male rat tumor

Question
QUESTION: Hi, I have a male rat who will be 2 years old in either jan or feb 2009. He grew a large tumor on his chest which I had removed a few months ago. (he is neutered). It has grown back but this time it feels really hard, different from the tumors on my other rats. It's still pretty small (about the size of a dime, only spherical, of course) so I want to get it removed before it gets any bigger. Is there anything to do for male rats to keep tumors from coming back? I always thought that in male rats tumors usually don't return. Which brings me to my next question: is there a cut-off age for when you should no longer have surgery on your rat? since my guy is nearing 2 years I'm a little nervous but he popcorns all over the bed and runs all around my room so I think he'll be fine, but is there a general age that one shouldn't operate on after, say 2 years maybe?
Thank you!

ANSWER: Hi
How long has he had this newest growth?  Is there a pit in the center of it or a black scab or crater?  Also, usually tumors in males dont return unless they are attacking the mammary glands. This is not as common in males as it is in female rats. There is an 80% chance that an intact female rat will develop mammary tumors after menopause around 18 months of age and about a 15% chance that males will have recurring tumors. Usually they are benign. Did you have the last one biopsied? As for a cut off age...no, age is not a disease, its just a number. The risk is there more if the rat is unhealthy or has a weak immune system, kidney or liver problems and of course heart or lung disease all play a factor in risks of anesthesia. However, even a 1 year old rat may be more at risk than a 2.5 year old is.  I had my 3 year old female operated on twice with the second surgery she was under anesthesia for 90 minutes which is pretty long.  It also depends on the skill of the surgeon. What I dont recommend is repeated surgery, regardless of the age, and what I mean by that is having them undergo anesthesia every month or two for tumor surgery etc... due to stress. Stress will hinder the healing process and weaken the immune system.  The biggest risk for surgery also is bleeding and infection. This is when the skill of the surgeon is important. I have a 3.5 year old male rat here now that has a few odd growths on his body. I wont remove them for several reasons. One, he is not the healthiest rat. He has had chronic myco for at least the past 2 years, bumble foot on both feet and arthritis in his hind legs. He is also very easily stressed and high strung. He is touch and grumpy. I do not feel he is a candidate for surgery but he also doesnt have tumors that will claim his life. The lumps he have I believe are lipomas and they do not really need to be removed.

So to answer you about cut off age, as long as your rat is healthy, there is no reason to avoid surgery if it is to better his quality of life.

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

QUESTION: Thanks for writing back. He has had this new growth for 2-3 weeks. There is no crater or scab or anything like that. I found out he had his last one removed sept 15. I was planning on having him have this one removed this saturday, nov 15, because I want to catch it before it gets too big. I figure if we get it while it's still small it will be easier for him to recover. The last tumor he had started out small like this one and then began growing exponentially so it got really big really fast. This guy had a ton of surgeries in his life. Another rat bit off his finger and then it got infected, so they had to operate to clean it off. Then I had him neutered so he wouldn't keep harassing other rats and get another finger cut off. Then his neuter got infected and they had to knock him out to clean it up. Then he got another finger tip bitten so it was hanging by like, a thread, and they had to put him out to clean that out. Then he had the tumor in sept. All the other surgeries were before september. He has always done really great with the surgeries, he is extremely friendly and loves all the attention he gets at the dr (the vet I go to is open 24 hours, so there are techs that check on the animals that are there all night, and I usually leave him one night after surgery to make sure there are no complications. I wouldn't want something to happen to him while I was sleeping!). He has no history of myco or any other lung problems. He never sneezes and has no polyphorin. He often goes on outings with me and enjoys meeting new people. The vet I go to is a certified exotic dr. So I'm not worried about his surgery because his health seems great and he has never had a problem with the surgery before. The question now is, is it better to remove the tumor while it's small, even though it's only been 2 months since his last tumor, or is it better to wait longer, but the tumor will be bigger? I will probably have the vet have this one tested. Usually my rats lumps are soft, but this one feels really hard. It's moveable, like it's not attached to anything, but it is hard which I haven't seen yet in any of my other rats (I've probably had, hmm let's see 8 tumors removed from my girls so far and they've all felt really soft).

Answer
Its best to do it now, while its small.  You dont want it getting really vascular since that can create bleeding complications during surgery and sometimes they may be a bit invasive, wrapping themselves around certain muscles and sometimes even getting into the bones and joints leaving the vet no choice but to leave some of the tumor behind. I would do it while its small just like you plan. I am sure too that he will be just fine under anesthesia.  My 3 year old rat was under for 90 minutes once which is really long for an old rat, and she was  fine and woke right up when oxygen was administered.