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Proof Chiari-like malformation can cause significant pain in dogs

New study conducted at Fitzpatrick Referrals provides clarity on the recognition and signs of canine Chiari-associated pain.


Charlie, a cavalier King Charles spaniel, with Chiari-like malformation-associated pain. Left: on a good day, right: on a bad day.

A study based at Fitzpatrick Referrals has found canine Chiari-like malformation (CM) can cause significant pain and impact on activity, temperament and sleep.

Lead author Clare Rusbridge was inspired to conduct the study because of lack of clarity on the recognition and diagnosis of the clinical signs associated with CM as opposed to syringomyelia (SM).

Irreversible damage

CM is an abnormality in the skull, making it smaller and impacting on the brain to alter the flow of CSF; this results in pain and a collection of fluid pockets within the spinal cord.

These fluid pockets are commonly known as SM and, over time, can cause irreversible damage to a dog’s spinal cord. However, it is not clear whether signs of pain in affected dogs are due to CM or SM, or both.

Five-year study

To try to rectify this, Prof Rusbridge studied the medical records of all the cavalier King Charles spaniels diagnosed with CM-associated clinical signs presenting to her at Fitzpatrick Referrals (partner practice of the University of Surrey School of Veterinary Medicine) during a five-year period.

She documented the historical and examination findings, and related them to the MRI findings, including presence and size of the SM.

Common signs

Prof Rusbridge found common signs in all dogs were:

  • vocalisation
  • spinal pain (neck, middle or lower back)
  • reduced activity
  • reduced stairs or jumping ability
  • aversion to being touched or groomed
  • altered emotional state (described as being more timid, anxious, withdrawn or aggressive)
  • sleep disturbance

A tendency to rub or scratch at the head or ears was common, but more likely in dogs with small or no SM, suggesting this may be a sign of head discomfort associated with CM.

Middle ear

Head and ear rubbing was not associated with the presence of material within the middle ear (a condition that is also common in this breed and often given the acronym PSOM).

The only signs that were specific to SM were phantom scratching, scoliosis (twisted spine) and weakness, and these were only present when the SM was large (at least 4mm wide).

Questionnaire

The study, published in the Journal of Veterinary Internal Medicine, is important because it suggests CM alone is a cause of pain in many dogs, and an aim is to use the information gained in this study to develop a questionnaire to determine the risk of CM and monitor the response to clinical signs.