The Veterinary Psychiatry of Cats

By Jacqueline Ley

The Veterinary Psychiatry of Cats introduces veterinary behavioral medicine and veterinary psychiatry using the domestic cat as its model. This book combines the most up-to-date understanding of biology of this beloved, revered and often maligned species with learnings from the fields of normal and abnormal psychology. Written by a leading expert in feline behavior, this book begins by assessing “normal factors of feline behavior, from neuroanatomy, neuroendocrinology, cognitive and social abilities. Delving into psychiatry, it then discusses mental health disorders, hindered development, and trauma. Psychopharmacology, including medications and supplements, are also explained.

The Veterinary Psychiatry of Cats finishes with a comprehensive view of feline welfare management, how to treat cats humanely and how to house them responsibly given their behaviors. This is an ideal resource for feline behavioral specialists, veterinarians and domestic animal researchers and practitioners, including veterinary technicians, students and even feline owners.

• Examines and explains normal versus abnormal feline psychology and its effects on a cat’s behaviors
• Addresses signs of feline psychiatric disorders, diagnoses and treatments
• Discusses medications and supplements to prevent, curve or care for feline behavioral issues

• Language: English
• Publisher: Academic Press
• Release date: Jul 10, 2023
• ISBN: 9780323905428

Jacqueline Ley

Dr. Jacqueline Ley (BVSc Hons, FANZCVS Veterinary Behaviour, PhD, DECAWBM) is a registered specialist in veterinary behavioral medicine. She currently consults on domestic feline behavior for the Melbourne Veterinary Specialist Centre. Previously, she was a full-time veterinarian at several small animal practices in the Melbourne Metropolitan Area. Dr. Ley received her BSc in Veterinary Science from Melbourne University VIC and her PhD in Psychology from Monash University. She is the third Fellow of the Veterinary Behaviour Chapter of the Australian College of Veterinary Scienctist (ACVSc). Dr. Ley has published numerous journal articles on veterinary behavioral medicine, specifically on domestic cat species and their psychology.

Book preview

Chapter 1: Describing the cat

Abstract

To understand the behaviour of the domestic cat, it is necessary to let go of common knowledge and beliefs. Understanding why cats behave the way they do starts with understanding their biology, their senses and their development from birth throughout life. Domestication also changes a species and needs to be considered when thinking about the modern domestic cat

Keywords

Cat

What is a cat? On the surface, this seems like a simple, possibly silly, question. After all, we all know what cats are because they are part of our milieu. They are in our homes, in our streets, in our stories, nursery rhymes and art. They are small, furry, domestic pets with sharp claws and teeth and are known to be aloof and demanding of their humans. They were worshipped by Egyptians and have never forgotten it. Cats have staff, dogs have masters.

It is time to put aside our stereotypes and popular cultural ideas of cats and consider them seriously as interesting animal. If we are to use them as a model for understanding the psychological principles needed to diagnose, treat and manage mental health issues in animals, then understanding the cat from several scientific perspectives is essential. To be able to treat mental health disorders in cats and maximise their welfare, then we need to understand what we know about their biology, physiology, social behaviour and neurology.

First steps are to describe the cat from a biological and zoological viewpoint. Their evolutionary history has shaped their bodies and brains while modern selective breeding is adding further changes. Knowing how cats sense their environment and how they can communicate allows interpretation of their emotional state and motivations for their actions. Their development from embryo to independent adult is an interplay of genetics and environmental influences with milestones that indicate normal development.

So, to begin again. What is a cat?

Chapter 1.1: Biology

Abstract

The special senses of the domestic cat are adapted to locating small prey animals in low-light conditions. The feline characteristic appearance of large eyes with slit pupils, pointed and mobile ears and long facial whiskers along with well-developed proprioception allows cats to move confidently in complex environments and to locate food. Their sensitive nose and taste preference profile are adapted for a carnivorous diet.

Keywords

Auditory; Cat; Feline; Gape response; Olfaction; Proprioception; Taste preference; Vision; Vomeronasal organ; Whiskers

1.1.1. Predator and prey

The cat is a small mammal that hunts rodents, birds, reptiles, amphibians and fish. They also catch and consume invertebrates such as insects and spiders. Due to being a small predator, the cat is also at risk of predation from larger predators in environments where their habitats overlap.

