How a dog's behaviour can predict a painful spinal cord condition and its relevance to humans

What is it about?

Cavalier King Charles Spaniels are bred after a distinct head shape, creating a mismatch between the size of their skull and their brain, which overcrowds the junction between the brain and the spinal cord. Over time this can cause a condition called syringomyelia, characterized by the formation of fluid-filled cavities inside the spinal cord. Syringomyelia also occurs in people, and in both dogs and humans it can cause neuropathic pain. An MRI scan is the most reliable way to confirm syringomyelia and to see the extent and size of the cavities. However, MRI is expensive and not available everywhere, so many dogs will never get scanned. We therefore asked whether dog behaviours noticed by the owners could reliably predict the presence of a painful cavity that needed treatment. We studied 89 Cavalier King Charles Spaniels and interviewed their owners using a standardized questionnaire, and then compared the owners' answers with their dog's MRI scan. Some specific clinical signs turned out to be strong predictors of a large and clinically relevant cavity: "phantom" scratching (a scratching motion of the hindlimb toward the neck or shoulder that never touches the skin), real scratching towards both sides of the neck and shoulder, discomfort or aversion when the head or neck is touched, worsening of clinical signs such as scratching when the dog is excited or nervous, and a habit of sleeping with the head held in an unusual, often raised, position. Each of these clinical signs on its own was a good predictor, but the likelihood of a cavity increased further when some of them appeared in combination. Each of these clinical signs on its own was a good predictor, but the likelihood of a cavity increased further when some of them appeared in combination. We also found that dogs who showed scratching towards one side of the neck or shoulder tended to have a cavity on that same side. This parallels humans with syringomyelia, who often feel pain on the same side as a cavity when it extends more to one side of the spinal cord than the other.

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Photo by Izabelly Marques on Unsplash

Photo by Izabelly Marques on Unsplash

Why is it important?

For dogs, this gives veterinarians a way to identify animals that likely need care and start treatment even when an MRI is not an option, so that dogs in pain are less likely to be missed. That matters directly for animal welfare. The wider significance reaches beyond dogs. Cavalier King Charles Spaniels develop syringomyelia naturally, and their condition closely resembles the human disease. That makes them a rare, spontaneously occurring model of central neuropathic pain. Learning to read this pain from behaviour, and linking specific clinical signs to MRI results, helps bridge veterinary and human medicine.