Cats are very efficient at reproducing and are able to have several litters a year with multiple kittens in each.  Most cats go through puberty at an early age—somewhere between five and nine months.  This is why it is so important to sterilize your cat at the time recommended by your veterinarian (typically 4-6 months of age).  Female cats can be fertile for about seven years, while males may be able to reproduce for eleven years or longer!

The large numbers of feral cats (cats that have returned to a wild existence) demonstrate that in an uncontrolled environment, cats will keep reproducing.  Today’s methods of feline sterilization are surgical and thus are not easily applied to the vast number of feral cats.  Researchers are working on new methods of feline contraception, including oral medications and even vaccines.  We look forward to new options to stop kitty overpopulation in the future.

Cats are seasonally polyestrus and are dependent on 12 or more hours of daylight to trigger their heat cycling.  Pubescent cats will repeat their heat cycles every two to three weeks until they are bred or induced to ovulate.  Female cats in heat do not bleed like dogs, instead they have changes in behavior.  The changes can include: increased vocalization, rolling on the ground and crying, lying on her belly with her rear end pushed up in the air, acting more affectionate, attempting to escape from the house and get outside, urinating outside the litter box or spraying on vertical surfaces.  If you have ever been around a cat in heat, she can be very annoying.

A couple of times a year, a client will call my clinic in a panic describing their female cat’s abnormal behavior and her wailing in pain.  They are worried that something is seriously wrong, but in fact she just wants to find a boyfriend.

If she’s in heat and given the opportunity to be with an intact male, chances are a female cat (queen) will get pregnant. The average queen is pregnant for 63 to 65 days. There are many physical changes a female cat will experience during a pregnancy

Cats do not need much special care to maintain a pregnancy. They do well on their own. Other than allowing a queen to eat what she wants and protecting her from illness and parasites, you can leave the rest to her.  Because cats are only pregnant for about nine weeks, things happen fairly quickly during pregnancy. The progression of signs is:

1. Increased appetite and weight gain

2. “Pinking up” of the nipples within two weeks of being bred

3. More rounded appearance of the abdomen

4. Engorgement of the mammary glands

A veterinarian can palpate a female cat’s abdomen and confirm a pregnancy three to four weeks into gestation. The fetuses develop more calcified bones at about 54 days of gestation, so an x-ray at this time can tell how many kittens will be born. An average litter contains three to five kittens, but in reality, litter size can vary a lot. X-rays do not damage the fetuses, and they can be useful if you want to know what to expect. Ultrasound is useful for confirming pregnancy as early as two to three weeks post breeding and for monitoring fetal heart beats, but it is not reliable for determining the number of fetuses.

You can expect that a pregnant queen is getting close to delivery time when she shows interest in creating a nest for her kittens. Milk will be present in her mammary glands a few days before she delivers. It is possible to monitor a queen’s rectal temperature twice daily if you are not sure when she will deliver. Twenty-four hours before delivery, the body temperature of most queens drops to about 99°F.

In my next column, I will discuss what happens during labor and what to do with new kittens.

Written by Dr. Wexler-Mitchell of The Cat Care Clinic in Orange, CA
Copyright © 2011 The Cat Care Clinic