The effects of litter-size variation on the development of play behaviour in the domestic cat: litters of one and two

In many litter-bearing species, litter-mates interact with each other in a variety of ways during early life. In the domestic cat, Felis catus, social play is a prominent form of interaction between litter-mates. The present study investigated how the lack of a litter-mate affected the development of kitten play and of the mother-kitten relationship. The subjects were 14 litters of domestic kittens living with their mothers in large indoor cages. Seven litters contained two male kittens, and the other seven contained single male kittens. Social interactions within the families were observed from day 22 to day 83 after birth. Single kittens played a more active part in maintaining close proximity to their mothers and directed more playful behaviour at them than did kittens with a sibling. Although single-kitten mothers avoided their offspring more than did mothers of litters of two, they also directed much higher levels of play behaviour at them. Despite the marked difference in the mother-kitten play relationship in the two litter types, single kittens experienced quantitatively less social play than did kittens with siblings. As the kittens grew older, single-kitten mothers showed higher levels of aggression towards their young than did mothers of litters of two.     

The influence of experimentally manipulating a component of weaning on the development of play in domestic cats

Two previous studies found that simulating aspects of early weaning, starting 5 weeks after birth, increased the frequency of object play and, to a lesser extent, social play in kittens. The present study further investigated this finding, using the lactation-suppressing drug bromocriptine to simulate a component of early weaning (a reduction in maternal milk production). The experimental manipulation was started a week earlier in ontogeny than in the previous studies. The subjects were 14 litters of domestic kittens (Felis catus), living with their mothers in large indoor pens. Each litter consisted of two kittens. Seven Experimental (E) mothers were injected with bromocriptine on the 28th, 30th and 33rd days after their kittens were born. Seven Control (C) mothers were injected with saline. Observations of the kittens' social play, object play and locomotor play were carried out in each 3-day period from 36 to 60 days after birth. The E kittens showed significantly higher frequencies of a social play measure (Cat Contact) than the C kittens. However, object play was not significantly affected by the manipulation, in contrast to the previous studies. The E kittens also scored higher on a measure of locomotor play and fell off a climbing frame more often than the C kittens. E mothers played less than C mothers. Absolute frequencies of Cat Contacts and Object Contacts were higher in the present study than those previously reported.     

The consequences of differences in litter size for the nursing cat and her kittens

Seventy-one litters of kittens (mean litter size 4.4) were studied from birth to eight weeks of age in order to measure kitten growth and maternal body condition. Few sex differences in growth occur; male and female kittens place a similar burden on their lactating mother. A mother's weight (non-pregnant, non-lactating) interacts with litter size to determine the fate of her growing kittens. A large litter places a burden on both the mother and on the kittens, whose growth is affected; small mothers with large litters are particularly at risk. An acceleration in kitten growth occurs at about 32 days as the kittens take more solid food. This change in growth rate is more marked in large litters. Kittens of light mothers and kittens in large litters are weaned at a lower weight, and kittens of light mothers are weaned earlier. Our results indicate that, under poor environmental conditions, large litters would be less successful than small litters; kitten growth and survival would be affected and providing milk for a large litter would have a detrimental effect on the mother's health. The cost of lactation appears to have been a major evolutionary factor in determining mean litter size.     

Investigation of the faecal microbiota of kittens: monitoring bacterial succession and effect of diet

Weaning is a stressful process for kittens and is often associated with diarrhoea and the onset of infectious diseases. The gastrointestinal (GI) microbiota plays an essential role in host well-being, including improving homoeostasis. Composition of the GI microbiota of young cats is poorly understood and the impact of diet on the kitten microbiota unknown. The aims of this study were to monitor the faecal microbiota of kittens and determine the effect(s) of diet on its composition. Bacterial succession was monitored in two groups of kittens (at 4 and 6 weeks, and 4 and 9 months of age) fed different foods. Age-related microbial changes revealed significantly different counts of total bacteria, lactic acid bacteria, Desulfovibrionales, Clostridium cluster IX and Bacteroidetes between 4-week- and 9-month-old kittens. Diet-associated differences in the faecal microbiota of the two feeding groups were evident. In general, fluorescence in situ hybridization analysis demonstrated bifidobacteria, Atopobium group, Clostridium cluster XIV and lactic acid bacteria were dominant in kittens. Denaturing gradient gel electrophoresis profiling showed highly complex and diverse faecal microbiotas for kittens, with age- and/or food-related changes seen in relation to species richness and similarity indices. Four-week-old kittens harboured more diverse and variable profiles than those of weaned kittens.     

