It is a well known fact that some animals can sense changes that are undetectable to humans. Often, people suffering from severe epilepsy will have a dog as they will start to warn their owners of an imminent seizure. In one study, out of 60 dogs, 15% were able to consistently detect imminent seizures.
A cat called Oscar made headlines recently in America by successfully predicting the deaths of residents in a nursing home. He would curl up with the patients during their final hours and a total of 50 deaths were accurately predicted using his Psychic Mediums ability.
Other animals that have been used for help over years are canaries which were taken down into mine shafts well into the 20th century to help detect any signs of toxic gas build up. Snakes are thought to be able to predict disasters like tsunamis and earthquakes due to sensing atmospheric changes or earth vibrations. For centuries cows have been thought to predict when the rain is coming and will lie down in the fields prior to the downpour and ground hogs in America are thought to be even better predictors of the weather. On the 2nd Feb each year when they leave their burrows, whatever the weather is doing is a sign of how long winter will stay.
Domestic animals such as dogs and cats are often thought to have a sixth sense or a Psychic ability and will pick up on any ghostly happenings in a home, often barking when they hit a certain point in the house or refusing to go into a particular room.