Feline developmental stages

Introduction

Cats sometimes behave in ways that owners may find difficult to understand and/or manage. Problems can occur at any stage of development, and these can have far-reaching effects for a kitten, especially when it comes to the role of being a household pet and part of the family; it is therefore essential to understand the different feline developmental periods in order to help kittens grow into great cats and become good companions. Behavior is determined by several factors, including the cat’s genetic predisposition, the genotype of the sire and dam, what the cat has learnt from past experiences (good, bad and neutral), as well as the environment in which it finds itself at any given time. Epigenetics also has a role to play.

Knowing what to do to help kittens grow into well-mannered cats is important, and it starts with the breeder. Deciding which queen to breed with which tom, and when, is just one aspect that affects what the future might hold. Understanding how to handle the queen before, during and after pregnancy, how to help build resilience in the kittens, and how to raise them before they go to their new home are just some of the things that need to be considered, and the veterinarian should be willing and able to advise on all these aspects. Just as importantly, the owners of a new kitten need to be educated about how best to look after its physical and mental health, as both factors are important if cats are to make good companions. Having realistic expectations of what a kitten can and should do at any given time helps create a strong bond between the cat and its care giver.

The development of a kitten from a totally dependent neonate with a limited ability to perceive and respond to stimuli, to an independent creature with a fully developed physiology that is able to care for itself, hunt, and interact with members of its own species — as well as other species — happens rapidly. Yet the process is complex and delicate, and it is affected by many factors. Several different developmental periods have been identified; these are the prenatal, neonatal, transitional, socialization, juvenile, adult and senior periods, and each has an influence on a cat’s behavior (Table 1). As the kitten grows, all the various body systems, including the musculoskeletal and neurological systems, as well as the psychological (emotional) side of things, must develop in the correct sequence if the kitten is to develop neurotypically (i.e., normally). Much focus has been given to the socialization period, as this is when kittens are weaned, may be re-homed, and may be neutered, so there are many stresses on the animal during a very sensitive period of development. However, it is not the only period that needs to be considered. It should also be noted that the development periods are not rigidly fixed and will vary with each individual kitten — and in addition, different authorities will sometimes use different time frames for each period.

Table 1. The different life stages of a cat and the approximate ages.

Prenatal period

The prenatal period, i.e., conception until birth, at typically 63 days, is more significant than may be realized in terms of a kitten’s future characteristics. The different phases in embryonic development, that starts with fertilization of an ovum and leads on to implantation in the lining of the uterus (roughly two weeks after fertilization) involve a tremendous amount of change. Since cats are multiparous, this process is repeated by multiple zygote-morulas, possibly from matings with different males. Once pregnancy is established, the uterine environment also has extensive effects on the future behavior and development of the individual kitten. Research has shown that Kittens from queens fed a low-protein diet during late gestation and throughout lactation have been found to be more emotional and to move and vocalize more frequently than kittens from queens fed a balanced and complete diet 1. These kittens also lost their balance more often and had poor social attachment and fewer interactions with the queen. In another study, when queens were restricted to half of their nutritional requirements, the kittens demonstrated growth deficits in some brain regions (e.g., cerebrum, cerebellum, and brain stem) 2. These areas initiate and co-ordinate movement and actions, and delays were apparent in many areas of development, including suckling, eye opening, crawling, posture, walking, running, playing, and climbing. However, much research on the impact of diet on epigenetics still needs to be done. The feline microbiome is also an area that is increasingly being investigated, and its effects on kitten development are, as yet, not fully understood.

Neonatal period

The neonatal period starts at birth and lasts until approximately two weeks of age, although some authors consider the period to only last about 7 days. However, as the queen initiates nursing and elimination (perineal stimulation being necessary for urination and defecation) during the first 2 weeks of life, it is likely that the neonatal period lasts up to this point. Good maternal behavior is essential for healthy kitten development (Figure 1); as kittens are born blind and practically deaf, with limited ability to move and regulate their body temperature, they are totally dependent on the mother for survival.

