It’s an inevitability if you have an unspayed female cat: eventually, she will go into heat. When she does, it can be alarming if you don’t know what to expect. Her behavior and mood will change quite suddenly, and you may even wonder if something is wrong with her.
Understanding the signs and causes of your cat’s heat cycle is essential if you choose not to spay her. It’s a confusing and complicated process for both you and her, so the more you know, the better you’ll be able to comfort her (and ease your worries!)
Don’t know where to start? That’s all right; we’ve got you covered. Read on as we answer all of your burning questions about feline fertility, heat and the mating process – by the end, you’ll be prepared to handle your cat whether she’s in or out of heat.
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All About Fertility
What Is Heat?
The term “heat” refers to the period during which an unspayed female cat, or queen, is receptive to mating. When she’s not in heat, a female cat can’t get pregnant and thus is uninterested in mating with a male. The medical term for heat is estrus, and it’s just one part of the multi-stage estrus cycle that a queen experiences continuously throughout her life.
So, right up front, before we get into greater detail, let’s address the simplest question.
How Long Do Cats Stay in Heat?
If we add up the duration of each stage in the feline reproductive cycle, we can approximate that cats stay in heat on average between 3 and 4 weeks.
What Is the Estrus Cycle (Also Known As “Heat”)?
It’s not quite the same as a human menstrual cycle, but the feline estrus cycle is similar in that it’s a recurring fluctuation of hormones related to reproduction. The hormones have physical, emotional and behavioral effects that vary based on the stage of the cycle, much as they do in humans.
The exact sequence of the estrus cycle depends on whether or not a queen is mated with, and if so, whether or not she is impregnated. However, the cycle starts out with the same two stages each time: proestrus and estrus.
During proestrus, which lasts for just one or two days, the queen isn’t quite ready to mate yet, but she’s beginning to produce sexual pheromones – special scented hormones that are undetectable by human noses but irresistible to unneutered male cats. These pheromones communicate that she will be ready to mate imminently, drawing in suitors from far and wide in anticipation of the next stage: estrus.
Estrus is heat as we know it, and a queen in estrus can seem like an entirely different cat than normal. Her hormones are high, her pheromones are pumping out at full throttle, and her body is prepared to mate. For the next three to 16 days (usually around seven) she’ll have just one thing on her mind: finding and mating with whoever she deems worthy.
What happens next depends on whether or not she is successful in her quest to breed. There are three potential outcomes here, and to understand them, we first need to learn more about cat ovulation
What Is Ovulation?
Two types of cells are needed for a pregnancy to begin and a new life to form: a sperm cell, contributed by the male parent; and an egg cell, or ovum, from the female. An ovum originates in one of the female’s two ovaries, where sperm can’t reach it. For the two cells to meet and combine into one, the female needs to release the egg from her ovary; this is called ovulation.
In humans, ovulation occurs on its own, usually around once a month. Cats, however, don’t ovulate automatically. Rather, feline ovulation is triggered by the act of mating; this is called induced ovulation.
Mating stimulates the production of gonadotropin releasing hormone, or GnRH, which subsequently causes an increase in luteinizing hormone, or LH. Elevated LH levels persist for between 12 and 36 hours after mating and, if they reach a high enough concentration, result in ovulation. Often, one mating doesn’t raise LH enough to induce ovulation, so a cat may need to mate three or four times within a day or two in order to ovulate.
When the eggs are released from the ovaries, they leave behind the corpus luteum, a special structure that secretes progesterone and estradiol. These hormones are critical to sustaining a pregnancy, especially in the first few weeks, before the placenta begins to take over the sustenance of the embryos.
Once a cat begins to ovulate, her eggs begin to travel from her ovaries towards her uterus via the Fallopian tubes. Sperm cells survive for a day or two after mating; during this time, they can enter the Fallopian tubes and, if they’re lucky, meet up with the egg cells and fertilize them. Fertilized ova, or zygotes, immediately begin to develop and grow as they make their way down to the uterus, a journey that takes between seven and ten days.
