Can dogs have nightmares? Yes, they most certainly can! Most people who own dogs will have noticed that dogs have very animated sleep patterns, thy may twitch, bark, or even start running in their sleep. This gives a very obvious impression that they are dreaming about something, most likely chasing a rabbit. Actually, this is not far from true. A dogs brain is structured very similar to a humans, and they do dream. These dreams are not usually imaginations, but replays and reviews of what they have already done. So yes, dogs can dream, and dogs can also have nightmares.
It would actually be rather counter-intuitive if dogs did not dream, considering that animals with much less intelligence have been proven to dream. Dogs brains are actually very similar in structure and function to a humans brain, much more so than when compared to a rat or a lizard. We are actually very similar to our dogs in the way we think. Not only this, dogs display the same brainwave patterns and cycles of sleep that humans do, so it is totally reasonable to assume they are dreaming. Dogs have also been observed to start moving when they enter a state of REM sleep, and start showing beta waves. So yeah, they are chasing that bird in their sleep, and having so much fun doing it they might kick you in the face by accident. If you observe your dog as they fall to sleep, it is actually pretty easy to watch them progressing through the cycles of sleep! Unfortunately, some dogs can have bad dreams as well, which could result in some of the most terrible dog whines and screams you have heard out of your pet. Just like humans, dogs can have anxiety attacks, and get dreams so bad they wake up in panic. If this happens recurringly to your dog, you should take them to the vet to figure out what the issue is and how to solve it.