Communal nursing in the domestic cat,Felis catus

Communal nursing in the domestic cat has been observed in group living conditions. (In high density conditions, cats have social lives.) In our laboratory, when females were kept in the same cage, they delivered kittens nearly simultaneously, and started to nurse their kittens communally. This process, which was videotaped, was shown to be begun by the mother’s retrieving kittens. They seemed to have no ability to discriminate their own kittens from those of others, as our test of recognition of kittens showed. Communal nursing resulted in high mortality of kittens, the release of mothers from caring for kittens, and incomplete reproductive division of labour. Abortion was often observed in group-living cats in captivity. High mortality and low birthrate are helpful in controlling population. All members of the group were very familiar to each other, so that they formed a ‘pseudo’-kin group.     

Postnatal development of functional properties of the visual cortical cells of area 18 in kittens raised with or without visual experience

866 units were recorded extracellularly in area 18 of anaesthetized and paralysed kittens from 13 to 66 days of age. The development of their receptive field properties was studied in normally (EN) and dark-reared (EO) kittens. In addition to orientation selective (S) and non-selective (NS) cells, we found a number of non-selective units whose receptive field was surrounded by a peripheral zone (NSp) where stationary stimuli were effective. In EN kittens, the orientation selectivity developed with age and concomitantly, NS and NSp cells disappeared. Ocular dominance distribution was also gradually modified from a contralateral monocular dominance at 13 days of age to an adult-like binocularity at 58 days. In EO kittens, the early orientation selectivity began to decrease at the 5th week. From then on, the process of despecification started and progressed until nearly all cells were NS. Absence of visual experience also delayed the development of mature binocularity. In 6 week old EO kittens, a 6 hrs. visual exposure induced a fast but uncomplete specification with decrease of both NS and NSp cells and a slight modification of the ocular dominance distribution. The comparison of these results with those obtained in area 17 shows that functional properties vary more slowly in area 18 than in area 17.     

Analysis of the layer distribution of transcallosal responses in the sensorimotor cortex of kittens in the 1st month of life

In experiments on 23 kittens ageing between 1-30 days, anaesthetized by barbiturate and immobilized by diplacine, studies have been made on the distribution of transcallosal responses (TCRs) along the whole diameter of the sensorimotor cortex. In order to obtain more accurate data on localization of the sources and drains of extracellular current vertical component, a method of double graphic differentiation was used. It was shown that in 1-2-day kittens TCRs have a positive oscillation form throughout all the depth of recording. During the 1st week, TCRs from the cortical surface acquired a positive-negative configuration, remaining mostly positive in deeper layers. At this ontogenetic stage, the drain of positive-negative oscillation is focused in the layer I. In 2-3-week kittens, positive-negative potentials on the surface were transformed into negative-positive responses in deep layers. The drains of this deep negative component were localized in the layers III and V-VI. On the 4th week, positive-negative TCRs on the surface changed into negative-positive potentials at various depths depending on the spatial position of the recording point. The drain of deep-laid negative component in the focus of maximum activity was found in the layer V, out of its boundaries--in the layers II-III. Ontogenetic dynamics was revealed of current drains localization of both TCRs components in the sensorimotor cortex in new-born kittens.     

