Heat in female cats: the reproductive cycle, ovulation, mating and reproductive disorders

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl

A cat in heat can surprise even an experienced guardian. Loud calling, rolling on the floor, rubbing against objects, raising her hindquarters and almost constantly seeking attention can make it seem as though something is wrong. Many people wonder whether she is in pain, how long it will last and how they can help.

Understanding the reproductive cycle is even more important for breeders. It helps explain when a female is ready to mate, why mating does not always result in pregnancy and why there may be gaps of several weeks between heats. It also helps distinguish normal reproductive behaviour from situations that need veterinary investigation.

A female cat’s cycle differs from a dog’s and is more complex than her behaviour alone might suggest. Not every heat ends in ovulation; ovulation can occur without mating; and raised progesterone does not automatically mean pregnancy. Understanding these relationships is fundamental to informed breeding decisions.

How can you recognise heat?

The signs are primarily behavioural. As oestrogen concentrations rise, the female communicates her reproductive readiness more actively. She may become unusually sociable, rub her head and body against people and furniture, roll on the floor and make characteristic, drawn-out calls.

One of the most typical behaviours is the lordosis posture: she lowers the front of her body, raises her hindquarters, treads with her back feet and moves her tail to one side. This is the natural posture that allows mating.

Some females become very restless, sleep less and lose interest in food. They may also urine-mark. Particularly intense or frequent heats can lead to noticeable weight loss and poorer body condition.

Not all females behave alike. One may call loudly almost around the clock; another may show little more than increased affection, rubbing and occasional adoption of the mating posture.

Is heat painful?

Heat itself is not a disease and should not cause severe pain. The characteristic calling does not mean she is suffering in the way an animal with a painful injury or inflammation would. It is primarily sexual communication.

That does not mean every female is unaffected. Intense arousal, reduced sleep and appetite, and being unable to express reproductive behaviour can cause clear discomfort and fatigue.

A female cat does not bleed during a normal heat. Any bleeding from the reproductive tract is abnormal and should not be attributed to heat. Pus-like or foul-smelling discharge also needs veterinary assessment because it may indicate reproductive disease.

How long does heat last, and how often does it recur?

Oestrus usually lasts about five to seven days, but there is considerable individual variation. In some cats the signs disappear after two or three days; in others they persist much longer.

If ovulation does not occur, heat is usually followed by a short quiet interval lasting about a week or slightly longer. Another heat may then begin. During the reproductive season, some females therefore show signs every two or three weeks.

It can appear as if the cat is almost continuously in heat. This does not always mean disease. It is important, however, to determine whether these are separate cycles with a return to normal behaviour between them, or one prolonged heat.

How can you help a cat in heat?

Provide calm, safe and predictable surroundings. Reduce additional stress, avoid unnecessary changes and let the cat decide whether she wants human contact.

Some females seek closeness, enjoy gentle stroking and settle in their guardian’s company. Others become more irritable and prefer a quiet place to rest. Offer play if she is interested, but do not force activity.

Take particular care to secure windows, balconies and doors. Even a cat that normally makes no attempt to leave home may actively seek an escape route when sexually aroused.

Do not punish calling, urine marking or other heat-related behaviours. She is not being spiteful and cannot consciously switch off hormonal responses.

Home methods such as mechanically stimulating the reproductive tract are not appropriate ways to stop heat. Giving hormonal medication or sedatives without veterinary advice is particularly dangerous.

For a female not intended for breeding, discuss neutering with a veterinarian. It permanently eliminates reproductive cycles and prevents unplanned pregnancies.

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl

When does the first heat occur?

The first heat most often occurs between six and twelve months, although individual variation is much wider. Some females mature at around four or five months; others do not show their first heat until after their first birthday.

Breed, genetics, body build and condition, birth date and environment all influence puberty. Reaching an appropriate degree of physical development also matters. Slender-built females may mature earlier than some large, late-maturing breeds.

Why does the time of birth matter?

Birth date can substantially influence age at first heat. Females born in spring and autumn reach developmental milestones under different day lengths, which affect hormonal activity.

A spring-born female may become physically mature enough in autumn, when days are shortening. Her first heat may then be delayed until the next breeding season, sometimes until she is nearly a year old.

