Beyond Romanticism¡

Why does your pet ‘flirt’ if you don’t want to have puppies or kittens?

It is very common that, when observing certain behaviours during heat—insistent meowing, restlessness, receptive postures, even attempts to mount—many owners conclude that their dog or cat ‘needs to mate’ or ‘wants to be a mother’. This interpretation is understandable (we are human and tend to interpret behaviour in human terms), but it does not accurately describe what is happening in the animal’s body.

In domestic females, sexual behaviour does not arise from conscious desire, emotional deprivation, or “frustration” at not having offspring. Biology is what drives this behaviour. These behaviours are driven by cyclical hormonal changes that activate very ancient behavioural programmes, designed by evolution with a clear and simple goal: to facilitate reproduction.

From a physiological point of view, during oestrus there is a significant increase in the plasma concentration of oestradiol, a hormone directly related to the onset of receptive behaviour. Endocrinological studies in female dogs have shown that oestrogen levels can increase more than tenfold compared to the anoestrus phase, coinciding with the most obvious behavioural changes. In cats, repeated hormonal stimulation can cause multiple heat cycles in the same season, especially in domestic environments with artificial photoperiods.

To put it bluntly: it’s not “I want to be a mother”, it’s “my body has gone into reproduction mode”. Understanding this difference completely changes the way we interpret what is happening… and also how we manage it at home, without guilt or drama. For example, when a cat goes into heat and vocalises intensely, it is not advisable to “scold” her, as environmental stress has been shown to increase cortisol release, which can prolong or intensify behavioural manifestations. It usually works better to reduce stimuli, maintain stable routines and offer activities that allow this biological activation to be channelled. In dogs, increasing scent walks and decreasing cognitive demands during hormonal peaks is associated with a measurable reduction in restless behaviour.

The ‘engine’ of heat: domestic endocrinology

During the sexual cycle, complex changes occur in the hypothalamic-pituitary-ovarian axis, a neuroendocrine system that coordinates reproductive activity. Key hormones such as oestrogen and progesterone are involved in this process, as well as neuromodulators that directly influence behaviour.

Did you know that males do not go into heat but respond to the scent of females?

Unlike females, males do not experience their own oestrus cycle: their increases in arousal and marking respond to the pheromones emitted by females in heat. Common veterinary fact about reproductive behaviour.

👉 https://www.asis.vet/el-celo/ 

Oestrogens promote sexual receptivity, vocalisation and contact seeking. Progesterone, which predominates after ovulation, modifies both uterine physiology and the animal’s general state. Experimental studies have shown that progesterone has a modulating effect on the central nervous system, influencing stress tolerance and social behaviour.

In addition, oxytocin, a hormone related to attachment and social interaction, may increase during certain phases of the cycle, which explains why some females become more demanding or “clingy”. However, this does not imply an emotional need for motherhood, but rather a transient neuroendocrine response. In fact, when spayed females are compared with intact females, the former show more stable levels of affiliative behaviour throughout the year.

In clinical practice, this means that during oestrus, the threshold for arousal decreases. Behavioural studies have shown that bitches in oestrus are more distractible and less responsive to complex commands, without this reflecting a loss of learning. Therefore, reducing demands and maintaining simple routines during this phase is not only reasonable, but also improves coexistence and reduces conflicts.

Typical behaviours during heat: when it seems intentional… but is a biological reflex

When a female enters her fertile phase, her body emits chemical and behavioural signals and, at the same time, becomes more receptive to copulation. These behaviours, which are often interpreted as ‘intentional’, are actually hormone-mediated reflex responses.

Fun fact: in many species, the presence of other females can alter oestrus.

In rodents, classic studies on pheromone exposure show that the presence of pregnant females’ urine can lengthen the oestrus cycles of others. This highlights how environmental chemicals modify reproductive physiology. 

In female cats, lordosis is very common, accompanied by intense vocalisations. It has been observed that in unspayed cats living indoors, episodes of nocturnal vocalisation can recur every 2–3 weeks, and that the duration of oestrus can be prolonged for more than 7–10 days if ovulation does not occur. This repetitive pattern explains why many owners report exhaustion and disruption to the family’s sleep patterns.

In these cases, environmental management has a real impact: studies on environmental enrichment show that structured play followed by a small food intake can significantly reduce the duration of subsequent vocal activity by promoting the transition to rest states.

In bitches, oestrus is accompanied by a relatively short fertile phase, but with marked behavioural changes. An increase in escape attempts and interaction with males has been documented, which explains why a significant proportion of unwanted pregnancies occur during routine walks. In fact, European veterinary surveys estimate that more than 60% of accidental litters are the result of brief, unplanned escapes during oestrus.

