is my rat sick?

Question
QUESTION: i have a pair of young male dumbo rats who are about 10 months old. today i noticed that one of them isn't acting his usual self. Normally he is the inquisitive one of the two and is always lively but today he's just quiet. I have let them both out on my bed to see if he was walking ok and he has just made a bed straight away and gone to sleep whilst his brother runs around. I have checked him all over for lumps (he had a fatty lump removed last year so I'm really paranoid)and cant find any but I'm not sure what else to do.

I have just noticed he has a slight blue tinge to his testicles so i checked all his paws to see if it was the circulation but they are fine and hes moving everything fine, hes still trying to wash and he was eating earlier.

He was fine last night as i checked him before i went to bed and had him out so now i don't know what to do

ANSWER:
Sometimes males testicles can have a slight blue tinge but its not always normal with every  rat.

I would take him in to have him checked just to be sure. Do you have a good vet?

---------- FOLLOW-UP ----------

QUESTION: i took him to the vet yesterday because the lethargy was worrying me, the vet said everything was fine and not to worry about his testicles but he thinks he may have a slight infection in his respritory system so he's on antibiotics to see if that clears it

Answer
Hmmm.....I do believe that if the vet is thinking the rat has a respiratory infection,  the testicles may have turned blue for a short time due to lack of oxygen from the respiratory infection. They dont always remain blue if the rat starts to breathe normally again. Cyanosis can be temporary.  The vet probably did not see any signs of cyanosis when he was there for a check up.  The vet should have known that chances were that they regained their natural color since you saw them when  he was cyanotic and of course having a respiratory infection will indeed cause this to happen.  Now I only hope the vet knows how to properly treat a respiratory infection, which should be for 4 to 6 weeks using baytril and doyccliine or zithromax and docycyline and also a penicillin based antibiotic such as amoxil. Penicillin is also a good idea to add to the mix to help with any  secondary infection.  What is rat on and can you tell and how many weeks will he be on it?