Rats sudden (aggressive) change in behavior

Question
Hi there,

We have a male rat that is about 7-8 months old, i believe. We have had him for about 3 months. Skittles has been the sweetest, most friendly pet and my boys and I just adore him. About 4 days ago, his behavior changed as if he were a different rat. He is skiddish and jumpy and when you go near the cage he jumps and hangs on the walls. He seems very agitated (sneezes and scratches more than usual). He bit my 8 year old last week and bit my 5 year old the other day and wouldn't let go. He won't let any of us pick him up. I even tried to keep the door open and let him come out on his own but as soon as I try to pick him up he strikes to bite. I put my shoulder at the door in hopes he would crawl on up but he bit my shirt. I feel so bad because we haven't held him for 3 days because he won't let us pick him up. I can assure that my boys are very sweet and loving to him so I know he hasn't been dropped or mistreated. I am wondering if he could be ill?

Answer
Yes he is either ill or in pain and needs a vet right away. It could be anything, from trouble breathing (causes severe agitation, panic etc...) or pain from something.  Males sometimes develop what is called a penis plug and this is caused by mucus clogging the opening and they cannot urinate right if at all. It will swell and turn red and the rat becomes agitated,  and may bite display anxious behavior if in pain.  This can be fatal if left untreated.  Any time a rats behavior changes like this, it is an indication something is wrong.  Your vet must really know about rat care and thats not easy to find one that knows what they are doing.  If you need a vet let me help locate one for you.