Understanding that these behaviours are not conscious decisions allows for practical prevention measures: controlling environments, more supervised walks and reducing intense olfactory stimuli. It is not a question of ‘correcting’ the animal, but of protecting it from a context that amplifies a biological response.

Reproduction and biology: motherhood is not a ‘life project’

In animals, the reproductive impulse does not respond to a narrative desire or an emotional project. The female goes into heat when her body is ready for fertilisation. This does not imply that she “wants to be a mother” or that her well-being depends on having offspring.

In fact, comparative studies have shown that spayed females do not have a higher incidence of behavioural disorders attributable to “reproductive frustration”. On the contrary, the continuous repetition of hormonal cycles is associated with a higher risk of reproductive pathologies, such as cystic endometrial hyperplasia or pyometra. In intact bitches, the cumulative risk of pyometra can reach up to 25% before the age of 10, a figure that clearly illustrates the health impact of maintaining repeated cycles without reproduction.

From a behavioural point of view, recording the frequency and intensity of oestrus allows us to objectively assess its impact. When each cycle involves family insomnia, escape attempts or conflicts between animals, we are not dealing with a neutral phenomenon, but with a factor that reduces the quality of life of both the animal and its environment.

“It looks like anxiety,” but it isn’t: hormonal activation and behaviour

During oestrus, many females exhibit behaviours that are confused with anxiety. However, from an ethological point of view, these manifestations are better explained by an increase in physiological arousal and search behaviour.

The organism enters a state of sustained reproductive alertness, with increased motor and vocal activity. Behavioural studies have shown that this activation disappears steadily after sterilisation, while purely behavioural interventions, without modifying the hormonal axis, only achieve partial and transient effects.

Therefore, practical strategies such as redirecting behaviour towards scent activities or controlled play work better than direct correction. In female cats, the combination of environmental enrichment and hormonal control significantly reduces the frequency of persistent vocalisations. In female dogs, the decrease in behaviours associated with heat after sterilisation is one of the reasons most cited by guardians as the main improvement in post-surgical surveys.

Interrupting the cycle is not “taking something away”: it is reducing biological pressure

From a health perspective, sterilisation interrupts the hormonal cycle and drastically reduces behaviours associated with heat. It is not just about avoiding litters, but also about medical prevention and well-being.

The data is clear: sterilisation virtually eliminates the risk of pyometra and significantly reduces the incidence of mammary tumours when performed before the first heat. Behaviourally, more than 80% of guardians report a clear improvement in behavioural stability after the procedure, especially in cats with repetitive heat cycles.

It is important to emphasise that the decision is not just “yes or no”, but also when and how. An individualised veterinary assessment allows you to choose the optimal time and minimise risks. After surgery, maintaining calm routines and a controlled environment helps hormonal changes translate more quickly into behavioural stability.

Key idea for guardians with heart… and head ❤️🧠

Sexual behaviour is not a choice, it is a physiological response. There is no trauma from not reproducing. What does exist, when cycles are repeated, is constant hormonal pressure that can affect well-being.

Golden veterinary advice: keep a record of heat dates and symptoms.

Recording dates, durations and behaviours during each cycle allows your vet to personalise recommendations and decide on the best time for sterilisation or medical management. 

Understanding this allows you to make decisions based on data, health and prevention, without myths or guilt, and to support your pet with practical measures while deciding on the best approach.

Sources and recommended reading

Concannon P. Reproductive cycles of the domestic bitch. Biology of Reproduction. Detailed review of the oestrous cycle and its hormonal implications. https://academic.oup.com/biolreprod/article/84/3/465/2530132

Root Kustritz M.V. Clinical management of oestrus in the bitch and queen. Theriogenology. Clinical analysis of oestrus behaviour and management. https://www.sciencedirect.com/science/article/pii/S0093691X14000668

Johnston S.D., Root Kustritz M.V., Olson P.N. Canine and Feline Theriogenology. Saunders Elsevier. Classic reference on reproductive physiology and behaviour. https://www.elsevier.com/books/canine-and-feline-theriogenology/9780721686879

Jitpean S. et al. Incidence of pyometra in dogs. Acta Veterinaria Scandinavica. Epidemiological study on the cumulative risk of pyometra. https://actavetscand.biomedcentral.com/articles/10.1186/1751-0147-54-18

Howe L.M. Short-term results and complications of prepubertal gonadectomy. Journal of the American Veterinary Medical Association. Health and behavioural impact of sterilisation. https://avmajournals.avma.org/view/journals/javma/211/1/javma.1997.211.1.57.xml