Here's a partial list of what your cat misses by staying indoors. 

* Fights with other animals causing serious injury or rabies. 
* Attacks by other animals. 
* Infections from puncture wounds and scratches
* Fleas, ticks, and worms
* Being shot at, poisoned, or tortured
* Exposure to feline leukemia 
* Being stolen for reasons that often end in death 
* Being hit by a cat and killed or seriously injured
* Getting lost or trapped and turned into a shelter or relocated
* Getting caught in steel-jaw trap 
* Encounting sick or rabid raccoons and skunks 
* Encountering coyotes, large owls & other wild animals. 

Cats that spend time outdoors require more medical attention from injury and disease. the average life span of an indoor cat is about 15 years, It is less than half that for pets allowed to roam freely outdoors.