A female born in late summer or autumn may reach the relevant developmental stage when daylight is increasing, encouraging reproductive activity. However, her first heat can also be substantially delayed.

Studies of cats living under natural light confirm an effect of birth month on puberty but do not establish one simple rule for all animals. Seasonal effects overlap with genetic differences, individual development and living conditions. Seasonality may be less pronounced indoors under artificial light.

Can other cats influence puberty?

The social environment may also matter. A sexually mature male or other females in heat can influence a young female’s reproductive activity and sometimes encourage earlier cycling.

Conversely, social stress, excessive competition and insecurity can affect behaviour and the expression of heat. A shy female, one subordinate to other cats or one living with group tension may show very subtle signs.

This does not mean a male’s presence always accelerates puberty, or that absent signs necessarily reflect stress. These factors should be considered alongside health, age and hormonal activity.

Sexual maturity does not mean readiness to breed

A four-month-old female being in heat does not mean her body is ready for pregnancy, birth and raising kittens. Sexual maturity can occur well before full physical maturity.

This creates a particular challenge for breeders. A female that starts cycling at four months may experience repeated heats for many months before reaching an appropriate age and condition for her first mating.

Our approach at Aggio Cat*PL

We do not arrange a first mating simply because heat has begun. We wait until the female is at least 12 months old, assess her development and health, and carry out the required tests, including echocardiography to screen for HCM.

If her first heat occurs at four months, we must responsibly manage recurring reproductive activity for the next eight months. That is not always easy, particularly when heats are frequent, prolonged or affecting her condition.

This is one reason breeding requires experience, appropriate facilities and cooperation with a veterinarian.

Why are heats seasonal?

The domestic female cat is seasonally polyoestrous. She can have several consecutive reproductive cycles during the breeding season, and their occurrence depends partly on day length.

Under natural conditions in the Northern Hemisphere, reproductive activity generally increases as days lengthen. Some females enter reproductive rest during the shorter days of autumn and winter.

Melatonin, produced by the pineal gland mainly in darkness, contributes substantially to this seasonality. As days lengthen, its secretion pattern changes, influencing the hormonal system controlling reproduction.

Seasonality can be less evident indoors. Artificial lighting and relatively stable surroundings allow some females to cycle throughout the year. Heat in December or January is therefore not necessarily abnormal.

What are the stages of the cycle?

The cycle includes several stages involving changes in ovarian activity, hormone concentrations and behaviour. Not every female experiences every stage in every cycle. Whether ovulation occurs is particularly important.

These durations are approximate. Publications give different ranges for the non-pregnant luteal phase, reflecting individual variation and whether they describe elevated progesterone, corpus luteum activity or the entire interval until the next heat.

The key distinction is that without ovulation a female usually returns to heat relatively quickly. If ovulation occurs, even without fertilisation, a luteal phase follows and may delay the next cycle by several weeks.

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl

How do hormones control heat and ovulation?

The hypothalamus, pituitary gland and ovaries work together to control the cycle. This system regulates follicular maturation, the onset of heat and preparation for possible pregnancy.

The hypothalamus releases gonadotrophin-releasing hormone (GnRH), stimulating the pituitary to release FSH and LH. Follicle-stimulating hormone (FSH) supports follicular maturation. Developing follicles produce oestrogens, primarily oestradiol, which cause the characteristic signs of heat.

Luteinising hormone (LH) plays a central role in triggering ovulation. After eggs are released, the remaining follicles become corpora lutea and begin producing progesterone.

Progesterone affects the uterine lining and prepares it for possible pregnancy. However, its concentration also rises when ovulation has occurred without fertilisation.

Why does uterine anatomy matter?

A cat’s uterus has a relatively short body and two long uterine horns in which embryos develop. Its inner lining, the endometrium, undergoes changes associated with the hormonal cycle and embryo implantation.

Oestrogen and progesterone influence endometrial thickness and gland activity. These changes are physiological, but prolonged or abnormal hormonal effects can contribute to uterine disease. Understanding this mechanism is particularly relevant to endometrial hyperplasia and pyometra.

Why does not every heat end in ovulation?

