There is a condition we occaisionally see in the breed my wife and I show and breed (Cavalier King Charles Spaniels) called Episodic Falling. Don't know if it occurs in other breeds, but it sure sounds like what you are describing. Sorry I don't have any links, but if you do a search, you should be able to find plenty of information on it. Been a couple years since I read about it, but if I recall, Episodic Falling is not a terrible, awful disease. Good luck.

Bruce

OK, Ifinally found theweb site that describes Episodic Falling in Cavaliers: http://www.cavalierepisodicfalling.com Like I said, don't know if this occurs in other breeds.