Effects of Narcolepsy
Dogs are infamous for their frequent napping habits. While naps are quite normal for domestic dogs, sometimes excessive daytime sleepiness is caused by a medical condition called narcolepsy. Narcolepsy is a syndrome in which the sleep-wake cycle is disrupted, causing tiredness, lethargy and brief periods of muscle paralysis or unconsciousness.
Symptoms of Narcolepsy in Dogs
Dogs suffering from narcolepsy periodically (and abruptly) fall into a state of deep sleep during normal waking hours. They often become partially or completely immobilized, and then spontaneously recover. Narcolepsy is neither life-threatening nor painful. Affected animals usually develop one or more of the following symptoms:
- Excessive daytime drowsiness
- Prolonged periods of sleep during the daytime
- Rapid onset of periods of deep sleep, lasting seconds to minutes
- Collapse into lateral (lying on the side) or sternal (lying on the stomach) recumbency
- Difficulty rousing from sleep
- Abrupt loss of consciousness
- Abrupt return to consciousness or wakefulness (usually spontaneous)
- Paralysis (partial to complete; “cataplexy”; often involves the lower legs or the head and neck)
- Muscle twitching (especially around the face, eyes and lower limbs)
- Rapid eye movements (REM sleep)
Narcolepsy in dogs is characterized by a condition called cataplexy, which involves brief episodes of partial or complete muscle paralysis with loss of reflexes. Cataplectic episodes are almost always completely and spontaneously reversible. The dog may develop weakness and/or twitching in its leg muscles, and its facial and neck muscles may also be affected. Narcoleptic episodes often occur during times of activity, such as eating, playing, running or other periods of excitement. For example, a dog playing fetch with its owner might suddenly fall into an apparent deep sleep, and then rise and recommence playing as if nothing has happened. These “sleep attacks” tend to be short (seconds to minutes), although they can last up to 30 minutes or more. Most affected dogs can be roused by loud noises, petting, calling their name or other forms of external stimuli. The frequency of narcoleptic symptoms depends upon the severity of the condition in a given dog. Some dogs experience only a few narcoleptic bouts each week or month, while others have dozens of episodes daily. Signs of narcolepsy can mimic signs of other, more serious conditions such as heart disease, diabetes and epilepsy.
Dogs at Increased Risk
Narcolepsy has been diagnosed in many breeds and has an established hereditary component. Predisposed breeds include the Labrador Retriever, Poodle, Dachshund and Doberman Pinscher. Symptoms usually appear by 6 months of age. Small-breed dogs seem to be more severely affected.