What Happens After Estrus?
A cat’s estrus phase ends after ovulation occurs or if she didn’t ovulate, on its own after around seven days. Some cats are only in heat for three or four days, while others experience an estrus of over two weeks; every cat and every cycle is different. One of three phases comes next depending on whether a successful mating occurred.
If the queen was mated with enough to ovulate and her eggs were fertilized, she becomes pregnant. Pregnancy is considered to begin as soon as fertilization occurs and causes the estrus cycle to halt until shortly after she gives birth. For the next nine weeks or so, her womb will be home to between one and ten developing kittens; depending on how many different males mated with the mother-to-be, the litter may have multiple fathers.
Sometimes ovulation occurs but the eggs don’t get fertilized; this could be due to many factors, from an infertile male to genetic incompatibility to simply poor luck. When this happens, the corpus luteum remains active as if the cat were pregnant, albeit at lower levels of hormone production. This continues for around 40 days and is called pseudopregnancy, or diestrus.
During diestrus, the cat may show some early signs of pregnancy, such as enlarged nipples or an increased desire for affection. Usually, though, there are no visible symptoms of pseudopregnancy, other than the extended length of time that passes before the cat goes into heat again.
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Finally, if the queen was not mated with or did not ovulate, she will go into the phase of interestrus after her estrus phase ends. During interestrus, she won’t be interested in mating and will be back to normal both physically and mentally. The length of this phase is highly variable, ranging from just a few days up to three weeks, though on average it lasts between 10 and 14 days.
After the pregnancy is completed, diestrus finishes or interestrus ends, the cat returns to the proestrus state, beginning the cycle anew.
When Do Cats Begin Experiencing the Estrus Cycle?
Just as the human menstrual cycle becomes active at the onset of puberty, so too does the feline estrus cycle begin with puberty. In fact, for female cats, the estrus cycle is the most prominent indicator of puberty – the other symptoms we associate with puberty, like awkward growth spurts and acne, are mostly the territory of human teenagers.
Cats reach sexual maturity at a wide range of ages, though the average age is between six and eight months. The exact age at which feline puberty occurs is largely dependent on breed, though it’s also influenced by other genetics and even by the time of year they were born (see the section “Do Cats Have a Breeding Season?” for more information on this.)
Generally, short-haired breeds become sexually mature at a younger age than long-haired breeds. Siamese cats, in particular, are known for their early puberties, often experiencing their first estrus cycles at just four months of age. Persians, on the other hand, are rarely considered sexually mature any younger than twelve months old.
Another good rule of thumb is that larger breeds take longer to mature than smaller breeds. It’s not unheard of for Maine Coons, the largest domestic cat breed, to be eighteen months old before going into estrus for the first time. Your average mixed-breed cat, however, is half the size of a Maine Coon and takes a third of the time to hit puberty, usually doing so at around six or seven months of age.
Do Cats Stop Going Into Heat When They Get Old?
When human females reach a certain age, they stop experiencing the menstrual cycle and enter a period of menopause. During this time, hormone production drops, resulting in a cessation of functioning in the reproductive system. Cats don’t experience the menstrual cycle, so they don’t experience menopause, but do they go through a similar transition later in their lives?
The answer to this question is no; a cat’s estrus cycle is for life. Though other factors such as overall health and energy levels can impact an older cat’s fertility and behavior during estrus, the cycle continues all the same. Cats have been known to become pregnant well into their senior years, with some queens conceiving at the age of 15 years – that’s 76 human years, well beyond the typical age of menopause!
If your female cat isn’t spayed, she’ll keep going into heat for the rest of her life. As she ages, she may show greater levels of fatigue during heat, so it can sometimes seem like the cycle is tapering off. But she’s still able to get pregnant, and she’ll probably still attract plenty of attention from the neighborhood tomcats every few weeks as she enters estrus yet again.
