Cat walking on rocks in the garden.

Cat’s Accidental Mating (Mismating)

The question about what to do with the female cat that is accidentally bred is not an easy one to answer. In the old days, all that a pet owner needed to do was to take her in to the veterinarian for a “mismating” shot or pill.

What these treatments consisted of were formulations of the female hormone estrogen, which, if given within the first 36 hours after mating occurred, would effectively terminate a pregnancy. However, it is now known that significant side effects can occur if such drugs are used.

For starters, external sources of estrogens have been demonstrated to actually cause infertility in some female cats, rendering them unable to conceive at later dates. On a more serious note, estrogens can also cause a life-threatening anemia in sensitive cases.

And if that weren’t enough, they can also predispose a pet to pyometra after administration. To be safe, use of such estrogen-containing drugs is not an acceptable method for dealing with mismatings in cats.

So what are the options open to pet owners? To begin, valuable breeding females should be allowed to just go ahead and have the litter of puppies or kittens instead of chancing it with mismating medications.

If this is not acceptable, then either surgical removal of the fetuses from the uterus at a later stage of development or an actual ovariohysterectomy is warranted. Remember: All of this is assuming, of course, that a viable mating did indeed take place and that a pregnancy resulted from it!

Many mismatings do not result in pregnancy, and cause owners to grieve needlessly. Pregnancy detection tests are available through veterinarians and can be used to confirm whether a pet is indeed pregnant.