Chiari-Like Malformation (CLM) & Syringomyelia (SM)
Chiari-like malformation (CLM) is a condition where a dog’s skull is too small for its brain, leading to compression and abnormal cerebrospinal fluid (CSF) flow. This can cause a secondary condition called syringomyelia (SM), where fluid-filled cavities form within the spinal cord. These changes can result in pain and a variety of behavioural or neurological symptoms. CLM and SM can affect any breed of dog.
Pain-Related Symptoms
Sudden yelping or crying out, often during movement or handling
Neck pain or stiffness; reluctance to move head or neck
Decreased playfulness or energy levels
Reluctance to exercise, jump, or go up stairs
Preference to sleep with head elevated (e.g., on pillows or furniture)
Pain episodes that include freezing, hunching, or rolling
Pain that worsens at night, in the morning, or with temperature changes
Characteristic Behaviours
Phantom scratching ("air guitar") – scratching at neck/shoulder without contact
Excessive face rubbing on floors or furniture
Paw licking (often excessive)
Sensitivity to touch – flinching or yelping with gentle handling
Avoidance of collars or grooming around neck/head
Neurological Signs
Wobbly gait (ataxia), especially in hind limbs
Weakness or limping in one or more limbs
Uncoordinated or "drunken" walking
Delayed paw replacement (slower correction of turned-over paw)
Scoliosis (visible spinal curvature)
Head tilt or tremors (less common)
Torticollis (twisted neck posture)
Muscle atrophy in affected limbs
Sensory and Behavioural Indicators
Startle response to sound or movement
Confusion or distraction during activity
Avoidance of petting or touch (especially head and neck)
Snapping or growling when painful areas are touched
Increased irritability or withdrawn behaviour
Uncommon or Secondary Signs
Seizures (rare; may be unrelated or due to concurrent conditions)
Facial paralysis or partial deafness (rare, possible nerve involvement)
Visual or balance issues in advanced cases
Important Notes for Owners
Pain is often chronic and neuropathic (burning, tingling, or stabbing sensations)
Some dogs with CLM/SM may not show symptoms, even with MRI-confirmed diagnosis
Behavioural changes may mimic anxiety or aggression, but are often pain-related
Neurological symptoms can progress over time if untreated
What to Do If You Notice These Signs
Document symptoms and changes in behaviour
Consult your veterinarian promptly
Pain relief and neurological medications (e.g., pregabalin, gabapentin, omeprazole) may help
Avoid neck pressure (use a harness instead of a collar)
Consider referral for MRI and specialist evaluation if symptoms persist or worsen
Aggressive behaviour associated with CLM and Syringomyelia
Dogs with CLM/SM often experience neuropathic pain, particularly around the neck, shoulders, and head. They may react defensively or aggressively if touched in painful areas—especially if touched suddenly or during sleep. This may be interpreted as "snapping without warning," when in fact the dog is trying to protect itself from anticipated pain. Many affected dogs are hypersensitive to sound or touch and may startle easily. This heightened arousal can tip over into reactivity or growling, particularly in high-stress or noisy environments. Sudden movement, leaning over the dog, or picking them up can trigger what looks like unprovoked aggression. Just like people, dogs in chronic pain may have a lower threshold for stress or frustration. This can result in a dog that was previously friendly becoming grumpy, withdrawn, or snappy—especially around other animals or children.
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