The latter stage is the deepest and is associated with vivid dreams during which a dog may shake and twitch, typically for a brief moment. If they’re particularly excited or disturbed by their dream, they may howl or bark as they shake.
Several medical conditions may cause a dog to shake or twitch. When they’re sick, dogs can feel discomfort and react badly to the illness.
If your dog’s shaking looks more like trembling and shivering, they may feel cold. Usually, they will tuck their tail and curl themselves up into a furry ball when they’re chilly.
It’s not common for dogs to have seizures, but it’s definitely something you need to look out for. Seizures last longer than regular shaking and are typically characterized by stiff and rigid muscles.