Taurine in the developing cat: Uptake and release in different brain areas

Taurine is an important modulator of neuronal activity in the immature brain. In kittens, taurine deficiency causes serious dysfunction in the cerebellar and cerebral visual cortex. The processes of taurine transport in vitro were now studied for the first time in different brain areas in developing and adult cats. The uptake of taurine consisted initially of two saturable components, high- and low-affinity, in synaptosomal preparations from the developing cerebral cortex and cerebellum, but the high-affinity uptake component completely disappeared during maturation. The release of both endogenous and preloaded labeled taurine from brain slices measured in a superfusion system was severalfold stimulated with a slow onset by depolarizing K⁺ (50 mM) concentrations. K⁺ stimulation released markedly more taurine from the cerebral cortex, cerebellum and brain stem in kittens than in adult cats. The responses were largest in the cerebellum. Both uptake and release of taurine are thus highly efficient in the brain of kittens and may be of significance in view of the vulnerability of cats to taurine deficiency.     

Questionnaire-based survey of parturition in the queen

The lack of scientific data concerning whether parturition in the queen proceeds normally or not may prevent veterinarians and cat owners from recognizing parturition problems in time. A questionnaire-based study of parturition in 197 queens was performed to determine several parameters of parturition and their influence on its progress. The mean length of gestation was 65.3 days (range 57 to 72 days) and it decreased with increasing litter size (P = 0.02). The median litter size was 4.5 kittens (range 1 to 9), with more males (53%) than females (46%) (P = 0.05). Sixty-nine percent of the kittens were born in anterior presentation and 31% in posterior presentation, indicating that either can be considered normal in the cat. Males were born in posterior position (34%) more often than females (26%) (P = 0.03). The mean birth weight was 98 g (range of 35 to 167 g) and decreased with increasing litter size (P < 0.01). Mean birth weight was higher in males and kittens born in posterior presentation (P < 0.01). Forty-four (5%) of the 887 kittens were stillborn. This was not correlated with the presentation at expulsion but stillborn kittens were more often female (P = 0.02) and weighed less than those born alive (P = 0.04). The median interkitten time was 30 min (range 2 to 343 min) and 95% were born within 100 min after expulsion of the preceding kitten. The interkitten time as a measure of the progress of parturition was not influenced by the kitten's gender, presentation at expulsion, birth weight, or stillbirth, or by the parity of the queen. The results of this study can be used to develop reference values for parturition parameters in the queen, both to determine whether a given parturition is abnormal and as the basis for a parturition protocol.     

Taurine deficiency in the kitten subcellular distribution of taurine and [35S]taurine in brain

Taurine concentration decreases rapidly in the tissues and physiological fluids of kittens fed a diet of partially purified casein which lacks taurine. We have studied the subcellular distribution in cerebrum of taurine and [³⁵S]taurine administered intravenously to these animals. The taurine concentration of all the fractions isolated from the cerebrum of taurine-deficient kittens was approximately sevenfold less than that observed in the fractions of cerebrum isolated from control kittens. The [³⁵S]taurine was approximately twofold greater in all the brain fractions isolated from the taurine-deficient kittens compared with those isolated from the control kittens. The percent distributions of taurine and [³⁵S]taurine in the fractions isolated from the cerebrum of control and deficient kittens were identical. Thus, in the face of a severe diet-induced deficiency of taurine in kitten brain, there appears to be no conservation of taurine by any particular subcellular pool of taurine. These studies provide no evidence for differences in compartmentation of taurine in cerebrum of taurine-deficient kittens compared with control kittens.     

Functional magnetic resonance imaging during hypotension in the developing animal.

Hypotension in adult animals recruits brain sites extending from cerebellar cortex to the midbrain and forebrain, suggesting a range of motor and endocrine reactions to maintain perfusion. We hypothesized that comparable neural actions during development rely more extensively on localized medullary processes. We used functional MRI to assess neural responses during sodium nitroprusside challenges in 14 isoflurane-anesthetized kittens, aged 14-25 days, and seven adult cats. Baseline arterial pressure increased with age in kittens, and basal heart rates were higher. The magnitude of depressor responses increased with age, while baroreceptor reflex sensitivity initially increased over those of adults. In contrast to a decline in adult cats, functional MRI signal intensity increased significantly in dorsal and ventrolateral medullary regions and the midline raphe in the kittens during the hypotensive challenges. In addition, significant signal intensity differences emerged in cerebellar cortex and deep nuclei, dorsolateral pons, midbrain tectum, hippocampus, thalamus, and insular cortex. The altered neural responses in medullary baroreceptor reflex sites may have resulted from disinhibitory or facilitatory influences from cerebellar and more rostral structures as a result of inadequately developed myelination or other neural processes. A comparable immaturity of blood pressure control mechanisms in humans would have significant clinical implications.     

