Cavalier King Charles Spaniel Health: MVD, Syringomyelia & SM

The Cavalier King Charles Spaniel is one of the most affectionate, adaptable, and genuinely sweet-natured dogs in existence. It is also one of the most medically challenging breeds to own responsibly. With a typical lifespan of 9–14 years — though many are affected by serious disease well before the upper end of that range — the Cavalier demands owners who are educated, financially prepared, and committed to frequent veterinary monitoring. This is not a breed for those who expect a low-maintenance companion.

Mitral Valve Disease (MVD): The Breed’s Greatest Crisis

Mitral valve disease is a degenerative condition in which the mitral valve of the heart — the valve between the left atrium and left ventricle — thickens, becomes irregular, and gradually fails to close properly. Blood leaks backwards with each heartbeat (regurgitation), placing increasing strain on the heart. As the disease progresses through its stages, the heart enlarges to compensate, and eventually congestive heart failure develops: fluid accumulates in the lungs (pulmonary edema), causing coughing, laboured breathing, and extreme exercise intolerance.

In most dog breeds, MVD is a disease of old age. In Cavaliers, it is an inherited condition that manifests far earlier and with far greater frequency than in any other breed. Studies published in peer-reviewed journals have documented that:

• Approximately 50% of Cavaliers have a detectable heart murmur by age 5
• Over 90% have a murmur by age 10
• Virtually all Cavaliers will develop MVD at some point in their lives

MVD is staged using the ACVIM (American College of Veterinary Internal Medicine) classification:

• Stage A: Breed at high risk but no disease detected yet
• Stage B1: Heart murmur present, heart not yet enlarged
• Stage B2: Heart murmur plus cardiac enlargement, still no symptoms
• Stage C: Active congestive heart failure (current or previous episode)
• Stage D: Refractory heart failure not responding to standard therapy

Critically, treatment with pimobendan is now recommended beginning at Stage B2 — before congestive heart failure develops — following the landmark EPIC trial. This medication has been shown to significantly delay the onset of heart failure. This makes early detection through regular screening essential: a dog in B2 can be treated; a dog in B1 that progresses to C without being monitored may collapse or die before treatment begins.

Mandatory Cardiac Screening Protocol

The MVD Breeding Protocol, developed by Cavalier breed clubs in collaboration with cardiologists, specifies that dogs should not be bred unless: they are at least 2.5 years old with no murmur, and both their parents had no murmur until at least age 5. This protocol, when adhered to by breeders, has been shown to reduce the incidence and age of onset of MVD in subsequent generations. Always ask breeders for documented cardiology certificates for the puppy’s parents and grandparents.

For owned Cavaliers: Annual cardiac auscultation by a board-certified cardiologist (not just a general practice vet) starting at age 1, every year without exception, is the minimum standard of care for this breed. Echocardiography is recommended for dogs with murmurs to accurately stage the disease and guide treatment decisions.

Syringomyelia (SM) & Chiari-Like Malformation (CLM)

Syringomyelia is a condition in which fluid-filled cavities (syrinxes) form within the spinal cord itself, causing damage to surrounding tissue. In Cavaliers, the underlying cause is Chiari-like malformation — a condition in which the back of the skull is too small for the cerebellum, causing the brain to be pushed partway into the opening of the spinal canal (the foramen magnum). This obstruction disrupts normal cerebrospinal fluid flow, leading to syrinx formation.

SM is alarmingly common in Cavaliers. MRI studies have found evidence of CLM in over 90% of Cavaliers examined, and syringomyelia in 30–70% depending on the study. Clinical signs of SM include: scratching at the neck, shoulder, or ear region with one hind leg (often called “phantom scratching” because the dog scratches at air), vocalising or yelping for no apparent reason, reluctance to be touched on the head or neck, scoliosis, weakness in the limbs, and extreme sensitivity to being picked up. The condition is painful and can be debilitating.

MRI is required for diagnosis. Treatment ranges from medical management (gabapentin, pregabalin, NSAIDs, omeprazole to reduce CSF production) to surgical decompression at the foramen magnum. Surgery may halt progression but does not always eliminate pain. Dogs with significant syrinxes often require long-term pain management.

Episodic Falling Syndrome

Episodic falling syndrome (EFS) is a paroxysmal movement disorder unique to Cavaliers, caused by a recessive mutation in the BCAN gene. Affected dogs experience episodes of muscle rigidity, hypertonicity, and abnormal postures — often appearing to “freeze” or fall when excited or exercising. Episodes typically begin before age 5 and can last seconds to minutes. EFS is distressing to witness but is not believed to be painful. A DNA test is available to identify carriers and affected dogs.

References

1. Boswood A, Görlich A, Gordon SG, et al. Effect of pimobendan in dogs with preclinical myxomatous mitral valve disease and cardiomegaly: The EPIC study — a randomized clinical trial. Journal of Veterinary Internal Medicine. 2016;30(6):1765–1779. PMID: 27678080
2. Rusbridge C, Greitz D, Bhatti SF. Syringomyelia: Current concepts in pathogenesis, diagnosis, and treatment. Journal of Veterinary Internal Medicine. 2006;20(3):469–479. PMID: 16734089