Female cats are traditionally classified as induced ovulators: egg release most often follows stimulation associated with mating.

Mating stimulates nerve endings in the reproductive tract. The resulting signal causes LH release, triggering final follicular maturation and ovulation. Ovulation generally follows within about one to two days of sufficient hormonal stimulation.

Repeated matings can increase the likelihood of ovulation by producing a stronger hormonal response. This does not mean every female must mate a particular number of times. Responses vary, and ovulation can occur after a single mating.

Without ovulation, follicles gradually regress, oestrogen falls and the female returns to interoestrus. Another heat may begin after a relatively short interval.

Heat does not necessarily stop immediately after mating. The behaviour can persist for a while and, by itself, does not establish that mating failed.

Spontaneous ovulation: can it occur without mating?

Yes. Although cats are primarily induced ovulators, research shows that some females also ovulate spontaneously, without mating.

This is particularly relevant to breeders because it helps explain long intervals between heats in females that have not been mated.

A 2024 study by Pereira and colleagues examined 29 intact females. Nine, approximately 31%, showed evidence of spontaneous ovulation. This was a small, specific group, so the result should not be treated as an exact prevalence for the entire female cat population.

Earlier studies also confirmed ovulation without mating, but their results varied considerably. The mechanisms are still not fully understood. Social and environmental stimuli are among the possible influences, but they do not allow prediction of whether an individual female will ovulate spontaneously.

Why does spontaneous ovulation matter?

Following ovulation, whether induced by mating or not, progesterone-producing corpora lutea develop. The female enters a luteal phase, usually temporarily suppressing another heat.

This also increases exposure to progesterone, which contributes to some uterine and mammary changes. Repeated luteal phases may favour progesterone-dependent disease, although spontaneous ovulation does not invariably cause complications.

If an unmated female has a gap of several weeks after heat, spontaneous ovulation is one possible explanation.

Are the luteal phase and false pregnancy the same?

Veterinary literature sometimes uses “pseudopregnancy” for the luteal phase following ovulation without fertilisation. The hormonal state should nevertheless be distinguished from clinical signs resembling pregnancy.

Not every female that ovulates without fertilisation behaves as though she is pregnant. Many show nothing obvious apart from a longer interval until the next heat.

Occasionally there is mammary enlargement, milk production, altered behaviour or increased interest in a nest. These are signs of clinically apparent false pregnancy, which is much less common in cats than in dogs.

Mammary enlargement or milk production should be discussed with a veterinarian to exclude actual pregnancy and other causes. Do not express milk yourself, because doing so may further stimulate lactation.

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl

What should a breeder know about planning a mating?

Recognising heat is only the beginning. Visible behaviour does not always correspond precisely to the point at which follicles are fully mature.

For many females, a favourable time is around the second to fourth day of heat. This is not a rigid rule. Observing her willingness to accept the male and understanding her individual cycle are more important.

Why do cats sometimes refuse to mate?

The reasons are not always medical. Cats are strongly attached to their territory, and moving them to unfamiliar surroundings can cause stress and inhibit sexual behaviour.

For outside matings, it is therefore often recommended that the female visits the male. He is usually more confident in his own territory. Some females nevertheless need time to become familiar with the new surroundings before accepting mating.

Both animals’ experience matters. A young, inexperienced or shy female may more readily accept a calm, experienced male; an inexperienced male may cope better with a previously mated female.

Never force mating or disregard clear stress or aggression. Even appropriately selected cats may not accept a particular partner.

What does normal mating look like?

The male generally approaches, grips the female’s neck with his teeth and mounts. She adopts lordosis, moves her tail aside and raises her hindquarters, allowing mating.

Copulation is brief. Afterwards, the female often vocalises sharply, turns towards the male, may strike at him, then rolls and licks her perineal area. This is characteristic but does not occur in every female.

The absence of a loud cry or rolling does not automatically mean mating was unsuccessful. Judging success solely by the female’s behaviour can lead to mistaken conclusions.

Breeders should record the dates and times of observed matings to help schedule examinations and estimate the expected birth date.

Is one mating enough?

It can be, but it does not guarantee ovulation. Both the intensity of stimulation and the individual hormonal response to LH matter.