Do Cats Have a Breeding Season?
We know that cats go into heat on an ongoing basis, with the cycle repeating itself every three weeks or so. But depending on where you live, your cat may spend several months out of the year in a state of anestrus, during which the estrus cycle pauses, and heat does not occur. The reason why has to do with light levels – and thus, with seasons.
A minimum of 10 to 12 hours of light per day is needed for a queen to maintain her estrus cycle. Without adequate light, her body will assume that it’s not a good time to reproduce – in nature, shorter photoperiods mean shorter days, shorter days mean colder weather and colder weather means less food. Queens exposed to fewer than eight hours of light a day experience an abrupt halt in their estrus cycle; around two weeks after returning to longer periods of light, the cycle resumes.
This means that in the fall and winter, usually from September to January in the northern hemisphere, cats may experience anestrus and won’t go into heat at all. Several factors impact this, including the exact location and pronouncement of the seasons as well as the breed of the queen and whether she’s allowed outdoors.
Seasons are more pronounced toward the poles and less so towards the equator. Cats who live further away from the equator are more likely to enter seasonal anestrus, as they experience the shorter days and colder climates that trigger the reproductive pause. Conversely, cats that live close to the equator experience more consistent photoperiods and temperatures, so anestrus usually isn’t triggered.
Long-haired breeds are far more likely to experience anestrus than short-haired breeds. The exact reason for this isn’t known, but it’s theorized that they’re genetically programmed to enter anestrus in preparation for the colder temperatures that their long fur is designed to protect them from. Regardless of their current geographical location, around 90% of long-haired cats experience seasonal anestrus, compared to under 40% of short-haired cats.
The source of light doesn’t seem to matter to cats when it comes to anestrus. Indoor cats who aren’t exposed to any natural light will still enter anestrus if their artificial lighting is reduced to under eight hours a day. However, cats who are allowed outside are more likely to respond to shortening photoperiods than their indoor counterparts, especially closer to the poles.
Overall, about 50% of queens experience seasonal anestrus while the other 50% experience a year-round estrus cycle. Even at higher latitudes, your queen may continue to go into heat throughout the winter, especially if she’s kept in a warm and well-lit home. But if she takes the winter off, don’t be alarmed – it’s perfectly normal.
All About Your Cat in Heat
What Are the Signs of Heat?
When your queen enters heat, you’ll know it even if you’ve never witnessed it before. It can seem like a complete personality change: even if she’s usually calm, relaxed, and well-behaved, your cat will transform into a needy, noisy, restless troublemaker when she enters estrus. The exact symptoms vary from cat to cat, but there are several common ones to look out for.
Cats don’t usually scream and yowl unless they’re in pain or in the middle of a fight. But queens in estrus don’t play by the rules. Their one goal is to mate, and if they have to get loud to do so, then so be it.
Those ear-splitting yowls may sound to us like the wails of death, but they’re music to a tom cat’s ears, and your queen knows it. Her screams get picked up by the sensitive ears of male cats from miles away. Upon hearing that there’s a mating opportunity, they can’t help themselves but follow the sound back to its originator.
When your queen is in heat, she’ll suddenly seem much needier than normal. She’ll rub obsessively on everything she sees, including you as if to beg for pettings and attention. She’s definitely in search of physical affection, but her rubbing has another purpose: doing so activates her pheromone glands and covers everything in her scent, which now carries the message that she’s ready to mate.
If you pet your queen while she’s in heat, you may notice that she reacts differently than usual, especially if you touch her hindquarters or back. She’ll lower her front half to the ground and raise her rump in the air, pushing her tail off to the side and treading with her back legs. This is the position she assumes during mating, and she reflexively gets into it when she’s pet on her super-sensitive spine and rear.
