We all have heard stories about dogs having sixth sense or knowing it all before it actually happened or knowing the time of the day in relation to someone's arrival. Basically a dog's senses i.e. touch, smell, hearing,  sight and taste are finely tuned when compared to humans.
You all must have heard stories about dogs reaching in time to save their owner's lives or knowing it somehow that their lives were in danger. How does a dog gets to know about his owner's arrival and rushes up to the door just in time to greet him. How do they know beforehand if a person's going to die? Sure, can't be a coincidence each time. Studies over the years have revealed that dogs are intuitive in nature.
Time  It's not plain psychic ability that makes a dog know what time it is but his other senses too aid him in this work. Dogs are excellent with smells so they know the whereabouts of their human friends inside the house. But at the same time it is hard to explain how they mirculously appear out of nowhere when its time for their food or they want to go for a walk. Also, dogs have the ability of hearing a step before anyone else and immediately rush to greet the person concerned, it is the sound of the footsteps, they have incredible hearing power as well. Dogs do not have a clock like us humans, all they rely upon is the natural clock of night and the day and hence make out the time for every need.
Earthquake  There have been findings that changes in the behavior of dogs are seen before and after the earthquake, which is quite debatable but true to some extent. Also, dogs are known to flee the site where earthquake occurred in a day or two. What do we derive from it? Do we call it some sort of psychic ability or a play of strong senses? Whatever it is, it definitely is real and quite impressive.
Storm  Everyone of us must have observed the strange behaviour of dogs before the storm. They will suddenly start to bark non stop or be restless or running about and around. Dogs have the ability to smell rains before it even starts to rain or before the thinder strikes. The scientific  reason might be that dogs are more sensitive to barometric pressure than human beings and sense the approaching thunders beforehand.
Sensing Mood Dogs are the most sensitive creatures towards sensing anything put off. Dogs know when the humans are sad or angry and immediately try to console and distract them. They are aware of when a pregnant woman will go into the labor. They just know if any human around them is going to have a seizure anytie soon or has an impending serious disease, even cancer. Yes, they have the ability to detect all of the things said above and more. The secret of all this lies in their nose. Yes, quite literally in their nose. The reason behind this is a human being's internal chemical balance changes due to which they release a particular smell which enables the dogs to gauge the danger of it.
[Do Pets have a sixth sense?]
Hence the reason behind dog's psychic ability and sixth sense is the power that they all have. They have amazingly powerfull sensory organs which make them to be aid of the Investigative Agencies as well. It's the way God has built them. They are a man's best friend and the most loyal animal on earth. Lets cherish these loyal creatures and take care of them.