The domestic cat is classified in the order carnivora, family Felidae, species Felis silvestris sub species catus. It is considered to be the only domesticated species in this family of species. The domestic cat is considered to be descended from the Near East (or African) wildcat Felis silvestris lybica (Driscoll et al., 2007; Yu et al., 2021).

Domestic cats show some sexual dimorphism with males being larger and heavier than females. One study recorded average weights for domestic cats as 4 kg for males and 3.39 kg for females (Hendriks, Moughan, & Tarttelin, 1997). However, many cats, especially the giant breeds, are heavier than this. Domestic cats stand about 23–25 cm tall and on average are about 46 cm long (excluding the tail).

The characteristics that define the family Felidae are all seen in the domestic cat; large, forward-facing eyes, prominent whiskers, sharp canine teeth with dentition for a carnivorous diet, upright, highly mobile ears and sharp, curved claws (Table 1.1.1 and Fig. 1.1.1).

1.1.2. Special senses

Understanding how cats experience their world through the special senses of vision, audition, olfaction, taste, touch and proprioception helps to understand their behaviours, communication and responses.

1.1.2.1. Vision

One of the most prominent features of cats is their large, forward-facing eyes. Forward-facing eyes give a large area of binocular overlap and allow accurate judgement of depth of field and distances. This allows cats to jump accurately and judge the movement of animals and toys. Visual acuity, that is ability to see details, is less developed in cats compared with humans. What a human can see clearly at 100 feet (30.5 m), a cat can see at 20 feet (6.1 m) (Ofri, 2014). They have considerable binocular overlap which allows them to accurately judge the depth of field. They are able to discern that two objects are 2 cm apart with both eyes compared to the objects being 10 cm apart with one eye when 75 cm from the objects (Mitchell, Kaye, & Timney, 1979). Cats are reactive to movement in their wider visual field (Land, 2015). They are able to move their eyes but tend to use head movements to allow for smooth tracking of moving objects (Land, 2015).

Figure 1.1.1  Picture of Cat Demonstrating the Special Senses.

Table 1.1.1

---

Adapted from Lamberski, 2015.

Cats see very well in scotopic or low-light conditions (Kang, Reem, Kaczmarowski, & Malpeli, 2009). They do this by having better light-collecting systems compared with humans. They have a higher percentage of rods, the cells of the retina that are sensitive to light and movement. In contrast, cats have lower percentages of cones, which allow the detection of colour, detail and slow movement (Steinberg, Reid, & Lacy, 1973). Like many animals, cats also have a tapetum lucidum. This reflective layer covers 50% of the fundus in the cat and at its centre is 15–20 cell layers thick which is thicker than a dog or ferret (Ollivier et al., 2004).

The question of what colours cats can see has been difficult to answer. Anatomically they have the ability to see long wave (blue light) and medium wave (green-yellow light). Then it gets hazy-pun intended. They appear to have a trichromatic cone system and can respond to infrared light (Douglas & Jeffery, 2014) but it appears that they do not respond to red light easily. Studies that tested cat vision using behavioural responses concluded that either the cats did not respond to red light (Clark & Clark, 2016), or they could be taught to respond but it took a long time to train acceptable responses (Daw & Pearlman, 1970).

It is likely that the ability to discern colours is less important for cats than the ability to detect movement. After all, mice do not ripen to show when they are ready to eat. Thus, cats have cones for red wave-length light but do not make use of them.

1.1.2.2. Hearing

The pricked ears of the domestic cat are instantly recognisable. Cat ears are large, upright, conical and are highly mobile. Cats are able to differentiate sounds between 4° and 7° apart in the lateral plane (Heffner & Heffner, 1988). Cats use the interaural time, the level difference of the sounds reaching each ear and the directional amplitude to localise the sound and orientate their head and ears towards it (Beitel, 1999; Heffner & Heffner, 1988). While mobile ears don't help with localising sound in the frontal area, it is thought the advantage of mobile pinnae is that is may improve localisation of laterally located sounds (Heffner & Heffner, 1988).