Estrus can cause a queen to lose her appetite and become restless, pacing back and forth and searching for opportunities to get outside. She can tell when males are nearby, and when she’s in heat, she’ll do anything to get to them. When she’s not looking out the windows and pawing at the glass, you’ll find her lying in wait near the front door, ready to make a run for it the next time someone opens it.
Spraying is the final symptom of estrus, and often the most bothersome one for us humans. Male cats are typically the ones who spray urine, but females in heat exhibit this behavior as well. We’ll explore why in the next section.
Why Do Cats in Heat Spray?
We discussed pheromones earlier – they’re the scented hormones that cats produce to communicate various things to each other, particularly their sexual availability. Cats secrete them every day by rubbing their faces, paws, sides, and tails on objects, humans and other animals, but the most powerful pheromones are excreted in urine. And since a cat in heat needs to send the most powerful possible message to attract the most mates, she often chooses spraying as her means of communication.
Anything can be a target for a queen’s urine spray, but she’ll probably aim for vertical surfaces and upholstered furniture – it’s easier for her to aim at vertical objects and fabric is more absorbent than other materials, so her scent will last longer. Curtains, sofas and hanging coats are all excellent choices in her mind, though once she’s out of those, anything will do, from the walls to the bookshelf to her unsuspecting owner’s legs.
Not all queens in heat spray urine, but many do; it’s an unfortunate reality of estrus, and it’s not something that can be prevented or reliably controlled. A cat in heat will do anything to attract mates, and the most effective way to do so is by spraying. The pheromones in her urine can be smelled from miles away and also communicate other information about her, such as her age and health – like a scent-based dating profile for felines.
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How Do You Help a Cat in Heat?
Unfortunately, there’s not much you can do to reduce the symptoms of estrus. The queen’s drive to reproduce is so strong that she’ll probably interpret any of your attempts to intervene as annoyances; that is if she even notices them at all.
Try to refrain from petting her back and rump, as these areas become very sensitive during estrus and stimulating them too much might result in your hand getting clawed or bitten. The head and neck are much safer targets for your affection, which she’ll probably be demanding in large quantities.
If your cat loses her appetite while she’s in heat, you may need to give her a more calorie-dense food, such as canned kitten food, so she gets enough nutrition. If she stops eating for too long, she can get severely ill; some studies suggest that kidney damage begins after just 48 hours without food. If her appetite is low, offer extra treats and try to encourage her to eat as much as she can handle.
Your queen will never feel the call of the wild as strongly as she does while she’s in heat. Cats are already quick, quiet, and crafty, but these qualities are especially true during estrus. She’ll rip holes in window screens and attempt to bolt out the door whenever it’s opened, but it’s much safer for her indoors.
Outside, your cat is always vulnerable to many dangers, but these increase dramatically when she’s in heat. The unknown males she encounters and mates with could transmit many diseases to her, and it’s not uncommon for an injury to result when everyone’s riled up from hormones. For your cat’s safety, keep her inside while she’s in heat.
How Do You Stop the Estrus Cycle?
The only way to permanently stop the estrus cycle, and thus the symptoms of heat, is to spay your cat. Spaying is a surgical procedure that involves the removal of the ovaries and uterus, sterilizing the cat. It sounds major, and it is, but it’s extremely safe and effective, with very few cats suffering complications from it.
The best time to spay your cat is before she goes through her first estrus cycle. Some vets will spay cats when they’re as young as eight weeks old, but many prefer to wait until the cat is three or four months old or reaches a weight of four pounds. Either way, early spaying prevents the onslaught of hormones that occurs when puberty hits, and thus the behavioral issues that are often associated with puberty.
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However, it’s never too late to spay your cat. Most vets prefer not to spay cats while they’re in heat as their reproductive organs are swollen during this time, and the risk of complications is higher. But there’s no upper age limit for spaying, and it has the same result no matter when it’s done: no more estrus cycle, and thus no more heat.
"In ancient times cats were worshipped as gods; they have not forgotten this."
-- Terry Pratchett