Rat still lethargic weeks after illness

Question
About three weeks ago my 13 month old male rat suddenly became lethargic and started squeaking a little when he breathed. We found a patch of wet bedding in his cage (very unlike him) and assumed he had contracted a respiratory infection. We immediately started him on a course of tetracycline and the noisy breathing stopped the next day. He continued to loose weight for another day or two but then leveled out. We finished the two weeks on tetra and then kept him on a day or two more just to be on the safe side.

He's been off it now for 4 days but he still is very lethargic. He sleeps or lays in the same place with his eyes half-closed most of the day; only being active for about 10 minutes at a time 4 or 5 times a day. His breathing still seems a little heavy and fast but not labored or making any noise.

Even when he's awake his behavior is very different, he doesn't stash food anymore, he either eats when food is presented or ignores it completely. Also, he won't sleep in a nest box anymore preferring to sleep on top of the box with his head hanging off the edge. He's not getting any worse but he doesn't seem to be getting any better.

We've really babied him through this whole time letting him sleep on us when possible, hand-feeding him lots of tasty treats to try to get him to put weight back on, bringing the water bottle to him when we don't think he's getting enough water.

He's been a lone rat his entire life and we'd already started  started looking for a second rat to keep him company. Do you think a companion will improve his situation or is he still sick and needs more medical care?

Answer
Please read my website, sandyscrittercity.com and refer to the page on mycoplasmosis and properly treating it.

Tetracycline is not the right drug to destroy the mycoplasma organism which is 99.9% of the time the culprit in respiratory related illnesses.  The KEY to preventing relapse and chronic respiratory disease is to treat it properly in the first place.  This means using baytril and doxycycline together for 4 to 6 weeks straight.  Anything less and the rat will just relapse or regress back faster than normal. At this point, he could have anything from damaged lungs, such as lung scarring or blisters, or he may also have developed heart disease since this can occur as the  lungs. Collpased lung is also a reality.  The fact that he hangs his head over the shelves in the cage is an indication that he is unable to get oxygen properly and by putting pressure on his upper chest this helps him breathe better.  Please see my page on heart and lung disease as well.  You can compare your rat to the signs and symptoms on that page as well.

Is he breathig so hard his sides sink in?

Are his feet blue or purple tinged or very cold to the touch?

Try letting him lick baby food rather than having him chew as this can cause him to be short of breath and this is one reason why they stop eating. Chewing is tiring for them and hard to do it properly without getting out of breath.  Its much easier to lick. Baby food, stage one is best to use since it holds alot of water and if he isnt drinking, this will keep him hydrated.

Let me know after you read those suggested articles.  

I also advise he is given 7 days of gentocin.  If your vet is not willing to do this I would switch vets or you will lose your rat. It sounds like lung and heart disease, which is not shocking at all because of the lack of proper treatment from the first infection.  Not YOUR fault so do not blame yourself.  your not the vet.  

Where are you located?