Twitching occurs during REM sleep, when dogs dream. Their muscles tense as if acting out dreams.
Dogs may dream about normal dog behaviors like chasing, biting, and running. This causes twitches.
Some breeds like terriers are prone to active sleep related to their energetic temperament.
Puppies and seniors are more restless sleepers. Developing and aging brains prompt vivid dreams.
Twitching alone is normal. But see a vet if paired with whining, barking or waking up frightened.
No Cause for Concern
Slight noises or movements may partially rouse your dog, blending sleep and wakefulness.
Dogs seek heat regulation in sleep. Shivering and twitching helps adjust their body temperature.