cats being neutered and spayed

Question
My tenant has 2 cats, one male 1 year old and one female 7 mo. old.  I have been after her to get them fixed, but she is afraid to do it because she thinks it will change the cats behavior, etc.  I have given her articles on this procedure, but to no avail.  The female has already been in heat and she told me that the male did not bother with her at all.  I am afraid that this situation is going to get worse and I don't know what to do.  They are both totally indoor cats.  At the worse what could happen here?  Please advise on what I can do?

Answer
Hi Sue.  I never understand why pet owners think that getting thair animals fixed is going to harm them,when in reality they are harming them by not having the procedures done.  Getting a male neutered reduces testicular, penile and prostate cancers by 98%.  Getting a female spayed reduces her chance of developing mammary cancer, uteran cancer by 99%.  It also eliminates the chance of a female cat getting a deadly uteran infection called a Pyometra.  Getting them both fixed will also eliminate the amount of unwanted kittens in the shelters that are killed every day.
The male may not be trying anything yet....or that she knows of.  The next step will be that the female cat will get pregnant.  They WILL mate.  And the male will spray, making her home smell strongly of the ammonia-like scent of cat urine. The female may also urinate outside the litterbox while in heat.  You can use these factors to make her spay/neuter them, because I'm sure you don't want the space you are renting out to smell like the strong and stubborn odor of cat urine. She really needs to get them fixed.
I hope this helps and best of luck,
Hilary