the larger the width of the syrinx, the more likely it was that the dog would exhibit:

  • pain
  • and scratching behavior

Intermittent pain might be more pronounced at night. The affected dogs might also be sensitive to touch near the neck, ear, and shoulder.

Both pain or scratching might worsen due to triggers such as:

  • touch
  • wearing a collar
  • movement
  • excitement

Further reading: Syringomyelia and Chiari-Like Malformation

Cavalier King Charles Spaniels are not the only breed that can suffer from this condition. Other susceptible toy breeds include:

  • Maltese
  • Yorkshire Terrier
  • Chihuahua
  • Brussels Griffon

Interestingly, Staffordshire Bull Terriers can also develop the condition, even though they are large dogs.

Bernard Williams’ “slosh” hypothesis

While neurologists learned a lot about the problem, the mechanism by which the resulting cavities form remained rather elusive. However, a 2021 study discovered that a neurosurgeon, Bernard Williams, might have had the answer since 1980–the “slosh” hypothesis.

He figured that the cavities form due to pressure changes such as from coughing, sneezing, and straining. The changes in pressure generate stress on the spinal cord tissue, causing the cavity to expand over time.

Further reading: http://Study discovers links to Bernard Williams’ 40-year-old “slosh” hypothesis

The discovery could improve understanding of the condition and help improve medical treatment.

For the complete article and images, please visit:
http://cavalierhealth.ca/PDF/Understanding_Canine_Chiari_Malformation_and_Syringomyelia.pdf

Categories: Chiari Malformation • Conditions • Syringomyelia

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Jana Rade

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience.

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