Dogs are prone to peculiar behaviors, from digging in their beds to resting a paw on your arm. These quirks even extend to when they’re sleeping, as dogs are liable to move and twitch their legs as though they were dreaming about running. Is that really what’s happening?
In very young puppies, “running” might actually be simple muscle twitching, a common trait in developing canine bodies. But if your dog is getting older and still moves its legs, it’s very possible it’s reacting to a dream in which it’s running toward something. While we can’t know for certain whether dogs dream, we do know they experience both REM and slow-wave sleep, with REM being a deeper stage of sleep where, at least in humans, dreams occur. Because dogs spend less time in REM than humans—roughly 10 percent of their total time sleeping, as opposed to a human’s 25 percent—they usually sleep more, which is why your pet might be conked out throughout the day and night.
In REM sleep, dogs may react to their dreams by moving their legs, whimpering, or even barking. These responses are more typical if dogs remain in REM sleep, which means they’re not constantly being aroused by commotion from visitors, kids, or other pets in the house.
Some pet owners see muscle jerking or spasms and get concerned the dog might be experiencing a seizure. But seizures can happen with the dog awake or asleep, and are often accompanied by open eyes. If your dog simply twitches while napping, chances are he’s just dreaming about a stick, a Frisbee, or a good time with his owner.