Sorry I didn't update sooner, I just wanted to keep monitoring Tia and making sure her condition was definitely stable before I posted this.

She seems better. Now, I'm not going to say miraculously better, because she is definitely not the rat she once was, but she's still trying her hardest to be Tia. I let her 'run' around my room each day just the same as always, although now it's more of an amble around my room. Yet, an amble is better than nothing. She still likes to sniff everything as she goes along, and shuffles over in my direction when I call her.

Her back legs aren't great. Her muscles in that area have vastly decreased in size and she can no longer get herself up to the next level in her cage. So, she just lives on the bottom part now. However, her cage is massive (it's intended to house about 4 rats), so it isn't like she's cramped or anything, and she gets at least 2 hours a day outside her cage. She sleeps a lot more than she used to, which is understandable, but she is still eating well and drinks pretty well too.

She's been on her medication and is taking it well, even though I think she's getting rather tired of having a syringe shoved in her mouth every day. She has two drops of Metacam on a treat as a painkiller and anti-inflammatory (for the mammary tumour, which is still walnut sized for the moment, and also may help with any pain she may experience in her legs) and 0.25ml of Baytril antibiotic to try and stem the tumour growth. I also give her 2-3ml of water in a syringe morning and night, just to make sure that she's definitely hydrated.

I'm still debating with myself whether she has a pituatary tumour or the paralysis is just due to old age. Sometimes I think the way she suddenly stops, stares and teeth chatters randomly are signs of senility, but then she doesn't seem to exhibit the posture associated with brain tumours. I won't rule it out, but I'm hoping that it's not the case and that the paralysis will be managable.

She isn't in the clear, but I think she's as good as she's going to get. I'll post some pics of her and the gerbils once I've posted this.

Thanks for all the thoughts and support.