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While this set of symptoms may seem complicated, one veterinarian has told us that EFS looks like "nothing else". 

EFS is an 'exercise-induced hypertonicity disorder' meaning that there is increased muscle tone and the muscles are unable to relax.  Episodes will be in response to excitement, exercise, or frustration, except in severe cases.  Then symptoms may be chronic or happen with no apparent cause.  

Episodic Falling Syndrome displays itself as an array of symptoms so it is not easy to describe.  Each dog will have it's own expression of the disorder.  The frequency, type and/or severity of episodes may increase, decrease or change as the dog gets older.  Therefore, there is no pattern to the progression of EFS.  

If a Cavalier has one episode, however mild, then that dog should be assumed to be affected and a DNA test administered.

EFS events can range from momentary to very extended periods, depending on the dog and the degree of stress causing the symptoms.  In a few rare cases, dogs have been unable to recover from an episode.  A correct diagnosis is important to help alleviate the symptoms if possible.  While symptoms usually arise by five months of age, first notable symptoms can occur at any age.  EFS can occur in all colors and both sexes. 

Your dog may be screened for other disorders by your veterinarian.  Some symptoms may seem similar to those of Syringomyelia, a liver shunt, epileptic seizures or other disorders.   However, if EFS is suspected the DNA test is a less expensive option compared to a neurological or other workup.  Please see the contact page for a link to further information on Syringomyelia and epilepsy.  "Fly catcher's syndrome" is not known to be related to EFS but may occur in an affected Cavalier.

Description of Symptoms

During episodes the dog is aware, conscious and is sometimes able to react to stimuli.  There is no loss of bodily function. 

Episodes may include one or any combination of the following:

*  Freezing momentarily
*  Freezing or walking with the head down and to one side. 
*  Stiffness in the back legs
*  An apparent lack of coordination in the rear or front limbs
*  A bunny-hopping gait
*  Roached back with stiff back legs (may be a sign of back injury)
*  Temporary loss of control in the hind legs
*  Attempting to rise only to fall
*  Rolling or somersaulting
*  Laying on one side with the back legs extended, limbs may twitch
*  Apparent 'spasm'
*  Drooling
*  Retraction of the front legs, sometimes over the head
*  Tightening of the muscles around the mouth with an inability to open the jaws
*  Eyes may appear to bulge as the muscles of the face contract.
*  The 'deer stalker' position where the front legs contract and the rear legs stiffen (see the video of Penny)
*  Chronic tenderness and stiffness may exsist in extreme cases. 

After episodes, dogs with mild symptoms usually continue as if nothing has happened.  If the episode is severe or lengthy, some panting may occur and the dog may rest  and sleep.  After severe episodes some puppies become frightened and take some time to calm down.  Most get used to the events with age.

EFS does not seem to affect temperament.  

Please see the FAQ page to see what to do if you think that your dog is having an episode.  If your dog is having an extended episode or severe frequent episodes, contact your veterinarian immediately.



Please note that, if you have trouble seeing the videos here, you can access the first three videos on youtube by sorting on cavalier episodic falling:

Penny is extremely affected with EFS and other dogs may have different symptoms. The episode she is having lasted approximately four minutes.

Penny will be stressed in this video by the slight
movement of a towel in order to show you that she is conscious. Normally we are careful to keep things calm and hold her comfortably wrapped in a towel or laying on a cooling bed when she can't pant.  This seems to alleviate the stress and some say may shorten the episode. It certainly will ease the owner's stress if it comforts the dog.

If you have a dial-up connection, the 30 second version is available and will take about two minutes to load. The second video is one and a half minutes long and is a 6.6 MB file which will provide better quality. The longer version is an example of an entire episode, but the 30 second version may be useful for review. Quicktime version 4 or 6 is required and is available if needed at no cost.

Quicktime Pro is NOT required.

Please be patient with the time the movie takes to load.

30 Second video version (4.50 KB)

90 Second video version (3.21 MB)


Happy displays the falling and rolling symptoms that gave EFS it's name.  Happy has these episodes whenever he is excited.

Please be patient with the time the movie takes to load.

30 Second video of Happy (2.5 MB)

If you don't have it, Quicktime Movie software can be uploaded at no cost from:


Luc displays three of the less severe symptoms you might miss in a puppy if he were to do one of these behaviors for a short time.  First, he will stumble.  Some puppies get right up after these stumbles but Luc continues to reach for his toy.  In the second part of the video, notice that Luc's back legs are very straight and that he has a roach in his back and a very stiff gait.  Sometimes the puppy's hind legs will even cross.   In the third part of the video, even though he is being called, he is frozen.  Luc's head is turned to one side and he is standing crooked.  Sometimes puppies will just freeze without any contortion of their bodies.

Please be patient with the time the movie takes to load.

30 second videotape of Luc (1.6 MB)

If you don't have it, Quicktime Movie software can be uploaded at no cost



A video of Thistle, who displays different symtpoms from the videos above is available at the bottom of her own webpage at:


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Cavalier Episodic Falling