The range of sound that cats can hear is much wider than humans. Cats appear to have evolved the ability to hear at higher frequencies without losing the ability to hear well at lower frequencies (Heffner & Heffner, 1985). One paper compared the results of six studies of hearing in cats and reports that at 60 dB SPL (Sound Pressure Level), cats can hear sounds from 45 Hz to 65,000 Hz (Strain, 2017). To put this in perspective, at the same loudness (dB SPL), humans can hear sounds at 64Hz to 23,000 Hz and dogs can hear 67 Hz to 45,000 Hz. Ultrasound is considered to start at 20,000 Hz. As many rodents cats prey upon vocalise into the ultrasound (Anderson, 1954; Hoffmann, Musolf, & Penn, 2012), the ability to hear into the ultrasounds allows cats to localise prey by their ultrasonic calls.

1.1.2.3. Touch

Another physical characteristic of cats is their whiskers. These specialised hairs (vibrissae) are very different from the hairs of the coat. Vibrissae are longer and thicker than ordinary hair. They have large follicles that are highly innervated and have blood-filled sinus at their base. Each vibrissa is precisely represented in the sensory cortex (Ahl, 1986) and transmits vibrotactile information (Grant & Goss, 2021). The vibrissae are attached to striated muscle and nerves that are exquisitely sensitive to the displacement of the whisker by 5 Å (50 billionths of a metre) or pressure on the whisker as small as 0.5 g (Fitzgerald, 1940). The striated muscle attached to the follicle allows the vibrissae to be voluntarily moved.

The whiskers on the cat's upper lip area are arranged in rows and the upper rows move independently of the lower rows. Cats fold the whiskers back when relaxed and spread them when walking or showing interest in something. There is also a superciliary tuft above each eye and two tufts between the ear and the point of mandible known as genal tufts one and 2 (Ahl, 1986). Genal tuft one is dorsal to genal tuft 2. There are also vibrissae on the back of both carpi just dorsal to the accessory pad. It is thought that these tufts aid the cat in using its forelimbs for activities such as hunting.

The role of vibrissae is to help the cat identify where it is in relation to its environment. Whiskers allow cats to accurately feel in situations where they cannot see. The facial whiskers on the cheeks and above the eyes help with negotiating the environment in low light. The facial whiskers and whiskers on the front legs aid in the capture of prey. The facial whiskers also help protect the eyes-pressure on these whiskers causes a retraction of the ipsilateral of the eyeball (Ahl, 1986). As cats cannot see clearly close to their faces, facial whiskers help in eating. This is why cats may complain to their owners that the food bowl is empty when the food is still present around bowls edges. The cat cannot see the food and cannot feel it with their whiskers, although they can smell it.

The response of cats to touch and temperature varies across their bodies. Watching cats, it is easy to see that they enjoy basking near hot things. But cats do not react to mild heat increases on the furred parts of their bodies until the heat reaches noxious levels (Kenshalo, 1964). The skin of cat's face is more sensitive to changes in heat. Behaviour studies with cats showed that they will react to changes as small as a 0.2°C increase and a 0.5°C decrease in the temperature of the skin around the nasal area (Kenshalo, Duncan, & Weymark, 1967). This ability is possibly an advantage for locating prey. Cats have individual differences in their preferences regarding petting and handling. Some like very strong pressure, whereas others prefer a light touch.

1.1.2.4. Smell

Odour is very important for cats. Their olfactory system is functional at birth. Kittens use scent to find their dam's teats (Raihani, González, Arteaga, & Hudson, 2009), while adult cats use scent for communication (Feldman, 1994) and in locating prey (Hughes, Price, & Banks, 2010). If kittens or cats have upper respiratory tract problems, this can affect their ability to locate food (Kovach & Kling, 1967), toileting habits, exploration of their environment, social interactions and participation in courtship (Vitale Shreve & Udell, 2017).

Further evidence of the importance of scent for cats can be seen in the anatomical structures of the olfactory system. The size of the epithelium is considered an indication of the importance of olfaction for the animal. The cat nasal epithelium has been estimated to be 20 cm². This is compared with approximately 200 cm² for dogs and 2–4 cm² for people (LeMagnen, 1951). Innervation of the nasal epithelium is very dense and has a direct connection with the brain. The nerve cells connect directly with neurons in the olfactory area of the frontal lobes of the brain.

Cats also have a vomeronasal organ (VMO) and show a gape or flehmen response when analysing some scents. The VMO has been described as a way for scents to be tasted. It is located between the oral and nasal cavities with connections with both. The gape response may be performed after the cat has sniffed or even licked at a scent source. By wrinkling the upper lip and opening the mouth, the cat opens the ducts of the VMO, allowing the natural secretion there to carry scent particles into the VMO (Eccles, 1982). Cats gape rather than performing the classic flehmen response of the horses and cattle because cats cannot fully evert their upper lip due to the frenulum between the upper lip and upper jaw. The gape response is frequently seen when tomcats encounter urine from another cat. However, queens and neutered cats also exhibit this behaviour when investigating odours.