Repeated matings during one heat increase the likelihood of ovulation. This is not a recommendation for unrestricted access to the female. Monitoring behaviour, fatigue and possible injuries is as important as reproductive success.

Can kittens in one litter have different fathers?

Yes. If a female mates with more than one fertile male during the same heat, different eggs can be fertilised by sperm from different males. This is called superfecundation.

It should not be confused with superfetation, fertilisation of further eggs after an existing pregnancy has begun. Superfetation has not been reliably confirmed in the domestic cat.

FIFe rules prohibit mating a female to a second male within three weeks of a previous mating. This supports reliable parentage records and responsible reproductive management.

Does successful mating mean pregnancy?

No. Observed copulation guarantees neither ovulation nor fertilisation. Failure may reflect absent ovulation, unsuitable timing, semen problems or disorders affecting the female.

Fertilisation may also occur without normal early embryo development. Embryos may die or be resorbed before pregnancy is recognised.

Infertility investigation should therefore involve more than simply repeating matings. The stage at which the problem arises must be identified.

How can ovulation after mating be checked?

Blood progesterone measurement is used in feline reproductive assessment. Testing around seven days after mating helps determine whether ovulation and formation of active corpora lutea have occurred.

This differs from the approach in dogs, where serial progesterone measurements are primarily used to identify the optimum mating time. In female cats, a post-mating test can establish whether stimulation led to ovulation.

Progesterone rises after ovulation. Diagnostic thresholds are used, but interpretation depends on sampling time, laboratory method and the cat’s clinical situation. An isolated result should not be assessed without the mating history and test timing.

Raised progesterone indicates corpus luteum activity but does not confirm pregnancy: it also rises after ovulation without fertilisation.

How early can ultrasound confirm pregnancy?

Pregnancy can be confirmed by ultrasound at around 18–21 days after mating. At this stage, gestational sacs may be visible as characteristic local enlargements of the uterine horns.

The exact timing depends on the actual ovulation date, ultrasound equipment and the examiner’s experience. An examination performed too early may be inconclusive; if necessary, it should be repeated after a few days.

Later examinations allow increasingly detailed assessment of embryo development and heart activity. Ultrasound therefore helps monitor the course of pregnancy and fetal viability, as well as confirm pregnancy.

Why keep a heat calendar?

Regularly recording the start and end of heat, the intensity of signs and intervals between cycles helps establish each female’s individual pattern. It can reveal changes that might be missed when looking at a single heat.

Record matings, progesterone results, confirmed pregnancies and any hormonal treatment too. These records are particularly useful when investigating infertility or recurring cycle disorders.

The aim is not for every female to have identical intervals. It is to understand what is typical for an individual and notice a clear change in her established pattern.

Silent heat: can it occur without obvious signs?

Not every female calls intensely or shows characteristic behaviour. Some have very subtle, almost imperceptible signs: this is known as silent heat.

It may occur during a young female’s first cycles but also affects adults and does not always indicate disease. Social conditions can play a role: a shy or subordinate cat, or one struggling within a group, may express less sexual behaviour.

If a breeding female does not show expected signs for an extended period, it is worth determining whether her ovaries are genuinely inactive. A veterinarian may use the history, clinical examination, ultrasound, vaginal cytology and appropriate hormone tests.

Vaginal cytology assesses oestrogen’s effects on epithelial cells. On its own, it confirms neither ovulation nor pregnancy.

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl

When is heat too prolonged?

Frequent recurring heats do not necessarily mean disease. If each is followed by even a short quiet interval before signs return, this can be the normal sequence of cycles without ovulation.

Continuous signs lasting several weeks are a different situation.

Uninterrupted heat signs for more than 21 days warrant investigation, including consideration of ovarian follicular cysts. This does not mean every female with signs lasting over three weeks has cysts. One persistent heat must be distinguished from several normal cycles.

Follicular cysts can continue producing oestrogen and cause prolonged heat behaviour. Some hormonally active ovarian tumours can produce similar signs, although they are much less common.

For suspected cycle disorders, a veterinarian may examine the ovaries and uterus by ultrasound and select appropriate hormone tests. Body condition, nutrition, previous treatment and the pattern of recent cycles also deserve assessment.

