Rat gaining weight, not drinking much water, senses seems off

My two year old Cadence was always a bit of a chubby rat no matter how much she ran around, but in the last two weeks she's gained quite a bit of weight. Then when I can back from being away for the weekend not even half of the water bottle was empty when normally I have to refill this one every two days (she's got another water bottle on the upper level but she did not drink any from there). She is still drinking but only a little bit. Also, when I call her name she looks every where as if she can't figure out where the sound is coming from. Sometimes she barely responds to the normal attention getting noises. She can't seem to see or smell very well either. I was holding a blueberry right in front of her and she knew it was somewhere but kept looking everywhere but right where it was. I sat it in front of her and when she finally found it she kept dropping it and losing it even though it was right there. She normally snatches it up and hides in a corner to eat, gobbling whatever treat up till its gone.

Is everything just rapidly declining because of age? It strange to me that she's gaining weight, eating a lot of food, but is hardly drinking water.

I did notice a little pee, so she is not horribly dehydrated or anything. Though in contrast to the fact that she normally pees a lot, it worries me. Her poo is a lot smaller, a lot darker and looks shriveled.

She does have a hard tumor under her arm, could it be cancerous? She had a nasty, horrible, smelly, very large tumor on her leg that mysteriously shrank and is now tiny and fine. She also had two other fatty feeling lumps that disappeared. But this tumor is just there, it hasn't shrunk or grown much since it appeared.

Any suggestion on what might be wrong with my darling rattie, or how I can help her is appreciated.

Can you get a video of her for us? Especially eating a light treat or walking around with her feet exposed (not buried in blankets).

I would like to rule out PT (pituitary tumour) and there are some classic symptoms we would see during these behaviours.

I tried to get a video with my phone but it showed up to dark and she just looked like a pitch black rat shadow with pink ears... She just waddles when she walks and I'm pretty sure that's due to her weight. After giving her a small handful of blueberries (which took a while to locate) she seems a bit better and could find another blueberry better than before. I'm wondering if she was just dehydrated, causing her to feel off, and the blueberry juices helped a little? That doesn't explain why she's drinking so little in the first place, but I guess I'll keep a close eye on her and see if anything changes. I think I'll buy some apple sauce, she loves it and it'll help hydrate her.

Except for the weight gain, I would suspect a pituitary tumour. Perhaps she has more than one thing going on (tumour in her belly and a PT). I would put a bowl of water out for her just in case she is having a problem drinking from the bottle.

When she eats the blueberries, does she hold them with two hands? Does she sit normally? Do her hands sag/rest on the ground?

http://lilspazrats.wikispaces.com/Health+Care-+Pituitary+Tumour+-+Failing+the+Cheerio+Test (This was written by lilspaz, the rattie queen/expert who posted above )

I've been feeding her applesauce mixed with water, she doesn't seem to interested in water from a bowl. I think she's lost hearing in her left ear and her left paw does have trouble grasping things. It also looks like her right eye is going blind. I thought it weird that it was her right eye while the rest of the problems are on the left. Her condition hasn't changed since I last posted though, except I think she has mites now... would it be save to use Revolution with her in this state?

I think Revo is pretty safe. It's better to get rid of any parasitic infection so it's not contributing to the problem.

Okay, I'll have to get some as soon as possible then.