When you share your home with a dog, drooling is a fact of life. Some dog breeds are more prone to drooling than others, but it’s normal for all dogs to drool at some point. You may have even noticed a big wet spot on the bed where your dog’s head was after they got up from a long nap. 

Why do dogs drool in their sleep? 

Dogs may drool in their sleep for typical reasons, like being standard for their breed or dreaming of food. Sometimes dogs drool in their sleep for more complicated reasons, such as dental or gastrointestinal issues and foreign bodies. 

Before taking a closer look into some common reasons dogs may drool in their sleep, let’s learn a little more about why dogs drool. Drooling is one of the gross aspects of dog ownership that people put up with, but producing saliva is a normal bodily function that’s actually very beneficial.

Why Do Dogs Drool? 

Just like humans, dogs naturally produce saliva. While saliva in humans has enzymes to aid the digestive process by breaking down food, saliva in dogs serves a different function. For dogs, saliva aids the digestive process by keeping the mouth and esophagus moist so food can pass smoothly. When dogs have excessive saliva or drool, that’s called ptyalism. 

In addition to helping the digestive process, saliva promotes dental health too. Saliva contains minerals that help to protect tooth enamel and reduce inflammation. Studies show that saliva in dogs is even antibacterial to some degree. 

So even though we may think of drool or saliva as gross, it’s a part of a dog’s life that serves many purposes! 

Now that we understand how saliva is actually helpful for dogs, let’s take a deeper dive into some common reasons dogs drool in their sleep. 

Reason 1: Normal for the Breed

Since all dogs produce saliva, it’s normal that all dogs will drool occasionally. Some breeds are prone to frequent drooling due to their physical formation. Many giant breed dogs have large, saggy lips and jowls.

While this makes for a cute, wrinkly appearance, these droopy jowls can’t contain drool. Bloodhounds, Mastiffs, Great Danes, Newfoundlands, and St. Bernards are all giant breed dogs known for being extra drooly. However, many bully breeds like Rotties are also known to drool. When they’re asleep, the saliva collects in the folds of the lips and then spills out.

If you’re interested in owning one of these breeds, you should expect drool to become a regular part of your life. These breeds will regularly need their mouths dried to prevent drool from getting all over. Many dog owners of these breeds always carry a towel to wipe the drool away. 

Reason 2: Food 

While the smell of food is likely to wake your dog up pretty quickly, this could be why your dog is drooling in his sleep before getting up. Your dog might also be a total chowhound who is dreaming of food. Just dreaming of food could cause your dog to drool in his sleep. 

Dogs have over 100 million sensory receptors in their nose, making dogs smell 1,000 to 10,000 times better than people. If you’re cooking something like bacon, it’s not uncommon for your dog to start drooling. 

Your dog may even drool if he hears you open a bag of chips! Ivan Pavlov was a great psychologist who conducted many experiments that helped us identify why animals behave the way they do. In one of his famous experiments, he turned on a clicking metronome right before giving food to the dogs.

After many trials, he noticed the dogs began to salivate when the metronome was turned on but before the food was introduced. The dogs had learned the clicking metronome predicted food. This association is called a conditioned response. 

This experiment explains why your dog may come running from another room when they hear you open a bag of treats in the kitchen! But your dog doesn’t have to be awake for the drooling response to occur and even a sleeping dog may drool when their nose picks up a snack from the other room. 

Reason 3: Deep Sleep

Have you ever been so relaxed and had such a deep sleep that you woke up to a drool spot on your pillow? While our dogs can’t tell us when they’ve had a particularly restful night, we can only assume some nights they do sleep deeper than others. When dogs sleep deeply, their muscles relax, and more drool may escape their mouth. 

Reason 4: Heat

Dogs don’t sweat the same way humans do since most of their sweat glands are on their footpads. To cool themselves down, they have to use other mechanisms, like panting. When they pant and breathe with their mouth open, this allows excess moisture to evaporate…but it can also cause excess drool too! 

If your dog starts drooling in his sleep, take note of the environment and whether it’s been hotter than usual. If your dog has been panting more to cool down, that excess moisture and drool may come out of their mouth while sleeping. This is especially important to pay attention to if your dog is drooling in their kennel or any other spot where they may not be able to easily find a cooler spot around the house (like the bathroom).

Reason 5: Dental Problems

Dogs have lots of bacteria in their mouth. As the bacteria multiply, it forms an invisible layer on the tooth called plaque. The plaque thickens and hardens onto the tooth’s surface, creating tartar. All of these bacteria can cause inflammation in the gums, called gingivitis. This infection can spread deeper into the tooth and bone, causing teeth to become loose and fall out. Studies show that over 80% of dogs over the age of 3 have dental disease.

If your dog is drooling due to dental problems, you’ll likely see the drool is either blood-tinged or has a reddish-brown color. Dental problems for dogs are painful, so your dog may paw at their face, have a reduced appetite, or have trouble chewing.

However, depending on how the dental disease is impacting your dog, it could lead to more drooling in certain sleep positions than you’d otherwise see during the day while they’re awake.