Why is a female not coming into heat?

Absent heat is not always abnormal. It can reflect seasonal reproductive rest, young age, pregnancy, lactation or a longer luteal phase following ovulation.

When a mature breeding female stops cycling for a prolonged period, other possibilities include chronic stress, inadequate nutrition, systemic disease, ovarian abnormalities and the effects of medication suppressing reproductive activity.

Reproduction demands substantial resources. Chronic undernutrition or an unbalanced diet can disturb cycling and fertility. Inadequate energy or protein and inappropriate amounts of particular nutrients may all matter.

Do not automatically give vitamin or hormonal preparations simply because a female is not showing heat. First establish the cause.

What else can cause fertility problems?

Infertility does not always result from failure to ovulate. Uterine disease, congenital abnormalities, hormonal disorders, infections and problems affecting the male are other possible causes.

One possible change is cystic endometrial hyperplasia (CEH), remodelling of the uterine lining associated partly with repeated exposure to sex hormones. Some affected females show no obvious signs, but reproduction may be impaired.

Another problem is accumulation of non-infected fluid or mucus in the uterus, known as hydrometra or mucometra. These may cause no obvious systemic illness but can be associated with impaired fertility. They should not be confused with pyometra, which involves infected, purulent uterine contents.

Less common causes include congenital reproductive-tract abnormalities, tumours and chromosomal disorders. These cases need individual investigation.

The male’s contribution must also be considered. Even a normally cycling female may fail to conceive if the male has semen problems, normal copulation does not occur, or mating does not trigger a sufficient hormonal response.

Can hormonal medication stop heat?

Breeders sometimes need to suppress reproductive activity temporarily. Mating at every heat is not always appropriate, and frequent cycles can leave some females intensely aroused and in poorer condition.

A very young female that has not yet had a litter and must remain out of breeding for several months can be particularly challenging. Repeated heats, prolonged signs and reproductive disease can create additional difficulties.

Veterinary medicine uses different methods of pharmaceutical reproductive control, including progestogens, melatonin-based approaches and GnRH analogues. These are not equivalent: they differ in how they work, how long their effects last, return to fertility and adverse-effect profiles.

Progestogens need particular caution because they can increase the risk of mammary gland overgrowth, glucose regulation disorders and uterine disease. Risk depends on the preparation, dose, duration and the cat’s health. Nevertheless, not all hormonal methods should be regarded as equally dangerous.

Some hormonal implants can act considerably longer than a breeder expects. Return to regular cycles varies between individuals and can be difficult to predict precisely. A method that seems convenient for a few months may therefore be unsuitable for a young female intended to breed at a particular time.

Responsible management in the cattery

At Aggio Cat*PL, we base first-mating decisions on maturity and health, not simply the onset of heat. We are also particularly cautious when considering pharmaceutical suppression in very young females.

Managing their heats requires patience, observation and appropriate organisation. If abnormalities arise or disease is suspected, we make treatment decisions together with a veterinarian.

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl

Can a female come into heat while nursing kittens?

Yes. Although lactation reduces reproductive activity in many females, it is not reliable protection against another heat. Some resume heat behaviour while still nursing.

The first heat may occur within two weeks of birth, and earlier cases have also been described. Other females do not resume reproductive activity until their kittens are weaned.

This can be a serious breeding challenge: lactational heat may be associated not only with changes in the mother’s behaviour but also with problems affecting her kittens.

Can the mother’s heat affect her kittens?

Associations have been described in scientific research.

Etienne Furthner’s 2023 publication examined lactational oestrus using breeder questionnaires. Among 195 births included in the main analysis, 96 involved heat while the kittens were being nursed.

In 37 of these 96 cases, breeders reported problems they associated with the heat, including reduced maternal interest in kittens, reduced milk supply and reported changes in milk characteristics. Kitten problems included poorer weight gain, diarrhoea, vomiting and other signs of deteriorating health.

These observations are important because gastrointestinal problems in newborns can quickly cause dehydration and weakness.

However, the study did not demonstrate that sex hormones passing into milk directly caused diarrhoea or vomiting. Changes in lactation, maternal behaviour and other health or environmental factors may also contribute. The research relied on breeder observations and did not establish the mechanism.

