My bunny has enlaged uterus & and large lump in breast

Question
Hi Dr. Krempels

My bunny Daphne Rose is 6-1/2 yrs old.
I made a poor decision when I decided not to have her spayed.
Jan. of this yr. her vet discovered that her uterus was enlarged she did an x-ray and ultrasound, the vet was not positive, thought she might be in the early stages of cancer, the vet said she could go in and remove her uterus, but if it was cancer it could already have spread, If i did not want Daphne to have the surgery, bring her back for checkup every 6 mos. she had another checkup in June of this yr.  vet did not feel any tumors, which was grat news.
It is now Dec. and she had her 6 mos. checkup on sat. Vet thought she seem to be doing very well, her weight was the same, breathing normal, heart rate good, but discovered one of her little nipples is enlarged, she said it may be a cyst, but the only way to find out is through surgery.
Dr. Krempel do you think I should put my sweet little Daphne Rose through this. I feel deep down that she must have uteren and breast cancer now, if they open her up, the cancer will spread, the vet said she is still in good health, no signs of blood in her urine, but I wonder if I should just monitor her for another 3 months to see how her health is, or take the risk of sugery.
Her life expectantcy is 8-10, research shows that they can live with the cancer for 2yrs or so, she would be 8-1/2 by then, and lived a graet life. she full use of the house and no othet bunny could be loved more that I love her.
Some advice Please????

Answer
Dear Nannette,

This is a difficult situation.  There is no way to positively identify the masses in her uterus without removing them.  They could be fibroids, but uterine cancer is more common in rabbits.

The mass in her mammary gland also could be cystic (which is not uncommon in unspayed females because of hormones and constant false pregnancies), but it could be cancer.  Note that uterine cancer doesn't necessarily spread to the mammary tissues:  it more commonly metastasizes to the lungs.  So I would not assume that the uterus and mammary gland are both cancerous, or even from the same cancer founder cells.

This is a choice only you can make.  If she were my bunny, I would have blood work done to assess how likely she is to do well under anesthesia.  If she were a good risk, I would have the procedure done:  remove the swollen mammary gland and have the uterus and ovaries removed.  If her bloodwork suggests she's not a great risk, then your decision might be easier:  let her live with this, and hope it's not cancer.  (Cancer is not a nice way to die.)

I hope some of this is useful to you in helping you make a decision.

Good luck,

Dana