Cavalier Episodic Falling Syndrome in Dogs

The seizure-like episodes of episodic falling syndrome (EFS) usually begin somewhere between 3 months to 4 years of age. Symptoms like rigid limbs, abnormal postures, loss of coordination, and collapse are not accompanied by a loss of consciousness. Your dog may seem completely aware of what is happening and will recover quickly after an attack. While some dogs can suffer permanent neurological injury, with rare cases of euthanization, this disorder usually improves with therapy and the lifespan is not affected.

Episodic falling syndrome is a type of paroxysmal dyskinesia, which are episodic movement disorders. This condition is characterized by episodic attacks of abnormal muscle movements, with normal behavior seen between attacks. It can be managed effectively with treatment, and is a common condition specific to Cavalier King Charles Spaniels.

Symptoms of EFS are directly related to the inability of the muscles to relax. They occur only during episodes which are generally triggered by exercise, stress, anxiety, excitement, or apprehension. Dogs show no abnormal signs between episodes, and appear mentally healthy. Symptoms can include:

• Rigid gait in rear limbs, similar to a bunny hop
• Muscle spasms in the limbs and trunk that gradually worsen
• Abnormal limb posture, such as a deer stalking or praying position
• Limb rigidity
• Stiffness 
• Stumbling
• Vocalization or yelping
• Arching of the back
• Loss of coordination
• Collapse, without losing consciousness
• Falling
• Overheating

Episodic falling syndrome is caused solely by a single mutated recessive gene that is associated with neurological function, the BCAN gene, and is unique to the Cavalier King Charles Spaniel. It is an inherited gene, which means that it is passed down from parents to offspring. While only a small percentage are affected by EFS, carriers are extremely common, and make up about 13% of the breed.

Most routine testing is not helpful in correctly diagnosing this condition, therefore diagnosis will depend on clinical signs, the specific breed of dog, and DNA testing. 

There are many other conditions that can cause the same symptoms as EFS. The main difference is that EFS episodes are usually triggered by excitement, stress, exercise or apprehension. The dog will remain conscious and will rarely have continuing discomfort or pain. Videos of episodes can help your veterinarian diagnose EFS correctly. If not available, give your veterinarian a report of your dog’s exact behaviors. This can prevent misdiagnosis and unnecessary testing, or any treatment with medications that can worsen the condition.

Suspected cases of EFS will have a blood sample taken and submitted for a genetic test that looks for the mutated BCAN gene. If the dog does not test positive for this mutated gene, it is not diagnosed with EFS. If two of the mutated genes are found, it is considered affected. If only one gene is found, it is a carrier. This information is critically important for breeders.

Episodic falling syndrome is rarely a life threatening condition, but it is lifelong. Some research has shown that mild cases can stabilize by age one.

Treatment for EFS is through medication, and is geared toward relaxing the muscle to stop the episodes from occurring. Clonazepam, an anticonvulsant and muscle relaxant, is the most commonly prescribed drug, and can be administered by itself, or with acetazolamide in more difficult cases. Taken orally, clonazepam treatment has seen a decrease in episodes, in one study from 25 to 30 per week down to one every two to three months, with dogs described as normal after treatment of two years.

Acetazolamide may also be prescribed, usually in more severe cases, and can result in a complete resolution of symptoms. It is administered with careful monitoring, as many dogs do not respond well to it. Improvement has also been seen with diazepam and fluoxetine, which has resulted in remission of symptoms.

Dogs can develop a tolerance for medication and the benefits may wear off. In cases where medication is not working, it can help to identify the triggers of your dog’s episodes and try to avoid them. Since this is a lifelong condition, continuous treatment is usually needed.

Dogs with episodic falling syndrome are usually not incapacitated and can be treated throughout their lifetime with medication. Recovery is good with treatment.

During an episode, comfort your dog by holding it gently, keep him cool, and do not attempt to force his legs into any position. Make sure your dog stays rested after the episode to prevent a reoccurrence.

Breeders should test for the BCAN gene and ensure that it does not get passed on to future generations. There are services that offer this DNA testing from a blood sample.