I don't have any pets but in the family home decades ago, our three Cocker spaniels seemed to know when somebody wasn't well. Our eldest spaniel especially paid particular attention to the 'patient', making more of a fuss than usual and taking position by their side. Perhaps it's a dog's acute sense of smell or perception of unusual body language that gives them this apparent edge but I like to think it's a magical instinct that only they possess. Conversely, I don't recall our last cat ever noticing if someone was poorly. That's cats for you. More recently, I have noticed that the feral pigeons that perch on the roof opposite my front room always dive for cover whenever a thunderstorm is about to strike. You certainly notice when around fifty birds suddenly take to the air en masse and tear past your window. I wonder if they detect variations in magnetism in the atmosphere ? Following magnetic north is believed to be a method of navigation for the ferals' relatives, the homing pigeons.