Eating and sleeping are the most significant activities for kittens at this stage, and they will spend (on average) about 4 hours a day suckling in the first week of life. As kittens are born with their eyes closed (although many visual reflexes, such as the blink reflex, may be present before birth 3) and with poor hearing, they are reliant on their sense of smell, touch and ability to detect warmth. As the neonatal kitten cannot regulate body temperature, the ability to detect a thermal gradient is important for survival, whilst teat location is done using their sense of smell. However, although kittens do not vocalize much, they will purr when suckling and cry in response to physical discomfort. As kittens are born neurologically immature, movement is limited at birth and their legs are not strong enough to support their bodyweight until about the second week of life. However, kittens are able to reposition themselves if they are rolled onto their back, as this righting ability develops before birth. 

Transitional period

During this period (2-3 weeks of age) rapid physical and behavioral changes occur, and the kittens develop a degree of independence from the queen. The kittens can crawl and walk, albeit awkwardly, and the eyes and ears are now functional. The deciduous teeth erupt, although kittens will usually not start to ingest solids until the end of the transitional period at earliest, but their sense of smell will be fully developed by 3 weeks of age.

Importantly, it has been reported that kittens who were separated from their mother and hand-raised from 2 weeks of age appeared to be more fearful and aggressive toward people and other cats 4,5,6. They were also more sensitive to novel stimuli, their ability to learn was poorer, and they had less social and parenting skills. These effects may be attenuated, at least in part, if kittens are hand-reared in a home with other neurotypical cats, so that they can learn by observation of other felines.

Socialization period

Socialization is strongly linked to the neurological and physical development of the kitten, but the process is not just confined to kittenhood, as it continues throughout a cat’s life. How a kitten is socialized can play a role in how it interacts to new individuals as an adult cat. The socialization period is thought to last from approximately 3 to about 7 weeks of age, although some authors suggest it could last until 9 weeks of age. This forms an important distinction from dogs, as the cat’s socialization period appears to end earlier, but as kitten social play peaks between 9-14 weeks of age, it has been suggested that this may not always be the case. The duration of this period is also thought to vary according to the individual, the breed and experiential factors. During this period the kitten becomes more independent, and this is also usually when it goes to its new home.

This stage is linked to the further development of various body systems. By the time the kitten is 4 weeks of age its hearing is fully functional (they can recognize the chirps of their mother when played recordings of her chirps and meows against the same sounds made by other cats 7), and depth perception is present, although visual acuity continues to improve until about 16 weeks of age. The air righting ability is equivalent to that of an adult cat by the time the kitten is 6 weeks of age, and by 7 weeks it can maintain body temperature as well as an adult cat. By 5-6 weeks of age the kitten has full voluntary control of elimination, and digging in loose soil, followed by covering of voided feces and urine, may begin. The gape (flehmen) response begins to appear around 5 weeks and is comparable to adults by 7 weeks of age.

Also by 6-7 weeks of age adult-like locomotion is present, and during this period play develops, with several types recognized (social, object and locomotory play). Social play starts around 4 weeks of age and peaks at around 9-14 weeks of age. Object and locomotory play start at 6 weeks of age and peak at around 16 weeks, with eye-paw coordination developing from around 6 weeks (Figure 2). After 14 weeks of age fearful play starts, and the kittens learn to play fight, with social fighting occuring. It is known that single kittens play more with objects and with their mothers compared with kittens in litters 8.

Kittens will be eating solid food at this point, and will usually eat what the queen eats if given the chance; taste preferences are also established during this period. The time of weaning has been shown to affect the behavior of kittens 9,10,11,12, with early weaned individuals (from 4 weeks of age) showing predatory behavior earlier than normal, while late-weaned kittens (from 9 weeks of age) have delayed onset of predatory behavior and are less likely to kill prey.

From around 3 weeks of age a queen will start to teach her kittens the rudiments of predation 13, and by the time the kitten is around 5 weeks old basic, independent, predatory behavior is seen. Kittens are incapable of learning to respond to purely visual cues until at least 1 month of age, but by around 6-8 weeks they begin to react to visual and olfactory threats as adult cats would do.

