Episodic Falling is a form of muscular hypertonicity.
Muscular hypertonicity is a neurological condition where the muscle tone becomes rigid and unable to relax. Muscular hypertonicity has been reported in other breeds (Scottish Terrier, Norwich Terrier, Jack Russell Terrier, Yorkshire Terrier, Wheaton Terrier, Border Terrier, Bichon Frise, Boxer and Springer Spaniel), and a similar condition known as hyperexplexia or startle disease in humans as well. In other breeds it may be known under different names such as Scotty Cramp, Hyperkinesis and Paroxysmal Hypertonicity Disorder.
In Cavaliers it is known as Episodic Falling. Age of onset for Cavaliers is typically between 3 and 7 months, though an affected dog usually continues to have episodes throughout its life. Episodes can last from a few minutes to 15 minutes and the dog is usually clinically normal between attacks. It is not considered fatal though veterinary assistance should be requested if the episode is prolonged.
Episodes may be triggered by periods of exercise of varied duration, stress, heat and excitement.
Episodic Falling may initially be mistaken for epilepsy but the main difference is that the dog remains conscious and aware and there is no loss of bodily functions during the event. Symptoms and duration can be varied but some of the symptoms of an event can be:
- Laying on one side with the back legs extended, limbs may twitch
- Short periods of “freezing”
- Lack of coordination in the rear or front limbs
- A ‘deer stalker’ position
- A bunny-hopping gait
- Falling and unable to rise
- Loss of control of rear limbs
- Laying on side with rear legs extended; occasionally with twitching
- Intense face rubbing prior to the episode
- Inability to open jaws as the muscles tighten around the jaw
Treatment and management
Dogs with this condition generally have no after affects after an event and tend to live normal lives between episodes. During an episode the dog should be kept calm and cool as overheating can be an issue. There are medications can be used such as Diazepam and Clonazepam, however the side effects may outweigh the benefits.
This condition is caused by an autosomal recessive mutation and a DNA test to identify dogs which are clear, carriers and affected has been developed by the Animal Health Trust in the UK.