I used to post here regularly, if you recognise me you know that I wouldn't be asking for opinions or advice on this lightly!
DH and I have rats and we've been known to take in the ones who have 'issues'. We had one, Ashi, who was a runt of a 17-strong litter, he was completely unable to stay with other rats, had epilepsy and was generally not a very well boy, but he was happy, had a lot of time out with us and was a lovely little thing until he had to be PTS for illness. We were told by vets from day one that we should "consider his quality of life" and we refused to consider putting him to sleep if he was happy and the seizures continued to not bother him, which they didn't.
We have another runt at the moment, Rygel, who we got last summer. He's got a lot of similar traits to Ashi but unlike Ashi he's happy with the others and would get depressed if we were to separate him. However, when he has his 'space out' type seizures, he gets incredibly defensive. The others learnt to avoid him during these and all was fine. However recently he's started getting extremely aggressive during these space outs and is targeting our smallest rat and we've had to remove him from the cage twice in the past two weeks now after he's attacked her.
Unlike with Ashi, Rygel has no warning signals of these types of seizures so we can't preemptively remove him from the cage before one. They last a few hours before he conks out and he wakes up happy and his usual self again the next day. The last two times that we've seen these space outs happening he has been targeting Kozu. When she manages to get away to a hammock that he can't reach he will stalk it and go straight for her if she leaves. He'll also fight the others if they go anywhere near him. DH managed to get him out of the cage last night and got a defensive bite for the effort. He said it is the first time he's ever actually felt scared of one of the rats and I have to say that I agree with him. We did manage to get him out using the towel method but given that this is the second time that Kozu has been injured in two weeks (and it would explain some injuries before that too which we weren't entirely sure about) we are having to seriously consider his quality of life and the effect he is having on the others.
This isn't a case of usual rat aggression, he's already neutered for a start and he's absolutely lovely and fun when he's not having a space out. He doesn't actively seek out the others company but he's happy sharing a space with them, seems to enjoy their company and is happy when they come cuddle with him. But right now he's in a cage on his own looking utterly miserable (he'll go back with the others when we're certain he's okay in a short while). Kozu has gotten quite reclusive and isn't spending as much time running around and the others have started avoiding him generally too.
I suppose that I'm just asking what others would do in this situation? We're certainly not new to owning 'difficult' rats or ones with health issues and we've never given up on any of them before. I do feel like we're giving up now though and I feel stuck. I'm going to speak to the vet about medicating him but I know that it can take time to sort out and I'm concerned that he may well end up seriously injuring Kozu or one of the others in the time it takes to work out what suits him.