1.1.2.5. Taste

Trying to understand how another individual, much less a whole species, experiences taste is difficult. While researchers report that cats like umami flavours and do not like bitter flavours and are not really interested in sweet flavours, many pet cats develop individual preferences for foods not typically considered flavours that they should like. For example, individual cats may seek out bread, cake and fruits.

Cats have low numbers of taste receptors on their tongues compared with people, dogs and cattle (Pekel, Mülazımoğlu, & Acar, 2020). While they do not have many taste receptors, cats have a high number of odour receptors and a vomeronasal organ (VMO) that allows them to experience odours as flavours. Odour is very important for cats to accept food and they prefer a single odour over a mixture of smells (Hullár, Fekete, Andrásofszky, Szöcs, & Berkényi, 2001). This demonstrates that the exotic and mixed-flavoured manufactured foods are more appealing to humans than to cats.

Research has shown that cats prefer animal source fats and proteins over vegetable source protein, fat, sweetened food or water (Beauchamp, Maller, & Rogers, 1977). They are indifferent to sweet foods, whether sweetened with sugar or artificial sweeteners because they do not have a functioning sweet taste receptor (Li et al., 2006).

Bitterness is a flavour that cats do respond to, and they have at least seven functional receptors for this taste (Lei et al., 2015). It is not clear why they are able to experience bitterness as this is something seen more with herbivores than carnivores. However, this sensitivity to bitterness causes problems for many cat owners as many medications are bitter (Thombre, 2004), making medicating cats difficult.

They also respond to amino acids, L-proline, L-cysteine, L-ornithine, t-lysine, L-histidine, and L-alanine, those that are considered sweet by people (Bradshaw, Goodwin, Legrand-Defrétin, & Nott, 1996).

Cats who hunt or have to find their own food show a preference for new foods if they have been eating the same diet for a period of time. This is considered to be a monotony effect, not so much a novelty effect as many cats will refuse novel foods. The monotony effect, selecting rarer food over food that has been eaten frequently (Bradshaw, 2006), is thought to help cats avoid a nutritionally incomplete diet.

1.1.2.6. Proprioception

Proprioception is the awareness of the position and movement of the whole body and body parts in relation to each other. This allows for coordinated locomotion and movements of limbs. The proprioception system co-ordinates information from sensory receptors in the muscles, skin and joints to identify the location of limbs and input from the vestibular system and the eyes to allow the animal to move in a co-ordinated manner.

References

1. Ahl A.S. The role of vibrissae in behavior: A status review. Veterinary Research Communications. 1986;10(1):245–268. doi: 10.1007/BF02213989.

2. Anderson J.W. The production of ultrasonic sounds by laboratory rats and other mammals. Science. 1954;119(3101):808–809. doi: 10.1126/science.119.3101.808.

3. Beauchamp G.K, Maller O, Rogers J.G. Flavor preferences in cats (Felis catus and Panthera sp.). Journal of Comparative & Physiological Psychology. 1977;91(5):1118–1127. doi: 10.1037/h0077380.

4. Beitel R.E. Acoustic pursuit of invisible moving targets by cats. Journal of the Acoustical Society of America. 1999;105(6):3449–3453 Retrieved from. http://link.aip.org/link/?JAS/105/3449/1.

5. Bradshaw J.W.S. The evolutionary basis for the feeding behavior of domestic dogs (Canis familiaris) and cats (Felis catus). Journal of Nutrition. 2006;136(7):1927S–1931S. doi: 10.1093/jn/136.7.1927S.

6. Bradshaw J.W.S, Goodwin D, Legrand-Defrétin V, Nott H.M.R. Food selection by the domestic cat, an obligate carnivore. Comparative Biochemistry and Physiology Part A: Physiology. 1996;114(3):205–209. doi: 10.1016/0300-9629(95)02133-7. .

7. Clark D.L, Clark R.A. Neutral point testing of color vision in the domestic cat. Experimental Eye Research. 2016;153:23–26. doi: 10.1016/j.exer.2016.10.002.

