Am i allowed to keep cats indoors?

I have two female cats. Both have been indoor cats since they were born. I am not sure if you've come across the indoor/outdoor cat debate, but basically it is safer to keep cats indoors for their own saftey i.e diseases,trafic accident,killing mice, being hurt etc. apparntly an outdoor cats life expectancy is 3/4 years compared to an indoor cats of 15 years. because i love my cats soo much and can;t bear to expose them to any hazadous situations i never let them out. thye have a very large space in the house to roam in. but i feel bad, koz im not sure if what i'm doing is wrong. because essentially they are wild animals and deseeve to be outdoors?

is there any islamic reaosning behind this? am i ok to keep them as indoor cats, or should i let them out? your reply will be much appreciated. jazakallah.