Congenital transmission of Schistosoma japonicum in the rabbit

Fourteen pregnant rabbits were each infected with 300 cercariae of Schistosoma japonicum and divided into two groups. Group M (n = 8) was infected during mid-gestation (the organogenetic stage) and group L (n = 6) was infected during late-gestation (the post-organogenetic stage). Mother rabbits and rabbit kittens were killed 45-60 days after infection and perfused in order to obtain worm counts. Furthermore, faecal egg counts and tissue egg counts from livers were obtained from the mother rabbits as well as the rabbit kittens. All mother rabbits became infected harbouring 207.6 +/- 20.2 and 220.0 +/- 27.5 adult worms in group M and L, respectively. In groups M and L, 13.5% and 46.7% of the kittens were infected, respectively. In 12 of 14 litters at least one kitten was infected. The infected kittens harboured between one and three adult S. japonicum. The livers of the kittens infected with a worm pair displaced lesions as a result of egg deposition. The results, therefore, show that congenital transmission of S. japonicumcan occur in rabbits. The close anatomical resemblance between the rabbit and human placenta may be indicative of the presence of congenital transmission of S. japonicum infection in humans.     

Bartonella Infection among Cats Adopted from a San Francisco Shelter,Revisited

Bartonella infection among cats from shelters can pose a health risk to adopters. Bartonella henselae is the most common species, with B. clarridgeiae and B. koehlerae being less common. The lower rates of infection by the latter species may reflect their rarity or an inefficiency of culture techniques. To assess the incidence of infection, blood cultures, serology, and PCR testing were performed on 193 kittens (6 to 17 weeks old) and 158 young adult cats (5 to 12 months old) from a modern regional shelter. Classical B. henselae culture medium was compared to a medium supplemented with insect cell growth factors. Bartonella colonies were isolated from 115 (32.8%) animals, including 50 (25.9%) kittens and 65 (41.1%) young adults. Therefore, young adults were twice as likely to be culture positive as kittens. Enhanced culture methods did not improve either the isolation rate or species profile. B. henselae was isolated from 40 kittens and 55 young adults, while B. clarridgeiae was cultured from 10 animals in each group. B. koehlerae was detected in one young adult by PCR only. B. henselae genotype II was more commonly isolated from young adults, and genotype I was more frequently isolated from kittens. Kittens were 4.7 times more likely to have a very high bacterial load than young adults. A significantly higher incidence of bacteremia in the fall and winter than in the spring and summer was observed. Bartonella antibodies were detected in 10% (19/193) of kittens and 46.2% (73/158) of young adults, with culture-positive kittens being 9.4 times more likely to be seronegative than young adults.     

Behavioural observations of interactions in a free-ranging lynxLynx lynx family at kills

The behaviour of a free-ranging female lynxLynx lynx Linnaeus, 1758 and her kittens at 12 different kills was studied for 44 hours of observation from September 1996 to March 1997. The development of interactions at kills of a lynx family group showed the following pattern: until the end of September we often observed two lynx, usually both kittens, feed from the kill at the same time. After the age of four months aggression between kittens was observed frequently, with the bigger kitten being dominant. From September the kittens were never again seen feeding together at the kill. However, we never observed fighting, and aggressive behaviour did not increase with the age of the kittens. Whereas until December one of the kittens was always first at the kill, from January onwards it was mostly the adult female who ate first. She introduced her kittens to the home range of a neighbouring female where the family break-up occurred. The kittens were last seen together with their mother on 26 March. Dispersal seemed to be initiated by the female abandoning the kittens.     

