The concept of a "sixth sense" generally refers to the idea that an animal has a natural and intuitive awareness of something unexplainable. This could be a feeling of something about to happen, or if you believe in the supernatural, detecting an otherworldly presence undetectable by the other 5 senses: sight, smell, taste, touch, and hearing.
Dogs sense things differently than us, so it's hard to determine if and when they experience a sixth sense beyond their normal senses. However, we can probably all agree that instinct is like a sixth sense and that this affects dogs more than it does humans on a day-to-day basis. Dogs tend to act quickly when their sixth sense kicks in. For example, when they have a gut feeling something isn’t right, they’re likely to bark or react in some way.
However, we're not quite sure where this sense or instinct really starts or ends or if it's just how they experience the world through their enhanced smell and hearing.
It’s best to observe the context in which your dog is staring. Try to read their body language and if it is something to be alarmed about. Watch and listen intently to see if any other clues arise. Also, evaluate whether your dog is potentially in pain. And if it happens repeatedly, we recommend contacting your veterinarian.
Animal behaviorists talk about how dogs can predict impending disasters such as earthquakes. Natural phenomena and barometric pressure have odors that are beyond the capacity of a human nose to smell. However, dogs can recognize the change in smell. They can also hear high-pitched noises that humans can’t pick up.
While there’s no scientific evidence that dogs can predict earthquakes, there’s plenty of anecdotal evidence that they act unusually from days to seconds before an earthquake happens. A possible explanation is related to an earthquake’s P wave. It travels out from the quake's source faster than the larger shear wave (or S wave), which shakes the ground perpendicular to it. Humans typically don’t notice the smaller P wave, which arrives seconds before the S wave. But dogs likely can due to their enhanced senses. Therefore, they begin reacting before we know what’s going on. Their actions, whether it be barking or anxiety, can be perceived as a sixth sense to humans.
However, we’ll likely never know what dogs are actually detecting without lots more research. Since they’ve been known to react days before the earthquake strikes, any number of things could cause their senses to kick into overdrive.