Skull and Spinal Cord Abnormalities in Dogs

Syringmyelia and Chiari Malformationin Dogs

Chiari-like malformation is a disease in which one of the hollow spaces in the skull remains narrow or small and fails to grow in size. This causes the parts of the brain surrounding this area to be displaced into the opening at the base of skull through which spinal cord passes. Due to a protrusion of brain parts into this opening, the normal flow of cerebrospinal fluid (CSF) is obstructed.

One of the consequences of this obstruction is a disorder called syringomyelia, the development of fluid-filled cavities, or cysts, within the spinal cord. These disorders may develop due to underlying health problems, but they have also been found to hereditary links in some breeds. Toy breeds including the Cavalier King Charles Spaniels, King Charles Spaniels, and Brussel Griffons are at an increased risk for developing this condition. This condition has also been reported in Staffordshire bull terriers.

Symptoms and Types

• Crying during defecation or posture changes
• Distress during moments of normal excitement
• Intermittent pain (more severe at night)
• Sensitive to touch at shoulder, neck, ear, and sternum areas
• Scratching or pawing at shoulder, ear, neck, or sternum
• Scratching is more pronounced while walking and may be triggered by neck collar or excitement
• Head pressing due to head pain
• Neck pain
• Uncoordinated walk, apparent dizziness, wobbly eye movements
• Weakness, muscle fatigue
• Lethargy, loss of consciousness

Causes

Although syringomyelia is typically inherited, it can also develop in conjunction with conditions that lead to cerebrospinal fluid (CSF) flow obstructions, such as tumors.

Diagnosis

Your veterinarian will conduct a complete physical examination after taking a detailed background and medical history from you. You will need to give your veterinarian a detailed description of the onset of your dog’s symptoms, and the types of symptoms your dog has been experiencing. The more information your doctor has from the start, the quicker treatment can begin. And because this is a serious condition that requires immediate treatment, you will need to be as conscious of details as possible.

The results of the routine laboratory results, including the complete blood count, biochemistry profile, electrolytes, and urinalysis are often found normal in affected patients. Because of the location of the pain, diagnostic imaging will be necessary. X-rays of the brain skull may show abnormalities related to this condition, but magnetic resonance imaging (MRI) is the imaging tool of choice for a confirmatory diagnosis, since it gives a much clearer image of the interior of the skull. The results of the MRI may show an abnormal protrusion of brain parts into the passage of the spinal cord and other related abnormalities, or may show the presence of a cyst or tumor.

Your veterinarian may also take a sample from the cerebrospinal fluid that baths the brain and spinal cord in order to test the pressure of the fluid.