Behavior change in adult male rat

Question
QUESTION: A little over a year ago I adopted Andy from a shelter. The people from the shelter remember him being there for about 8 months but didn't know why he was put up for adoption.
The vet estimated him to be about a year old at that time, so he's almost 2 years old, if not older, now.

He's been an awesome rat, very sweet, though he'll bite you if you try to tickle him through the bars.  The people at the shelter gave him treats that way.

However, lately he's been getting overly excited when I let him run around.  He's pee marking and trying to hump my arm.  The first time or two. I told him no sternly and distracted him and that seemed to work.  But now he's starting to nip and scratch and won't listen or calm down, so I put him up.  After that he's seems his normal self.

I read another post where you suggested puberty, but is that possible in an older rat?  Plus, in the year that I've had him this is the first time he's started doing this.  Any suggestions?

Thanks for the help.

ANSWER: Hi Ann

Just a few things first so I can rule out a few things. Has anything been changed with Andy at all in the past few weeks or since you noticed a change in him?  New cage, loss or addition of cagemate or new animal in the room, did you paint the room or change or clean the carpeting?
Has his diet changed and in fact, what does his diet consist of?
Does he get an extra source of animal protein each week and do you avoid high protein and fats in his diet? Sometimes as the body changes, nutritional needs change and too much or too little of something can also change the personality of the rat too.
Illness, has he been sick recently and if yes, what was the diagnosis and treatment?

I have studied rat behavior closely for a long time and know that these changes can often be hormonal but not linked to puberty, but instead, sometimes an older rat can become a bit senile. I dont want to rule that yet of course and dont want to call him a senile old man just yet (he will bite me and it will be well deserved!) but its not unheard of.

Sometimes it is neurological...have you noticed any changes at all in his mobility?

Let me know these things I asked above so it will be easier to diagnose him once I understand better about his life style and habits etc...

hang in there!

Sandra


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

QUESTION: I noticed the change in him shortly my roommate, who I was very close with, moved out.  My roommate was always around and took care of him when I couldn't.  There have been a couple other changes in my life just before he started acting this way.

Nothing has changed in his room or cage.  He's a single rat,  he's never had a cagemate that I know of.  I don't think his  previous owners had any other rats either.  There have been no new animals in the house.  His routine has only changed slightly, meaning he's out of his cage for longer periods than before.  I don't work as much as I used to, so I've been able to let him roam around my room or watch tv in the living room more with me.  

His diet is Mazuri rat blocks, occasional yogurt drops and fruits, and he loves popcorn.  I try to avoid too much protein, since I've seen it cause a skin problem and eventual death in a friend's rat.  

He had a respiratory infection about 3 months ago, long before the change in his behavior, and it was treated with antibiotics and echinacea.

He has free roam of my room and always has.  Though,lately, he wants to sit as close to me as possible, and gets upset if I'm not cuddling him.  He's almost like a five year old kid.  Once he feels he's had enough cuddling, then he roams around for a little bit, but then hops back in his cage or comes back for more cuddling.  

The only other animals in the house are 2 cats that he's known about from the beginning, and I don't allow them to co-mingle.

Sorry if this is more info than you wanted.  What do you think?  Feel free to ask any other questions.

Thanks again.  

Answer
I think...he is missing your roomate. Rats attach themselves to the person they see the most and they do mourn their loss, they can even become depressed.

Rats thrive on repetition and his routine was changed when your roomate left and he no longer has the same routine he had before.

He will adjust to his new routine with you, but it may take a bit longer. Establish the same routine with him every day and he will feel more secure about it and will be content once his daily routine is once again concrete and he knows just what to expect. Take him out the same time each day or close to it, etc... This way he will be satisfied. Right now he is trying to establish his own routine and is getting upset it is not absolute everytime, which again, if you start a solid routine, he will be more calm about things.

However (dont you hate when HOWEVER gets tossed in?) If he gets worse and should start to seem like he is never satisfied with anything and begins walking around or even running like he is running to nowhere, this can be a neurological problem, possibly a tumor on the brain, which is not unheard of in older males, but right now I dont see that anxious behavior from what you are describing. Let me know right away if I missed that and he IS real anxious.

Hope this makes some sense!

Sandra