Once you ensure your kitty is safe inside your home all night and day, you will start to feel more secure. Your cat will likely benefit from the change, too. Cats who stay indoors have longer lifespans than those who are left to roam outdoors. In her article, Should You Let Your Cat Go Outdoors? Jacque Lynn Shultz from the ASPCA notes that indoor-only cats live an average of 10-12 years, while outdoor-only cats survive only an average of 2 years. This is because outdoor cats are more prone to being hit by a car; attacked by other animals; mistreated by humans; picking up parasites like fleas, ticks and worms; and contracting dangerous diseases like feline leukemia (FELV), feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP) and upper respiratory infections.