Serologic and virologic surveys on feline herpesvirus and feline calicivirus infections in cats for experimental use

Serologic survey and virus isolation of feline herpesvirus (FHV) and feline calicivirus (FCV) were performed on cats used for research at the Laboratory Animal Research Centre, The University of Tsukuba, over the period from 1978 to 1981. Of the 507 mature and immature cats, 4 months old or older, 102 (20.1%) had HI antibody against FHV and 412 (81.3%) SN antibody against FCV. Some 23 (16.2%) and 76 (53.5%) kittens among 142 younger than 4 months had antibodies against FHV and FCV, respectively. Both the antibodies in kittens were considered to be maternally derived. The FCV antibody rate was especially high in cats weighing 2.5 kg (males) and 2.0 kg (females) or more, which were regarded as 8 to 10 months of age. An attempt was made to isolate the viruses from the oropharynx and conjunctiva of clinically healthy mature or immature cats and kittens. As the result, either one or both of the viruses were isolated from 31 of 75 mature and immature cats, and isolation rates of FHV and FCV were 6.7% and 36.0%, respectively. On the other hand, no virus was detectable in 16 kittens.     

Increased levels of testosterone have little effect on visual cortex plasticity in the kitten

We tested the hypothesis that increased levels of sex steroids preceding puberty are an important factor in the termination of the critical period for monocular deprivation. Male kittens were injected with Depo-testosterone in order to elevate plasma testosterone to a higher level than that in normal prepubertal male kittens. Control animals did not receive testosterone injections. All kittens were monocularly deprived for 7-18 days, then cells in the visual cortex were examined electrophysiologically, and an ocular dominance histogram was constructed. Treated animals showed an increase in plasma testosterone (1.82-15.16 ng/mL) when compared with the control animals (0.80 +/- 0.25 ng/mL). The fraction of cells driven exclusively by the experienced eye was slightly lower in the treated animals, and there was a slight increase in the dominance of cells by both eyes. However, in both groups of animals, the majority of cells were dominated by the experienced eye, with no significant difference in the weighted parameter used to describe this dominance. In summary, although there is a slight difference between treated and control animals, the results do not support the hypothesis that elevated levels of sex steroids play a crucial role in the termination of the critical period.     

Relative growth of the anulus fibrosus and nucleus pulposus in human and kitten fetuses

Growth in volume of the anulus fibrosus (AF) and nucleus pulposus (NP) was quantified using serial histological sections of human and kitten fetuses. Fetal intervertebral discs were studied that had clearly outlined AF and NP. Regression equations were calculated and graphs plotted by microcomputer. An increase in surface areas of these intervertebral structures was also recorded; however, volume was a better indicator of relative growth than was surface area. The AF volume of the fetal human increased more in proportion to the intervertebral disc than it did for the fetal kittens. There was significantly slower growth of the human NP compared to the kitten NP when related to the total intervertebral disc. The analysis for each species was done separately. Comparisons of the growth relationships of humans and kittens for the AF and NP were related to crown-rump length as the independent variable, and were different at the p less than or equal to 0.01 level of significance. The thoracic intervertebral discs were emphasized due to species-specific differential growth of the AF. The intercapital ligament (IC) was separated from mesenchyme over the dorsal surface of the kitten AF, and this affected the relationships of AF and NP volumes when compared to humans. Use of human histological sections is essential in the study of differential growth of the human vertebral column because fetal kittens have an IC that affects relative growth of both AF and NP.     

