Why do dogs wag their tails in their sleep?

Dogs and puppies do many funny and unpredictable things that are both entertaining and confusing for humans. One of these is watching a dog wag its tail while sleeping or napping.

Watching your dog wag its tail while sleeping may be common for pet parents, especially during REM sleep when dogs are dreaming. They might even bark or move their legs like they’re running in place.

Whether you’re caring for Bordoodle puppies or an adult  Golden Retriever, this sight may alarm you the first time you see it.

But why does a dog wag its tail while sleeping? Is it because they’re having a good dream, or maybe a nightmare?

In this article, we’ll go into some of the most common reasons why a dog might wag its tail while sleeping and a few possibilities why you should pay attention to their sleep patterns.

Having a happy dream

One of the top reasons your pet’s tail wags in their sleep is because they experience a good dream that makes them happy enough to wag their tail while sleeping.

Your dog is having a fun dream and may move as if running. They may even bark quietly or make happy sounds if they’re having an exceptionally good dream.

In this case, there’s no reason for you to be alarmed or to wake them up prematurely.

Let your dog enjoy the dream and wait for them to wake up when they’re already well-rested.

Expressing contentment while asleep

In some instances, your dog will wag its tail while sleeping when they’re completely content. Whether they’re sleeping on their bed or in their favorite spot snuggled up beside you, their tail may wag start wagging unconsciously. You may notice your dog’s tail wagging slowly or just a few times before settling down again.

Experiencing cold or shivering

If you notice that your dog’s tail is wagging while your dog appears to shiver or shake, your dog might be cold. This can happen if the temperature drops quickly or you’re in an air-conditioned room. Make sure your dog is warm enough.

If your dog might be cold, cover them with a blanket or two to help them better regulate their temperature.

Having a nightmare

When you see a dog wag its tail while sleeping, which often is a sign of excitement or happiness, it could also mean the dog’s having a nightmare. 

Be cautious about waking them if your dog is barking, whining, or making sounds that typically indicate distress while slowly wagging its tail. 

However, if you’re going to wake your dog, heed a few reminders. Your dog might be confused or disoriented. Do not shake or touch your dog during a nightmare. Doing so risks the chance it might trigger the dog to bark.

Instead, gently whisper your dog’s name repeatedly until they slowly wake up from their bad dream.

Avoid shouting or talking to them with an anxious voice since this might startle them even more.

Once your dog is awake, give them a treat or hand them their favorite toy to help them calm down.

Having a seizure

In rare instances, seeing your dog wag its tail while sleeping can indicate a seizure. This can be tricky to spot because seizure movements can be similar to sleep motions.

You might notice your dog’s body goes rigid during a seizure. Seizures are frightening to witness, so it’s easy to feel panicked and afraid. But instead, stay calm because your dog might need assistance.

If your dog is seizing, try to support the head with a soft towel and keep them from falling if they are lying in an elevated space.

Avoid sticking your hand or putting anything else near their mouths during a seizure. That can cause your dog to bite you, or you risk creating a choking hazard.

Wait for the seizure to pass, and be there to keep your dog calm if they are disoriented.

If this is your first seizure, take your dog to the veterinarian as soon as possible. Your veterinarian may run a few tests to rule out possible conditions and find the underlying cause.

To prevent subsequent seizures, your vet may dog prescribe anti-seizure medications. If that happens, give the medicine to your dog religiously to avoid any recurrent events.

Tail wagging while sleeping may be normal until it’s not

When it comes to watching a dog wag its tail while sleeping, that may be a sign of many things, from happiness or contentment to excitement or fear.

During sleep, dogs may wag their tails as if they’re enjoying a good and exciting dream, or they may be wagging in anxiety if they’re suffering from a nightmare.

All of these situations are relatively easy to resolve as pet parents.

You can wake your dog from the bad dream calmly or let them enjoy their good sleep for a restful night.

However, it’s still best to stay vigilant about your pet’s movements even when they’re asleep, just to ensure your dog knows you’re there when they need your assistance or help.

Richard Thomas has been a freelance writer for animal and pet care for over a decade. He also is a volunteer dedicated to animal rescue and welfare, working for different organizations. He lives with two adopted cats and a rescue dog.