Source: Daily News (Extract)
Posted: February 18, 2023

Spring and warmer weather are approaching, along with a very strong desire by animals to mate. As a result, animal intake in shelters and rescues increases at an overwhelming speed.  In our small shelter the puppy explosion is already beyond comprehension but now, with winter waning, cat breeding season has begun.

The difference is that dogs come into heat an average of 2 times throughout the year. Cats, however, are seasonally polyestrous, which means that they have multiple cycles during the breeding season, and that season will fluctuate according to geographic and environmental factors such as temperature and hours of daylight. The unsettling part is that it can begin as early as January, and end as late as December though, in the western hemisphere, March through October is generally considered the height of the season.

In outdoor cats, heat cycles occur seasonally because hormone production is stimulated by the light of longer days. Indoor cats who are exposed to long periods of artificial light may continue to go through heat cycles all year round.

The various stages of the cycle are called proestrus, estrus, interestrus, and, finally, anestrus. During proestrus the queen (an unspayed female cat) may begin to attract unneutered males (tomcats), but at this point, she isn’t interested in mating. This stage typically lasts a day or two, after which the queen enters estrus.  For about a week she may vocalize loudly, roll around, rub on things, and have a decreased appetite. Some queens will urinate more frequently or may even spray urine on objects (marking) when they are in heat. The urine contains both pheromones and hormones, both of which act as signals of her willingness to mate for those obliging males. The time between one estrus and the next is interestrus, a period of 2 to 19 days.  After that short interval, the cycle of proestrus, estrus, and interestrus will begin again, and continue throughout the season until the queen becomes pregnant or is spayed.  Anestrus is a very short reproductive dormant period of time occurring during the year.

Cats are induced ovulators, which means the act of mating stimulates the release of eggs from the ovaries. Most females require three to four matings within a 24-hour period for ovulation to occur. It only takes a minute or two for cats to mate, and cats may mate multiple times in a short period. Queens may mate with several different tomcats during this time, so it is quite possible that a litter of kittens may have several different fathers. Once ovulation has occurred, the queen will go out of heat within a day or two.  Pregnancy in the cat lasts an average of 63 days and, while they usually have an average of four kittens per litter, the range can be from one to 12 kittens.

You may have heard that cats cannot get pregnant as long as they are still nursing kittens. If that were only true, but unfortunately, it is not. One would think that getting pregnant again would be the last thing on her mind, but some cats, depending on their natural cycle, get pregnant a few weeks after giving birth. Nursing has no effect on her fertility or heat cycles, but getting pregnant so soon after giving birth is not an ideal situation. Adding the stress and demands of pregnancy on top of the stress and demands of nursing a newborn litter of kittens can definitely be detrimental to the cat’s health.

Unspayed cats have their first heat cycle when they reach puberty, which can be as young as 3 1/2 months of age. For those teenagers that get pregnant, their litters are particularly at risk since the moms are both still physically underdeveloped, and too inexperienced to successfully raise any kittens of their own. The mother’s own health can suffer from carrying a pregnancy while so young.

On average, a cat may live 13 or more years. It may become pregnant for the first time as early as four months old and possibly get pregnant every three months, having an average of four kittens per litter, with the probability that half will be female.  It is not rocket science.  If you can do some simple math, a single cat, during the course of a lifetime, can easily birth over 100 kittens. Unchecked, the numbers become astronomically higher, and exceedingly more difficult to deal with.