tumor/dead rat

Question
hi. i don't even know where to begin with this story. i've had rats on and off for 10 years and they are some of my favorite companions.
we currently had 3, although as of a few minutes ago 2, rats.
about 3 days ago we noticed that our older rat had what looked like a tumor on his head behind his right eye.
2 days ago, my husband was rebuilding their cage and during that hour we had the rats in a container for about an hour and i sat next to them observing b/c they aren't usually allowed together due to their temperaments and b/c one is a female and we don't want to breed rats.
anyway, they were getting along well, cleaning each other and eating some snacks and i was eating and was not paying much attention for about 5 minutes and in that time one of the younger 2 bit the tumor-thing off the head of our old guy.
he didn't make a sound and acted like nothing had happened so we have just cleaned and dressed the wound for the past 2 days and he seems to be doing just fine. It never even bled or anything.
we don't know who ate the tumor, but everyone has been acting normal up through today until about 5 minutes ago when we were at the cage interacting and saw that sometime in the last few hours our female died!
She was fairly young, has been a very easy rat, healthy and curious and interactive, although we did suspect she may have some mild brain injury(when standing still she would sway her head back and forth and was like that when we adopted her). I can't think of any reason why she would have suddenly died like this other than b/c she was likely the one who ate the tumor-thing off our other rats head.
Any thoughts on this would be greatly appreciated. I'm not expecting a miracle or a diagnosis, just your thoughts.
Thank you very much,
Melanie

Answer

For starters I am really sorry for your loss. Sudden death is unfortunately common in rats, esp pet store rats.  I do want to go over something with you though, that will put your mind to rest thinking she had some form of brain damage because she swayed her head. This action is very common in rats, esp red or pink eyed rats. They sway their head from side to side in order to judge depth.
It is called parallax motion and it is used to determine relative and absolute distance in objects.

I copied this from my website for you:
To better explain it, motion parallax is simply a depth cue that results from the way the rat moves, which in this case, swaying his head from side to side.  As the rat moves, objects that are closer to the animal will move farther across his field of view than do objects that are in the distance. This in turn tells the rat how far an object is in the distance.
Please check out for more info and also a video with a rat swaying her head...it is adorable more than anything.  

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

I just wanted you to know she had nothing wrong with her brain.
As for her sudden death:
She probably had an aneurysm or heart attack. These are the two most common causes of death when there is no symptoms of illness involved. Even at her age, it is not unheard of. esp a rat from a breeder that was not properly bred for health.

I am also thinking nobody ate the tumor from your other rats head. It was more than likely an abscess that had burst from activity, probably when he was with the other rats.  If it had been bitten, there would have been some sort of activity and believe me it would hurt if a rat bit into another rats tumor. It sounds like an abscess esp the location and the fact there was still a hole to clean out etc...this is typical of an abscess to leave a crater or hole. THe fact it didnt bleed also tells me it was an abscess and not a tumor. The tumor would be vascular and would bleed and the abscess would just be full of pus that would be gone by the time you noticed it had burst open.

These are just educated guesses of course, but it makes sense all in all as to what happened.

Again I am sorry you lost her....its always hard when it happens suddenly. I have had this happen too and necropsy showed things such as a bad heart we never knew our rat had. usually from a birth defect since she was younger, or a blood clot that broke off and traveled to the lungs (pulmonary embolism) or even to the brain. The list goes on...so its really hard to say and be totally accurate without a necropsy.  Hang in there and hopefully this helps shed some light for you and also adds some closure too.