The entire development of the embryo is a fascinating study with scientific names for each stage, but for brevity and better understanding, we'll concentrate here on the basics. The fertilization of an ovum (egg) involves several steps, each resulting in a new stage in the development of an embryo, which will eventually implant in the lining of the mother cat's uterus, which has formed a "cradle." This occurs roughly two weeks after fertilization.
Since cats are multiparous (capable o bearing more than one offspring during pregnancy), this process will be repeated simultaneously by multiple zygote-morulas (fertilized cell masses), possibly from matings with different male cats, or toms. Not all embryos will survive implantation - this is truly a case of "survival of the fittest."
The embryo continues to develop, with the more highly evolved cells of the cranium and thoracic regions developing early. The embryo floats within a fluid filled cradle of two sacs, the amnion, and the allantois. Amniotic fluid contains water, protein, sugar, salts, fat, and traces of urea. The allantoic fluid, is filled mainly with excretory products from the fetus.
The placenta, the source of attachment between the maternal and fetal bloodstreams, develops later. The placenta is the "highway" over which oxygen, nutrients, and fetal waste interchange
Finally, when all the organic structures have been formed, the embryo becomes the fetus, and the first trimester is completed.
From now until birth, the major activities will be development (the second trimester) and growth (the third trimester).
Care of the Cat During Pregnancy
If you are fostering a cat or have welcomed a stray pregnant queen into your home, you'll need to have a veterinary "well-check." It is important in the case of a stray, to have her tested for FeLV and FIV and to discuss the pros and cons of vaccination.
Assuming you have a healthy queen, the best care you can give her is a diet high in nutrients, along with plenty of fresh, clean water. During the final 20 or so days, she should be switched to a premium quality kitten food, and continued on it until after the kittens have been weaned. Feed small, frequent meals. Her abdomen is full of kittens, and she won't be able to eat much at any one time. She should also be kept indoors at all times.
Impending Birth of Kittens
As your queen nears her time for giving birth, she will exhibit a few signs that will give you clues to the impending arrival of kittens. The first stage of labor lasts from 12 to 24 hours, and may include the following "symptoms:"
She may start snooping around in closets and secluded areas for an appropriate place to bear her kittens. The time is ripe for you to prepare an area for her in a private place, with a box or basket lined with soft towels. She may decide instead to give birth on the cold, hard floor of your bathroom, but at least you have tried to accommodate her needs.
- Increased affection
She may suddenly become very loving, and want to be near you at all times. Don't be surprised though, if a previously affectionate cat becomes withdrawn and seeks solitude. Either personality change may be completely normal.
- Decreased Activity.
Queenie may decide she'd rather sleep most of the time. She may also lose interest in food.
- Milk Discharge from Nipples
Your cat's nipples will have become enlarged and pink about the third week of pregnancy; 24 hours or so before birth, she may show a milky discharge. This discharge may come even earlier in cats that have given birth several times.
- Drop in Temperature. The normal temperature in cats is between 100.4°F and 102.5° F. A dramatic drop in her rectal temperature is a sure indicator that birth is imminent
If you want to plan ahead a bit, be sure to read When will my cat's kittens be born?