The best way to prevent dental problems in dogs is to brush their teeth regularly. Studies show that daily tooth brushing reduces plaque, tartar, and the severity of pre-existing gingivitis. Unfortunately, daily tooth brushing won’t transform your dog’s mouth if they already have severe dental problems. Contact your veterinarian to determine if your dog needs a professional dental cleaning. 

Reason 6: Growths

Dogs can get lumps and bumps inside their mouth and esophagus, especially as they age. One particular growth is called a salivary mucocele. A salivary mucocele is an accumulation of saliva leaked after an injury to a salivary gland. As time goes on and the condition worsens, your dog may drool even more due to increased saliva accumulation and inflammation. 

Oral growths may cause your dog to drool more in his sleep because they’re uncomfortable. There are three common tumors diagnosed in dogs: melanoma, squamous cell carcinoma, and fibrosarcomas. The good news is that over 25% of oral tumors diagnosed in dogs are benign. 

If your dog has oral growths, you may also notice swelling around the mouth or neck, pawing at the mouth, or inappetence. You may even be able to see the growth in the mouth or notice other signs like vomiting, diarrhea, or weight loss.

As with most of the other medical reasons, you’re likely to see drooling while your dog is asleep and awake if your dog is suffering from a growth. However, depending on your dog’s sleeping position and the location of the growth some dogs could drool more as a result.

Reason 7: Foreign Bodies

Anything stuck in your dog’s throat or mouth that may prevent them from swallowing normally may lead to excessive drooling. These foreign bodies could be anything from a piece of bone or a wooden stick lodged behind a tooth. There’s also the possibility that a foreign body could even get stuck underneath the tongue. 

When dogs initially chew on a foreign body, like a stick, they may get cuts, scratches, or sores. Even if your dog spits out the foreign body, so nothing is stuck in their mouth, these remaining injuries may also cause your dog to drool.  

Dogs with a foreign body inside their mouth will show other signs of discomfort, such as shaking their head or pawing at their face. Depending on the foreign body placement, it could increase drooling while your pup is asleep especially if it’s lodged in a certain part of their mouth. 

If you suspect your dog may have a foreign body in their mouth, the easiest way to tell is by opening the mouth to look. If you see a visible object, you should contact your veterinarian. While you may be able to remove it, some foreign bodies leave behind secondary injuries that are more difficult to see. If you remove a foreign body, be careful because you don’t want your dog to swallow it. If you’re ever unsure, it’s always a good idea to consult your veterinarian. 

Reason 8: Stomach Upset

It’s normal for dogs to drool when they’re nauseous, and any issue causing your dog’s stomach upset can lead to excess saliva and drooling. When dogs are about to vomit, they produce excess drool to protect their throat and mouth from the acidic stomach contents.  

Reason 9: Toxic Ingestion

One common side effect of a dog eating toxic items is excessive drooling. Many household items, like certain household cleaners and plants, are toxic to dogs. If your dog ingests something poisonous, there would likely be additional symptoms like shaking, nausea, diarrhea, and lethargy. 

If your dog has ingested something toxic and is sleeping due to lethargy, this may be a reason your dog is drooling his sleep. 

Why do puppies drool in their sleep?

Not only do older dogs drool in their sleep, but puppies may do so too! While puppies may also drool in their sleep for any of the reasons listed above, there are a couple of reasons that primarily only pertain to puppies. 

Reason 1: Teething

All puppies go through teething phases. When puppies are about 12 weeks old, their baby teeth begin to fall out. By 6 months old, all of their permanent adult teeth should come in. 

Just like in humans, teething is uncomfortable for puppies. They may begin chewing on anything they can get their mouths on to alleviate some pain. Because of the pain and constant chewing, your puppy may drool and slobber much more than usual during this phase. 

Reason 2: Motion Sickness

If you notice your puppy is drooling in their sleep while in the car, a possible cause is motion sickness. Motion sickness is common in dogs, and this causes them to get nauseous and drool excessively. The good news is that in these cases, your dog should stop drooling and feel better once the motion has stopped. Most puppies grow out of motion sickness by about 1 year old. 

Should You Worry About Your Dog Drooling In His Sleep?

In most cases, it’s normal if your dog occasionally drools in their sleep. However, if your dog is drooling in their sleep frequently, or if you are concerned about any of the more severe reasons listed above, you should consult your veterinarian. 

In some severe cases, if your dog is drooling large amounts in his sleep, it could be related to dental or gastrointestinal issues. It’s also possible that a growth could affect your dog’s ability to swallow normally and cause him to drool.

It’s worth noting that if your dog is drooling due to a severe medical concern, he will likely drool throughout the day or will be experiencing other symptoms. It’s wise to take a trip to the vet anytime you notice multiple symptoms.

Closing Thoughts

While cleaning up drool and slobber may be one of the less glamorous aspects of owning a dog, it’s a normal part of a dog’s life, and our dogs are worth it. 

There are many reasons your dog may be drooling in his sleep, but chances are he’s just sleeping soundly. 

Does your dog tend to drool a lot?