Vaccination against Feline Panleukopenia: implications from a field study in kittens

ABSTRACT: BACKGROUND: Feline Panleukopenia (FPL) is a serious disease of cats that can be prevented by vaccination. Kittens are routinely vaccinated repeatedly during their first months of life. By this time maternally derived antibodies (MDA) can interfere with successful vaccination and inhibit the development of active immunity. The efficacy of primary vaccination under field conditions was questioned by frequent reports to the Paul-Ehrlich-Institut on outbreaks of FPL in vaccinated breeding catteries. We therefore initiated a field study to investigate the development of immunity in kittens during primary vaccination against FPL. 64 kittens from 16 litters were vaccinated against FPL at the age of 8, 12 and 16 weeks using three commercial polyvalent vaccines. Blood samples were taken before each vaccination and at the age of 20 weeks. Sera were tested for antibodies against feline panleukopenia virus (FPV) by hemagglutination inhibition test and serum neutralisation assay in two independent diagnostic laboratories. RESULTS: There was a good correlation between the results obtained in different laboratories and with different methods. Despite triple vaccination 36.7% of the kittens did not seroconvert. Even very low titres of maternally derived antibodies (MDA) apparently inhibited the development of active immunity. The majority of kittens displayed significant titres of MDA at 8 and 12 weeks of age; in some animals MDA titres that interfered with vaccination were still detected at 20 weeks of age. Interestingly, the vaccines tested differed significantly in their ability to overcome low levels of maternal immunity. CONCLUSIONS: In the given situation it is recommended to quantify antibodies against FPV in the serum of the queen or of the kittens before primary vaccination of kittens. The beginning of primary vaccination should be delayed until MDA titres have declined. Unprotected kittens that have been identified serologically should be revaccinated.     

DNA methylation status in somatic and placenta cells of cloned cats

We recently produced 11 cloned kittens by somatic cell nuclear transfer (SCNT) using fibroblasts from a feline fetus (donor A, three kittens), an adult domestic cat (donor B, one kitten), and a deaf adult Turkish Angora cat (donor C, seven kittens). Two kittens were stillborn and three died a month after birth. The donor C-derived kittens did not share their donor's eye color or deafness. To test whether this and the low cloning success rate are due to epigenetic modifications, we compared the methylation of somatic and placental cells from the cloned cats and domestic normal cats by bisulfite mutagenesis sequencing analysis. The DNA methylation of somatic cells from the cloned kittens ranged from 78.0% to 88.9%, and did not differ significantly depending on whether they were stillborn, died early after birth, or were healthy. Donors B and C showed similar levels of methylation (77.0% and 79.1%, respectively), as did somatic cells from normal domestic and Turkish Angora cats (range, 75.7-88.0%). However, donor A showed less methylation (70.6%) than the somatic cells from the kittens derived from it (range, 82.2-88.9%). Moreover, placental cells from three donor C-derived kittens showed significantly higher DNA methylation (range, 76.7-80.5%) than placental cells from normal domestic cats (range, 64.2-74.9%). Thus, methylation of satellite regions in somatic cells may not be responsible for the stillbirth, early death, or different eye and hearing attributes of cloned cats. However, hypermethylation in the placenta of cloned cats may be responsible for low success rates in cloning cats.     

Posttetanic changes in the afferent and efferent activity of monosynaptic reflex in kittens

Both the afferent volleys from the dorsal root and the monosynaptic reflex discharges from the corresponding ventral root were recorded with hook electrodes during stimulation of the nerves innervating the triceps surae muscles. The effects of conditioning high frequency tetanus on the magnitudes of these afferents and reflex volleys were examined in kittens of postnatal age 1-90 days and in adult cats. In young kittens under barbiturate anaesthesia, large-amplitude monosynaptic reflex discharge can be evoked without prior conditioning. The amplitude of this reflex discharge decreased with increasing age of the animal. Application of conditioning tetanic stimuli to the muscle nerves resulted in posttetanic depression followed by posttetanic potentiation of the monosynaptic reflex. The magnitude of posttetanic depression was much higher than that of potentiation in the first postnatal week. As the age increased, the magnitude of depression decreased while the magnitude of potentiation increased. The afferent volley showed a considerable posttetanic potentiation in older kittens and cats. No significant potentiation or depression was observed in the younger animals. Possible mechanisms contributing to posttetanic depression and potentiation are discussed.