This is actually not a great idea for your cat.
Firstly, your cat, if not sterilised, might contract sexually transmitted diseases such as the cat version of AIDS. If your cat is female, she might come home pregnant. If your cat is male, he might come back injured from fighting with other tom cats. (Whichever the case, please sterilise your cats at six months old.)
Secondly, your cat will run into other stray cats, and in a territorial war, get into cat-fights and get injured or stressed.
Thirdly, you cannot control what your cat eats outside and thus his health is compromised.
Fourthly, he might get fleas and ticks from grass and other cats.
Fifthly, neighbours might complain, and if the town council is contacted, usually the cat is caught to be brought to AVA to kill. Collar or not, there will not be any mercy.
Sixthly, your cat will be dirty and bring the dirt back to your house. If your house is dirty, you might also get complained against by neighbours and the whole complain-AVA-kill saga will begin.
There are many more reasons: your cat might get stolen by someone, get lost because he was chased or bullied by unkind humans, or was seeking shelter from rain. Or he might get knocked down by cars. Either way, you will lose your cat.
These abovementioned reasons are the main motivators as to why I made my first cat, Slinky, a totally indoor cat when she as a stray decided to adopt me. At first, I gave her outdoor access. She worried me when it was raining and I couldn't find her because she had hidden somewhere. She also vomitted out food that she had eaten outside. But after the time when I was hospitalised and Slinky couldn't find me when she came home, she seemed so lonely and had thought I had abandoned her. Upon the advice of my family and friends, I made Slinky a permanent house cat after I returned from hospital.
You may feel it is cruel for your cat to be confined indoors. This can be alleviated by the following:
- Get your cat plenty of toys and a scratching post
- Get your cat a cat condo to snooze on, play around and climb up on
- Make sure your cat has a proper litter tray to do his business
- Build an indoor cat garden so that your cat has some greenery to look at
- Get a cat harness and leash to bring your cat downstairs for a walk
- Get a pen to place outside your house for your cats' occasional use, so that your cats can watch the scenery but be protected in an enclosed space