Fearful reactions to threatening stimuli may start to be displayed by 6 weeks of age. Individual differences in behavior begin during the second month of life, due to genetic influences and different early environments. Increased handling (mild stress) appears to speed development. The most receptive time for socializing kittens to humans and other species is between 2 and 9 weeks of age, and the more handling by people, the less likely it is that fear of humans will develop. It appears that if kittens are to become social pets, then it is important to have human contact prior to seven weeks of age to enable them to develop socially acceptable behaviors 14. Regular, gentle handling and very mild routine restraint (picking up and holding) of the kitten should therefore be practiced before 3 months of age, and this should preferably start as early as possible, even from shortly after birth (Figure 3). It is also important that the kitten is exposed to various novel stimuli in a non-threatening manner during this sensitive period of development 15. This is therefore the best time to start “kitten kindergarten” classes (Box 1). Most veterinary behaviorists now believe that kitten socialization classes (when properly taught) are beneficial, and this concept is included in the American Association of Feline Practitioners (AAFP) feline behavior guidelines 16.

Box 1. Pointers for a successful kitten kindergarten.

Juvenile period

The juvenile period is considered to start at around 9 weeks of age and to last until sexual maturity (which occurs between 4-10 months of age). Although the basic behavioral patterns do not change during this time, there are gradual improvements in motor skills and coordination, and the kittens become increasingly independent. This period is associated with the kittens becoming ready to disperse, and they also become fully independent for their food needs. Play and exploration of inanimate objects and locomotory play will have started to escalate by approximately 7 to 8 weeks of age, but will peak at approximately 18 weeks. Social play is most prevalent from about 4-14 weeks of age, and will begin to take on aspects of predation in the third month of life. Object play may be social or solitary and may consist of pawing, stalking, leaping, and biting of objects and securing them with the paws. This type of play obviously simulates a variety of aspects in the predatory sequence.

Adult period

The juvenile period is considered finished with the onset of puberty — when sexual reproduction is possible — and the start of the adult period, which continues until the end of life. Female kittens may show their first signs of estrus between 3.5 and 12 months of age, although more typically between 5 to 9 months, and various factors play a part. Oriental breeds are often sexually receptive in terms of age before other breeds, and earlier signs of estrus can be influenced by environmental factors such as being born in the early spring, exposure to mature tomcats, presence of other female cats in estrus, or periods of increasing light. However, it is also influenced by the cat’s bodyweight and the season of birth, and it may also vary depending on whether they are born in the northern or southern hemisphere. Female cats are seasonally polyestrous — so that during the breeding season several periods of sexual receptivity occur — and they are induced ovulators, i.e., they do not ovulate unless mated, so one queen may mate with several males during this time. The juvenile period for male kittens is finished when they start to produce viable sperm at around 8-12 months of age.

Sexual maturity is not equivalent to social maturity. This term refers to the development of adult social behavior and interactions with other cats, along with territorial defense behavior. It is believed to occur between 36 and 48 months of age, which is longer than dogs take to reach social maturity, as it is thought that cats have to sufficiently develop physically and mentally to cope in an adult society.

Finally, more attention is being paid recently to the “senior” period of a cat’s life. Although relatively little research has been conducted to date on the senior cat in relation to behavioral changes associated with aging, these are well recognized in practice. Several behavioral alterations have been recognized in the aging cat, and a cat’s mental ability appears to decline as it gets older, and many studies are now being conducted on feline cognition and cognitive decline in senior cats.

Personality

The way that an individual tends to display characteristic behavior patterns, thoughts and feelings is described as personality. The ability of a cat to socialize with humans appears to be due to its inherited personality (Figure 4). Some research has shown that there are genetically “friendly” (bold)) and genetically “unfriendly” (timid) characteristics, and this part of the personality is paternally influenced 17. Thus, some cats may never be very confident around humans, regardless of the amount of socialization they receive. However, as noted above, regular handling from birth until 7-9 weeks of age can increase the likelihood of a well-socialized cat, and even 15 minutes a day is thought to be beneficial, with this effect being more profound for timid kittens. Variability in feline personality has important implications as to how well an individual will satisfy its owner’s expectations for a relationship with their cat. Bold, noisy cats are not valued by everyone, whilst some owners find it hard to cope with a timid cat that is not friendly to people.

Conclusion

Understanding the feline developmental periods helps us to better understand their behavior and why they do what they do. This is important for several reasons, including the fact that it helps breeders select individuals who will produce cats that will make the best companions, and because it helps cement the bond between companion cats and their carers (and hence hopefully decrease the risk of relinquishment and euthanasia due to unwanted behaviors). Veterinarians can and must give owners the best possible advice about cats and how they develop, so that the kitten’s welfare is optimal; that way the future of cats as companions is secured.