Episodic Falling Syndrome (EFS) is an inherited condition affecting Cavalier King Charles Spaniels. Episodes usually begin between 14 weeks and 4 years of age and are often associated with exercise, excitement or frustration. However, these episodes can occur at any time or under any circumstance. EFS is a disorder of the muscles that causes increased muscle tone and muscle spasticity (especially those of the limbs) resulting in limbs that appear “locked” in an extended position. This muscle spasticity results in a characteristic “praying” position and/or collapse. Episodes are usually a few seconds to several minutes in length and resolve on their own. Affected dogs appear neurologically normal between episodes. The severity and number of episodes vary over the course of the dog’s life and do not follow a specific progression pattern.
Breed-Specific Information for the Cavalier King Charles Spaniel
The Mutation of the BCAN gene associated with episodic falling syndrome has been identified in the Cavalier King Charles Spaniel. Though the exact frequency in the overall Cavalier King Charles Spaniel population is unknown, 13% out of 155 nonclinical Cavalier King Charles Spaniels from the United States were carriers of the mutation.
Genetic testing of the BCAN gene in Cavalier King Charles Spaniels will reliably determine whether a dog is a genetic Carrier of episodic falling syndrome. Episodic Falling Syndrome is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the BCAN gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Cavalier King Charles Spaniels that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
Gill JL, Tsai KL, Krey C, Noorai RE, Vanbellinghen JF, Garosi LS, Shelton GD, Clark LA, Harvey RJ. A canine BCAN microdeletion associated with episodic falling syndrome. Neurobiol Dis. 2012 Jan; 45(1):130-6.
Herrtage ME, Palmer AC. Episodic falling in the cavalier King Charles spaniel. Vet Rec. 1983 May 7; 112(19):458-9.