8. Daw N.W, Pearlman A.L. Cat colour vision: Evidence for more than one cone process. The Journal of Physiology. 1970;211(1):125–137. doi: 10.1113/jphysiol.1970.sp009270.

9. Douglas R.H, Jeffery G. The spectral transmission of ocular media suggests ultraviolet sensitivity is widespread among mammals. Proceedings of the Royal Society B: Biological Sciences. 2014;281(1780):20132995. doi: 10.1098/rspb.2013.2995.

10. Driscoll C.A, Menotti-Raymond M, Roca A.L, Hupe K, Johnson W.E, Geffen E, … Macdonald D.W. The near eastern origin of cat domestication. Science. 2007;317(5837):519–523. doi: 10.1126/science.1139518.

11. Eccles R. Autonomic innervation of the vomeronasal organ of the cat. Physiology and Behavior. 1982;28(6):1011–1015. doi: 10.1016/0031-9384(82)90168-8.

12. Feldman H.N. Methods of scent marking in the domestic cat. Canadian Journal of Zoology. 1994;72(6):1093–1099. doi: 10.1139/z94-147.

13. Fitzgerald O. Discharges from the sensory organs of the cat's vibrissae and the modification in their activity by ions. The Journal of Physiology. 1940;98(2):163–178. doi: 10.1113/jphysiol.1940.sp003841.

14. Grant R.A, Goss V.G.A. What can whiskers tell us about mammalian evolution, behaviour, and ecology?Mammal Review. 2021;n/a(n/a):1–16. doi: 10.1111/mam.12253.

15. Heffner R.S, Heffner H.E. Hearing range of the domestic cat. Hearing Research. 1985;19(1):85–88. doi: 10.1016/0378-5955(85)90100-5.

16. Heffner R.S, Heffner H.E. Sound localization acuity in the cat: Effect of azimuth, signal duration, and test procedure. Hearing Research. 1988;36(2):221–232. doi: 10.1016/0378-5955(88)90064-0.

17. Hendriks W.H, Moughan P.J, Tarttelin M.F. Body composition of the adult domestic cat (Felis catus). Journal of Animal Physiology and Animal Nutrition. 1997;77(1–5):16–23. doi: 10.1111/j.1439-0396.1997.tb00733.x.

18. Hoffmann F, Musolf K, Penn D.J. Ultrasonic courtship vocalizations in wild house mice: Spectrographic analyses. Journal of Ethology. 2012;30(1):173–180. doi: 10.1007/s10164-011-0312-y.

19. Hughes N.K, Price C.J, Banks P.B. Predators are attracted to the olfactory signals of prey. PLoS One. 2010;5(9):e13114. doi: 10.1371/journal.pone.0013114.

20. Hullár I, Fekete S, Andrásofszky E, Szöcs Z, Berkényi T. Factors influencing the food preference of cats. Journal of Animal Physiology and Animal Nutrition. 2001;85(7‐8):205–211. doi: 10.1046/j.1439-0396.2001.00333.x.

21. Kang I, Reem R.E, Kaczmarowski A.L, Malpeli J.G. Contrast sensitivity of cats and humans in scotopic and mesopic conditions. Journal of Neurophysiology. 2009;102(2):831–840. doi: 10.1152/jn.90641.2008.

22. Kenshalo D.R. The temperature sensitivity of furred skin of cats. The Journal of Physiology. 1964;172(3):439–448. doi: 10.1113/jphysiol.1964.sp007431.

23. Kenshalo D.R, Duncan D.G, Weymark C. Thresholds for thermal stimulation of the inner thigh, footpad, and face of cats. Journal of Comparative & Physiological Psychology. 1967;63(1):133–138. doi: 10.1037/h0024177.

24. Kovach J.K, Kling A. Mechanisms of neonate sucking behaviour in the kitten. Animal Behaviour. 1967;15(1):91–101 Retrieved from. http://www.sciencedirect.com/science/article/B6W9W-4JT84S7-K/2/d6214eaae66544eba317056a3a5a9053. .

25. Land M.F. Eye movements of vertebrates and their relation to eye form and function. Journal of Comparative Physiology. 2015;201(2):195–214. doi: 10.1007/s00359-014-0964-5.

