While you can mate two cats of the opposite sex by simply putting them in the same room together, this isn't the safest choice. Mating cats requires that each cat has grown to its full size and that you've checked them both for any genetic or health problems. Additionally, you need to catch the female cat when she's in her cycle. Approaching and executing the breeding process correctly both creates a more likely chance for pregnancy the first try and increases the likelihood of healthy kittens at pregnancy.
How to Mate Cats
Allow both cats to grow into their full size before mating. Breeding too early can stunt the female cat's growth, because she will put all of her energy into raising the kittens. Breeding the male cat too early can cause you to miss any genetic problems in his genes. Female cats should be somewhere between 18-24 months old before mating, while the male cat should be at least 18 months.
Schedule a veterinarian appointment for each cat before the mating process. Ask the veterinarian to give any necessary shots, perform a physical evaluation, stool sample check and any other necessary tests. Ensure that each cat is healthy enough to mate. The veterinarian should be able to tell you about any possible problems in mating the two cats or in the offspring they will produce.
Wait until the female cat is in heat. Outdoor cats are most likely to enter heat during the spring and summer. She will become extremely affectionate and attract any male cats in the immediate area for about three weeks. If she's not mated, she will leave the heat phase and enter again about two weeks later. Indoor cats can generally be mated year round because of the way artificial light affects their cycle.
Put the male and female cat into the same room. If the female cat is in heat, she will allow the male to approach her and mate. The mating process can take anywhere from 1-20 seconds. The male cat will run away, while the female cat will appear to thrash around after mating. This process is normal and can last up to 10 minutes. You can mate the female with another male cat in about 30 minutes, if desired. This increases the variety of offspring she is likely to produce.
Watch the female cat for pregnancy. The cat will be active for the term of the pregnancy, which is two months. You may see the nipples turn red and enlarge as early as day 18 of the pregnancy. If you're unsure if the female is pregnant or not, take her to the veterinarian and order an ultrasound.