Via The Center for Narcolepsy at Stanford School of Medicine], this video explains:
Various narcoleptic episodes in dogs. Sporadic cases of narcolepsy in dogs is due to hypocretin peptide deficiency while the familial form is due to mutations in one of the two hypocretin receptor genes (hcrtr2). Various dogs are shown here in a clip narrated by Dr. Emmanuel Mignot.
Or for the tabloid take, watch Skeeter the Narcoleptic Poodle from Inside Edition. "Skeeter's troubles staying awake are heartbreaking..."
Visit the Sleep Foundation to learn more.