Narcoleptic canines display periodic leg movements during sleep

Periodic leg movements during sleep (PLMS) is a high prevalent sleep disord er of unknown etiology. The disease is pharmacologically treated with dopam inergic agonists (i.e. D2/D3 agonists) and opiates. Periodic leg movements during sleep often occur in narcoleptic patients. We observed that narcolep tic canines, like narcoleptic humans, also exhibit jerky, unilateral or bil ateral slow leg movements during sleep. The movements in dogs are character ized by repetitive dorsiflexions of the ankle, lasting 0.5-1.5 s, and occur at regular intervals of 3-20 s, thus showing similarities to PLMS in human s. The observation that D2/D3 agonists aggravate cataplexy in narcoleptic d ogs suggests that altered dopaminergic regulation in canine narcolepsy may play a critical role in both cataplexy and PLMS. Our canines may therefore be an invaluable resource in PLMS research.