Can you keep mammary tumors from coming back?

Question
I have two female rats, both creeping up on 3 years old. They are both in wonderful health, but keep getting mammary tumors. Yoshi has had 2 removed, and now has 2 more. Lucy has had 6 removed, and now has another. It's getting kind of expensive to keep removing them, even though my vet charges me very little.

None are growing that fast, and Yoshi's seem to have "maxed out" on size. I don't want to simply let these tumors suck the life out of my girls, however.

I want to do the right thing and make sure I weigh all options.

I had a boy rat, Bob the Biter, who died because I thought he had a respiratory infection...and he probably had CHF. I couldn't find any info on the topic at the time. Of course, I find something on the 'net 2 weeks after he died. My vet wasn't schooled about rat care, but tried SO HARD to save him. I spent hours trying to find info that matched his symptoms. I wish I had found this site sooner.

Thanks for all the help you give everyone.

Answer
Hi Jim

I have been studying mammary tumors for several years, noting patterns of growth etc...
What I have found out during my research and also have my vets back up on this as well as the vets I work with is that these tumors start to show up (usually) around the time the rats estrus cycle ends, around 18 months and older.  When this occurs, estrogen levels go through the roof, fueling the growth of both mammary tumors and pituitary tumors as well.  As long as the rat produces high levels of estrogen, the tumors will continue to develop....sometimes no sooner is the rat healing from surgery and more pop up.  I have been through this many times with my own girls too and its heartbreaking. To prevent growth at all, the female rat should be spayed as young as 3 to 4 months old,and of course this means a SKILLED surgeon that is well versed on rats. This is invasive surgery and not as easy as a spaying a dog or cat.

However,spaying at any age may stop growth of new tumors but its still no real guarantee.  

Now the good news....that is, if you can get your vet to look into it.
A wonderful hormone drug, lupron, which is used widely in ferrets to help with their often fatal adrenal disease is also being used in rats with success.  It stops the production of estrogen, which as I said earlier, is what fuels the growth of these nasty pesky tumors. THe injection is once per month and should be used after surgery to try to halt new growth or slow down the growth of existing tumors.
I used it on my wonderful girl, Holly, who was well past 3, had her share of surgeries so we went ahead and used lupron. SHe lived to be just a few months shy of her 4th birthday passing away from old age but also organ failure due to the old tumors robbing her precious body of nutrients so she was unable to sustain healthy function of these organs...even though we removed them she had several more and we just didnt want her under that long. She was already under for 90 minutes which is amazing for an old gal like her. The tumors already started to take their toll on her body but she still had alot of spunk left and the lupron held the other tumors from getting bigger,while some even shrunk from grape size to pea size.  We were happy with the results. This is a human drug, btw.  
It works on benign tumors, which almost all mammary tumors are benign anyhow.

I am sorry about your little man rat having possibly CHF.  Often, CHF can mock lung disease and same for heart disease in general which often goes hand in hand with lung disease since the disease lung takes its toll on the heart as well.  CHF is common as is cardiomyopathy. The good news is (for future use) it can be treated with various drugs and the rat can live a productive life as long as the disease doesnt worsen as the rat ages, which is usually the case. The medication needs adjusted of course but as time goes, our rats eventually succumb to heart disease as well, it just doesnt have to be premature.
If you would like to perhaps find a vet that is more up to par with rats, I can find you one in your area, but sometimes its a drive. I drive about 40 minutes to my vet but its worth it. I got tired of having to tell the vet what to do for my rats and how to treat them, although that is part of the reason I got the position I have, but its still scary when you know more about rat care than the vet does.

I hope this helps some, and as you know, the more we educate ourselves on rat care the more we can help them since there just are not enough vets that are interested in taking a few more years of college to become an exotic vet.  Some vets say they will see rats and have a special interest in exotics but they still dont have the proper medication on hand or proper sized implements to treat them. You can even give a rat an IV if they are critical by using a 30 gage needle which most traditional vets dont have handy.
All I need is a zip code and I can do a search for a vet for you if you need one.

Keep me posted and feel free to write anytime. If your vet needs more info on lupron, let me know and I can help.

take care and good luck

Sandra