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Episodic Falling Syndrome

Episodic Falling Syndrome (EFS) is a condition causing the temporary inability to relax muscles resulting in collapse episodes which are usually a few seconds to several minutes long.

Found in

1 in 2,500 dogs

in our testing

Key Signs

Increased muscle tone, Spasticity, Collapse

Age of Onset

0 to 2 yrs

Juvenile onset


Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

Moderate-high likelihood

At risk dogs are likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with EFS

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about EFS

First signs of EFS can be seen in dogs 3 to 7 months of age. Episodic collapses are often associated with exercise, excitement, or stressful events, usually last a few seconds to several minutes, and resolve on their own. Episodic collapses begin with increased muscle tone leading to temporary immobility of the dog. The affected dog usually falls down with its limbs in an extended position. During an episode, an affected dog may exhibit bunny hop-like movements, have its back arched, and vocalize. The dog experiencing an episode stays fully conscious throughout. The severity and number of episodes vary over the course of the dog's life. Affected dogs appear neurologically normal between episodes.

Treatment is supportive care during the stiff/collapse episodes and limiting exercise, excitement, and stressful events to limit the occurrence of these episodes.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to be shown. A carrier dog with one copy of the EFS mutation can be safely bred with a clear dog with no copies of the EFS mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the EFS mutation. A dog with two copies of the EFS mutation can be safely bred with a clear dog. The resulting puppies will all be carriers. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the EFS mutation could develop due to a different genetic or clinical cause.

Technical Details

Variant Insertion
Chromosome 7
Coordinate Start 41,325,010
Coordinate End 41,340,730

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Forman, O. P., Penderis, J., Hartley, C., Hayward, L. J., Ricketts, S. L., & Mellersh, C. S. (2012). Parallel mapping and simultaneous sequencing reveals deletions in BCAN and FAM83H associated with discrete inherited disorders in a domestic dog breed. PLoS Genetics, 8(1). View the article

Gill, J. L., Tsai, K. L., Krey, C., Noorai, R. E., Vanbellinghen, J. F., Garosi, L. S., Shelton, G. D., Clark, L. A., & Harvey, R. J. (2012). A canine BCAN microdeletion associated with episodic falling syndrome. Neurobiology of Disease. View the article

Garosi LS, Platt SR, Shelton GD. Hypertonicity in Cavalier King Charles Spaniels. J Vet Intern Med 2002; 16:330. View the article