26. Lei W, Ravoninjohary A, Li X, Margolskee R.F, Reed D.R, Beauchamp G.K, Jiang P.Functional analyses of bitter taste receptors in domestic cats (Felis catus). PLoS One. 2015;10:e0139670. doi: 10.1371/journal.pone.0139670.

27. LeMagnen J. In: Le gout et les' saveurs. Paris. Presse Universitaires de France; 1951.

28. Li X, Li W, Wang H, Bayley D.L, Cao J, Reed D.R, … Brand J.G. Cats lack a sweet taste receptor. Journal of Nutrition. 2006;136(7):1932S–1934S. doi: 10.1093/jn/136.7.1932S.

29. Mitchell D.E, Kaye M, Timney B. Assessment of depth perception in cats. Perception. 1979;8(4):389–396. doi: 10.1068/p080389.

30. Ofri J. Optics and physiology of vision. In: Gelatt K.N, ed. Essentials of veterinary ophthalmology. John Wiley and Sons; 2014:55–65.

31. Ollivier F.J, Samuelson D.A, Brooks D.E, Lewis P.A, Kallberg M.E, Komáromy A.M.Comparative morphology of the tapetum lucidum (among selected species). Veterinary Ophthalmology. 2004;7(1):11–22. doi: 10.1111/j.1463-5224.2004.00318.x.

32. Pekel A.Y, Mülazımoğlu S.B, Acar N. Taste preferences and diet palatability in cats. Journal of Applied Animal Research. 2020;48(1):281–292. doi: 10.1080/09712119.2020.1786391.

33. Raihani G, González D, Arteaga L, Hudson R. Olfactory guidance of nipple attachment and suckling in kittens of the domestic cat: Inborn and learned responses. Developmental Psychobiology. 2009;51(8):662–671. doi: 10.1002/dev.20401.

34. Steinberg R.H, Reid M, Lacy P.L. The distribution of rods and cones in the retina of the cat (Felis domesticus). Journal of Comparative Neurology. 1973;148(2):229–248. doi: 10.1002/cne.901480209.

35. Strain G.M. Hearing disorders in cats: Classification, pathology and diagnosis. Journal of Feline Medicine & Surgery. 2017;19(3):276–287. doi: 10.1177/1098612x17695062.

36. Thombre A.G. Oral delivery of medications to companion animals: Palatability considerations. Advanced Drug Delivery Reviews. 2004;56(10):1399–1413. doi: 10.1016/j.addr.2004.02.012.

37. Vitale Shreve K.R, Udell M.A.R. Stress, security, and scent: The influence of chemical signals on the social lives of domestic cats and implications for applied settings. Applied Animal Behaviour Science. 2017;187:69–76. doi: 10.1016/j.applanim.2016.11.011.

38. Yu H, Xing Y.-T, Meng H, He B, Li W.-J, Qi X.-Z, … Luo S.-J. Genomic evidence for the Chinese mountain cat as a wildcat conspecific ("Felis silvestris bieti") and its introgression to domestic cats. Science Advances. 2021;7(26):eabg0221. doi: 10.1126/sciadv.abg0221.

Chapter 1.2: Life stages

Abstract

Kittens change quickly from cute, furry babies to sleek, elegant adults. The environment affects the expression of genes of the cat from conception through to the end of life. There are distinct periods when developmental processes need to occur for the kitten to develop fully. Knowing these helps the clinician diagnose problems and also be proactive in helping owners with young kittens.

Keywords

Brain development; Development period; Kitten

The domestic cat has several life stages which are defined by developmental milestones and changes in the animal. Cats at different stages of their life will display different behaviours and have differing needs (as evidenced by the plethora of different commercial diets available).

The queen is pregnant for 9 weeks before giving birth to up to five kittens on average. The kittens progress through the life stages of neonate, juvenile, adolescence and adulthood. Each stage is associated with changes that take the kitten from an organism dependent upon a caregiver for its survival to an independent individual capable of adapting to a wide variety of environments and lifestyles.

1.2.1. Kittenhood

Kittens are fascinating creatures; a mix of cute little faces that trigger caring behaviours in people, sharp claws and ambush attacks. The development of the kitten from embryo through dependent kitten to stand-alone adult cat has been described. The milestones of development and how deficiencies in the environments of kittens affect their behaviour as adults help determine if an individual cat's behaviour is normal and appropriate or if it has developmental deficiencies. The interplay of genetics, learning and environment also helps in understanding the development and expression of mental health disorders in