CENTRAL nervous system disorders which result in involuntary skeletal muscle activity in a fully conscious individual are collectively referred to as movement disorders or dyskinesias (Adams and others 1997). Although rarely described in the veterinary literature (Meyers and others 1969, Woods 1977, Herrtage and Palmer 1983, Nakahata and others 1992, movement disorders are a well-documented group of diseases in human neurology and usually occur as a result of dysfunction of the extrapyramidal motor system that can have a variety of causes, both genetic and acquired (Watts and Koller 1997). The broad range of signs associated with movement disorders are classified into separate clinical entities on the basis of the rate of the involuntary skeletal musde activity. At one end of the spectrum, dystonia describes sustained involuntary muscle contraction, next comes athetosis, a slow writhing movement, then chorea, arrhythmic, jerky movements, and finally ballism, a rapid, flinging movement ofthe limbs. These conditions can be further divided into those that occur continuously and those that are episodic or paroxysmal. The latter can either occur spontaneously or can be induced by a variety of stimuli such as movement (in which case they are described as kinesogenic) or excitement (Marsden 1996). This short communication describes a new condition in boxer pups characterised by episodic involuntary skeletal muscle activity with normal levels of consciousness that bears some similarity to the human condition descriptively referred to as paroxysmal dystonic choreoathetosis (PDC).The first litter of six pups (four male and two female) was presented at between five and nine months ofage with a history of unusual neurological episodes. The severity of the problem varied between members of the litter and, in general, episodes occurred with greater frequency in the males than in the females. The most severely affected male had up to 10 episodes per day while the least affected female had only two episodes in six months. The episodes were first observed by the owners one to eight weeks after purchase at eight weeks of age and increased in frequency over the following months. Several of the owners reported that the episodes were induced by stimuli that caused the pups to become excited (such as ringing doorbells, playing with children and flashing lights), but there were no consistently identifiable triggers. It was also found that stroking and calmly talking to the dog could reduce the length of an episode.The authors were able to observe episodes in four of the litter during hospitalisation. Although no two episodes followed an identical pattem, several common features could be identified. These included an initial unilateral facial dystonia or twitching, producing a grimacing expression, lifting of an extended thoracic limb which was either held elevated for several seconds or banged to the ground in a series of rapidly repeated movements (Fig 1), unilateral dystonia ofthe neck and truncal muscles producing a torticollis post...

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