Episodic Falling Syndrome
Episodic Falling Syndrome (EFS), also known as episodic hypertonicity or muscle hypertonicity, is a genetic condition that only affects Cavaliers. The condition is due to a mutation in the BCAN gene that leads to the inability to relax muscles after exercise. This will cause the dog to freeze and then fall down.
The condition can first appear anywhere between 4 weeks and 4 years of age. Some Cavaliers may fall on their front legs (bunny hopping), while others may fall on all four legs. Falling episodes are typically triggered by excitement, exercise, or stress.
Key Facts
- Caused by a mutation in the BCAN gene — unique to the Cavalier breed
- Triggers include excitement, exercise, and stress
- Most dogs with EFS have a normal life expectancy; episodes often stop on their own
- EFS is recessive — DNA testing of breeding dogs prevents passing it to offspring
The majority of dogs with EFS have a normal life expectancy, and the signs are variable. In many cases, the episodes stop on their own after a few minutes. Some dogs can experience one or two episodes in their lifetime, while others experience frequent episodes. In severe cases, dogs need medical management.
EFS is a recessive gene disorder. This means that a dog must inherit two copies of the mutated gene to be affected. DNA testing of breeding dogs can prevent this from being passed to offspring. Some dogs carry one copy of the gene (carrier) but do not show any clinical signs. These carriers can pass the affected gene to offspring, so testing is essential.
Sources & Further Reading
- Cavalier Health — Episodic Falling Syndrome
- Forman et al. — A Missense Mutation in BCAN Disrupts Proteoglycan Clustering and Is Associated with Episodic Ataxia in the Cavalier King Charles Spaniel (PLOS Genetics, 2012)
- Penderis J., Bhatt K. — Epileptiform disorders in the cavalier King Charles spaniel (Veterinary Clinics of North America, 2007)
