High-rise syndrome is the name given to the phenomenon of cats falling higher than two stories (7–9 m / 24–30 ft). This is generally from high-rise buildings, or skyscrapers, and is also used to refer to the injuries sustained by a cat falling from high up.
Studies done on cats that have fallen from 2 to 32 stories show that the overall survival rate is 90 percent. Strangely, cats who fall from less than 6 stories have greater injuries than cats who fall from higher than 6 stories. This is because cats reach terminal velocity after righting themselves (see below) at about 5 stories, and after this point they relax, leading to less severe injuries in cats who have fallen over 6 stories. Another possible explanation for this phenomenon is the fact that cats who die in falls are less likely to be brought to a veterinarian than injured cats, and thus many of the cats killed in falls from higher buildings are not reported in studies of the subject.
During a fall from a high place, a cat can reflexively twist its body and right itself using its acute sense of balance and flexibility. This is known as the cat's "righting reflex". It always rights itself in the same way, provided it has the time to do so, during a fall. The height required for this to occur in most cats (safely) is around 90 centimetres (3 ft). To achieve this, cats probably relax their ventral muscles, "flattening" their bodies to some extent and creating more resistance to air. Cats without a tail also have this ability, since a cat mostly moves its hind legs and relies on conservation of angular momentum to set up for landing, and the tail is in fact little used for this feat.