What should the breeder do?

If kittens develop softer stools, diarrhoea or vomiting while their nursing mother is in heat, treat this as a reason for particularly close observation. Do not automatically attribute the signs to her hormones.

Regular weighing and assessment of hydration, activity and feeding are fundamental, alongside observation of the mother. Check whether she remains willing to nurse and whether the milk supply appears adequate.

Diarrhoea and vomiting in newborn or very young kittens require urgent veterinary advice. Dehydration, hypothermia and hypoglycaemia can develop very quickly at this age.

Heat does not automatically make the milk unsuitable or mean that nursing must stop immediately. Not every lactational heat causes problems, but increased vigilance is necessary.

Can a nursing female be mated again?

Heat during nursing does not mean the mother is ready for another pregnancy.

Her body needs time to recover from pregnancy and birth, while lactation adds a substantial metabolic burden. Another mating must not be planned simply because heat has appeared.

Feline association rules also matter. FIFe rules allow a maximum of two litters in 12 months and three litters in 24 months. Exceptions require prior written approval from a veterinarian and/or the relevant FIFe member organisation, in accordance with the rules. Other federations also specify welfare and breeding-frequency requirements, although exact limits can differ.

These are organisational maximums, not a recommendation that every female should breed this frequently. Responsible breeding considers her individual condition and health, the previous pregnancy, birth and lactation, and her ability to recover fully.

Can pyometra follow heat even without mating?

Yes. Pyometra can develop in a female that has had no contact with a male. It is a serious uterine disease associated with bacterial infection and reproductive hormonal changes.

Progesterone is particularly important. It affects the uterine lining and may create conditions favourable to infection. Progesterone rises after ovulation, which in cats can occur spontaneously without mating.

This does not mean every unmated heat leads to pyometra. Without ovulation there is no typical progesterone-dominated luteal phase. Disease is therefore not an inevitable consequence of recurring heats: its development depends on multiple factors.

How does pyometra develop?

Sex hormones change the structure and activity of the uterine lining. Progesterone increases endometrial gland secretion, influences uterine muscular contractions and encourages closure of the cervix.

If bacteria enter the uterine cavity, conditions may favour their multiplication. Escherichia coli, which may also be present in the normal flora around the reproductive tract, is one of the most frequently isolated organisms.

Some females first develop cystic endometrial hyperplasia, which can favour infection. However, pyometra can occur without previously recognised CEH, including in relatively young females.

The disease may develop within several weeks of heat. Previous mating or pregnancy is not required.

Open-cervix pyometra

When the cervix is open, purulent discharge may drain through the reproductive tract. It may be yellowish, cream, greenish, brown or blood-stained.

It is not always easy to spot because females often lick the vulval area intensively. Discharge on bedding or unusually frequent perineal grooming may be the first clue.

Lethargy, loss of appetite, fever, increased thirst and more frequent urination may also occur. Early signs can be subtle.

Closed-cervix pyometra

Closed-cervix pyometra is particularly dangerous: the cervix remains closed and pus accumulates inside the uterus. There is no visible vulval discharge, which can delay recognition.

As pus accumulates, the uterus may enlarge considerably. The female becomes lethargic, stops eating and may vomit, drink more and urinate more frequently. Abdominal enlargement or pain sometimes occurs, but not all signs need to be present together.

Her condition can deteriorate very rapidly. Infection and bacterial toxins can cause circulatory problems, sepsis and a life-threatening emergency. Severe cases also carry a risk of damage to or rupture of the uterine wall.

How is pyometra diagnosed and treated?

Suspected pyometra always needs urgent veterinary assessment, whether discharge is visible or not.

Clinical examination, abdominal ultrasound and appropriate blood tests are central. Treatment depends on the female’s condition, the type of pyometra and breeding plans. In many cases, urgent removal of the ovaries and uterus is the safest option.

Medical treatment may be considered for selected, stable breeding females. It requires a veterinarian experienced in feline reproduction, close monitoring and acceptance of recurrence risk. It is not suitable for every patient.

Do not wait for vulval discharge: in closed-cervix pyometra it may never appear.

