Is it safe to let my indoor feral cat go outside and come back?

The main factors to think about are risk of injury (by cars and by other cats), risk of picking up disease (from other cats, intestinal parasites), and risk to wildlife (more of a concern if your cats like to catch songbirds) VS risk of increased stress due to being indoor only and risk of aggression between the two cats because they are stressed inside. From a behavioral perspective, being outside is much better. There is way more stimulation and it's a natural life for them. From a health perceptive, being inside is probably better, but we don't fully know the effects of the stress of being kept indoors. There are definitely ways to mitigate the risks of going outside, namely vaccination for Feline Leukemia and use of flea/tick preventatives, along with yearly fecal to check for intestinal worms. FIP, which is basically feline AIDS is not one that we vaccinate for and is transferred during cats fights, so they'd be open to that if outside. I hope that helps you think through your options! There's no perfect answer.

There is no fail safe way to make sure he will be completely safe as accidents can always happen, but personally I believe cats should be able to go out as it allows them to exhibit natural behaviour. Because he is an older neutered cat he is unlikely to stray too far, but obviously he hasnt had the experience of outdoors since he was young. I would start by taking him out on a harness, let him get used to your garden and outdoor sounds such as engines etc. When you come to let him off for the first time don't feed him before so he has a good reason to come home if he does venture off. Make sure he is microchipped and has an id on his collar just in case. To an extent you will just have to leave him to it, but he should be fine. Investing in a cat flap is a good idea too and make sure he is vaccinated. Good luck!

If he seems healthy now then the chance of survival is good. Although, there is always a chance he gets exposed to an infectious disease and/or trauma if he is outside, again. Make sure he is up to date on all vaccines, especially if he is going to be put outside again.

The main reason for letting your kitty out only during the day is that cats tend to be run over in the early hours of the morning when people rush to work, and coyotes tend to eat cats at night (other predators too. Feed your cat in the morning and at night, associate a call with the feed ("come Eat" or something similar) and that way she will come in when it is time.

Indoor cats typically have a safer and longer lifespan than thier outdoor counterparts. If she is happy indoors I would not encourage her to go outside. If you are able to build her a secure small "catio" cat porch outside that might be a way she can safely enjoy the outside. But cats that go outdoors are more at risk from trauma from vehicles or other animals and disease, parasites and viruses. I'd be happy that she is content inside.

Since she is blind I certainly think it is safest for her to stay indoors. Even though she has survived thus far outside, it is much more dangerous for a blind cat to be outside. Maybe you can let her out supervised occasionally since she does still want to go out.

Thanks for using Petco Pet Education Center, formerly Petcoach! The possible things that he could be exposed to outside include cat fights, cars, dogs, and possible infectious diseases that can be transmitted to him. I recommend that you have him completely vaccinated, neutered if he not yet and dewormed so that he is less likely to get infected and affected by anything. Good luck and have a great day!