shrinking older male rat

Question
Last January, our children, 5 and 7, wanted pets.  My husband had had rats as pets in his childhood and a neighbor (who has since moved out of state) was raising rats.  The neighbor gave us a male, who he said was somewhere between 2 and 2 1/2 years of age, and a female who was about two months--still not fully mature.  They've since produced many children, some we've kept and some sold.  A couple of months ago, the male rat--"Ratty Boy"--began to slow down.  Everyone says rats live about 3 years, but a TV show said that they often reach 4 years when kept as pets.  Either way, he's of advanced age and entitled to slow up a bit.  He's a very sweet, laid back kind of guy, anyway--he's only ever shown agitation when competing with another male for a female in season.  About the same time, "Angel" (the female) began to have some seepage out of her right eye.  She and one of the other males also had scratches from her refusal of their advances (she only mates with Ratty Boy from what we can tell).  We figured it was just an injury from the altercation.  We live in AZ, so the weather only recently got cold.  The rats began to gain weight and fur, except for Ratty Boy.  Angel's eye healed up for a few days, then began to seep again.  We treated her eye for a few days by flushing it with the sterile emergency eye wash I keep on hand in case the kids get sand in their eyes.  Then I noticed she would clean furiously after we cleaned her eye and the pressure of the rubbing seemed to increase the seepage, so we left her alone and it cleared up again.  Meanwhile, Ratty Boy (please bear with me, this all ties together and I wanted to give you the full story) not only failed to gain weight, but began to lose more weight and his fur began to thin out.  The big (about 6-8 square feet) cage that my husband built is in our shop outside.  We got a medium, store bought cage and brought Ratty Boy and Angel indoors.  We didn't feel that Angel needed to be inside, but she's Ratty Boy's favorite companion and we didn't want him to be lonely.  Despite the cozy cottage for two, tons of availabe food and water, Ratty Boy has continued to lose weight (he's now barely half the size he was in October) and begun to stumble if on an uneven surface (our laps, the couch).  He drinks plenty, but eats little, even when tempted with treats like peanut butter, cracker bits, and cheese.  My husband keeps saying, well he' old.  I keep asking 'Is this normal old age?'  I figued they'd just fall asleep and not wake up?  Also, Ratty Boy has developed a foul odor, like a cage that needs cleaning.  I tried bathing him, being very careful to keep him warm.  Once he was dry, I thoroughly cleaned the cage, even though it'd been cleaned the previous day.  Then I cleaned Angel, because she was taking on his smell  from cuddling.  Our hands and clothes take on the odor, too, when we handle him.  Two hours after all this, he reeked as bad as ever. It's really an offensive smell and sad for the poor guy who cleans himself every hour or so when awake.  The last two times he tried to clean his tummy, he fell over sideways!  I've never seen anything like it.  Just a month ago, when Angel was in season, Ratty Boy was chasing Smokey across the big cage and obviously vanquishing him from the competition.  This, despite Smokey being bigger than Ratty Boy, even before the weight loss.  Smokey was born in the spring. Today, I pulled Ratty Boy out to pet and noticed that both of his eyes had seepage like Angel's right eye has had off and on for a couple months.  So, now I'm wondering if all of these problems are symptoms of an illness?  If so, does Angel's eye indicate that she has it as well?  If so, why isn't she wasting away like poor Ratty Boy?  Can a vet offer a treatment or just put him down?  Please help!!  These two are my favorite of the bunch.  The bunch includes two other males, a female, a litter of two and a half month old "little ones", and a new litter of five pinkies. I don't know if that's relevant or not.  Thank you very much for your help!!! P.S. Angel appears pregnant.

Answer
I just lost my 3.5 year old rat last night to a stroke. He weighed close to 2 pounds.  Rats can live this long providing they are taken care of. However, bad breeding or inbreeding or breeding rats that you have no idea what kind of genetics they have or what their genes may carry, such as fatal disorders such as mega colon or cancers etc...all of this can cause rats to live short lives. However, with the internet and all the good advice and good websites out there about rat care, rats are living longer as we find out about proper diet and find vets that know how to care for rats when they are sick rather than just simply euthanize them. Tumors can be removed easily, respiratory disease can be under control with proper medication....so our rats have been able to gain another year added on to their too short life span.

I have to ask what your boys diet has been his entire life. This sounds like he has kidney disease and possibly is in kidney failure. The odor is probably from failure to rid his body of toxins. He may be also suffering from heart disease, usually when kidneys fail this can cause heart problems as well and this would explain the lack of coordination, weakness and falling over etc...
You need to feed him baby food and try to keep him hydrated. His diet needs to be low protein.
Check my site for proper diet. If rats are fed high protein, kidney disease would be a result.

http://www.freewebs.com/crittercity/ratsandahealthydiet.htm

I would seek an exotic vet for help if you are interested in keeping him going but please do not breed him any more. I doubt he can anyhow. If you need a vet, please let me know and I would be more than happy to give you names of people in your area to take a look at him. Its not too late to help him by making changes in his lifestyle and he can also be treated for heart disease since rats can take most human grade heart medications.

The seeping your seeing from the eyes, is it reddish brown?  
Check out this webpage of mine right away and see if this is what your seeing and read what it is:

http://www.freewebs.com/crittercity/bloodynoseandeyes.htm

Let me know if I am seeing this right or if I am way off. I dont mind being wrong, and trust me, I love being wrong, esp if I think something really critical is going on. I would rather be wrong and have your rat have something super simple to treat rather than be right about something like this and see him pass away soon, because it sounds like he doesnt have much time left. :(