When is veterinary help needed?

Heat itself is physiological and does not need treatment. Consultation is necessary when signs suggest a cycle disorder or disease.

Continuous heat signs for several weeks, significant weight loss, marked weakness or an unusual change in the established cycle pattern warrant investigation.

Fever, a painful or enlarged abdomen, lack of appetite with lethargy, vomiting and abnormal reproductive discharge require urgent help. In particular, do not rule out pyometra simply because no vulval discharge is visible.

Frequent litter-tray visits, painful urination and straining are not typical signs of heat. They may indicate lower urinary tract disease.

If clear heat signs occur in a female that has already been neutered, remaining functional ovarian tissue is among the causes that need to be excluded.

Summary

Heat is a natural part of the female cat’s reproductive cycle, but its pattern varies considerably. One female returns to heat every couple of weeks, another has long intervals and a third shows such subtle signs that they are difficult to notice.

Age and breed are not the only influences on first heat. Birth season, daylight, body condition and environment also matter. Some females ovulate spontaneously, and raised progesterone does not automatically indicate pregnancy.

Understanding these mechanisms helps breeders plan responsibly, keep useful cycle records and recognise abnormalities promptly. Young females whose reproductive activity begins well before full physical maturity, and females showing heat during lactation, need particular attention.

Heat is not a disease, but not every behavioural change should be attributed to hormones. Careful observation, responsible breeding decisions and appropriate investigation remain central to protecting a female cat’s health.

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl

Sources and further reading

• Kijek K., Rozród kotów. Wprowadzenie [Feline reproduction: an introduction], Centrum Szkoleń Animalia training materials, 2020.
• Niżański W., Regulacja neurohormonalna i przebieg cyklu jajnikowego kotek. Patologia rozrodu [Neurohormonal regulation, the feline ovarian cycle and reproductive pathology], Wrocław University of Environmental and Life Sciences, Educatsja 2020.
• Niżański W., Monitorowanie przebiegu rui i ciąży kotek z uwzględnieniem biometrii płodowej [Monitoring feline oestrus and pregnancy, including fetal biometry], Wrocław University of Environmental and Life Sciences, Educatsja 2020.
• PawPeds, Normal Reproduction in the Female, Reproductive Disorders in the Female and Normal Pregnancy and Birth, training materials.
• Siemieniuch M., Fizjologia cyklu rujowego u samicy kota domowego [Physiology of the oestrous cycle in the domestic female cat], 2018.
• Johnson A.K., Normal feline reproduction: The queen, Journal of Feline Medicine and Surgery, 2022, 24(3), 204–211. DOI: 10.1177/1098612X221079706.
• Pereira M.C., Schrank M., Mollo A., Romagnoli S., Spontaneous ovulation in the cat: incidence among queens presented at a veterinary teaching facility, Journal of Feline Medicine and Surgery, 2024. DOI: 10.1177/1098612X241248351.
• Tsutsui T. et al., Breeding season in female cats acclimated under a natural photoperiod and interval until puberty, Journal of Veterinary Medical Science, 2004, 66(9), 1129–1132. DOI: 10.1292/jvms.66.1129.
• Furthner E., Prevalence of lactational oestrus in cats and consequences for kittens, Journal of Feline Medicine and Surgery, 2023. DOI: 10.1177/1098612X221141817.
• Romagnoli S. et al., WSAVA Guidelines for the Control of Reproduction in Dogs and Cats, Journal of Small Animal Practice, 2024.
• Hollinshead F., Krekeler N., Pyometra in the queen: To spay or not to spay?, Journal of Feline Medicine and Surgery, 2016. DOI: 10.1177/1098612X15623114.
• Fédération Internationale Féline (FIFe), Breeding & Registration Rules, section 3.3, version updated 1 July 2026.
• Merck Veterinary Manual, Reproductive Disorders of Female Cats and material on pyometra and hormonal reproductive control.
• Zambelli D. et al., Ultrasound aspects of fetal and extrafetal structures in pregnant cats, Journal of Feline Medicine and Surgery, 2002.

Agnieszka Mianowska · © Aggio Cat*PL

© Agnieszka Mianowska · Aggio Cat*PL · aggiocat.pl