Closure times of neurocranial sutures and synchondroses in Persian compared to Domestic Shorthair cats.

Human-directed selective breeding has modified the phenotype of the modern Persian cat towards an extreme brachycephalic phenotype ('peke-face' Persian), which originates from a spontaneous mutation that first appeared in the 1950s in traditional Persian types. It was suggested that the peke-face phenotype results from pathologic skull development and might represent a craniosynostosis of the coronal sutures. We followed this hypothesis and investigated the time dependent status of the neurocranial sutures and synchondroses in an ontogenetic series of doll-faced and peke-faced Persian cats compared to Domestic Shorthair cats (DSHs). Cranial suture closure was assessed by examining an ontogenetic series of formalin-fixed head specimens (n = 55) and dry skulls (n = 32) using micro-computed tomography. Sagittal, metopic, coronal and lambdoid sutures as well as intersphenoidal, spheno-occipital and spheno-ethmoid synchondroses were examined. Logistic regression analysis was performed to test the global effect of age on suture closure within a group of peke-face Persians, doll-face Persians and DSHs and the 50% probability of having a closed suture was calculated and compared between groups. Age was a perfect predictor for the condition of the coronal sutures in peke-face Persians. Coronal sutures were found to be closed at 0-0.3 months. In doll-face and DSHs, coronal sutures were open throughout the lifetime with the exception of a few very old cats. Results of this study confirmed a coronal craniosynostosis that likely causes the extreme brachycephalic skull morphology in the peke-face Persian.

Developmental genetics of color pattern establishment in cats.

Intricate color patterns are a defining aspect of morphological diversity in the Felidae. We applied morphological and single-cell gene expression analysis to fetal skin of domestic cats to identify when, where, and how, during fetal development, felid color patterns are established. Early in development, we identify stripe-like alterations in epidermal thickness preceded by a gene expression pre-pattern. The secreted Wnt inhibitor encoded by Dickkopf 4 plays a central role in this process, and is mutated in cats with the Ticked pattern type. Our results bring molecular understanding to how the leopard got its spots, suggest that similar mechanisms underlie periodic color pattern and periodic hair follicle spacing, and identify targets for diverse pattern variation in other mammals.

SMI-32 labeling in Cajal-Retzius cells of feline primary visual cortex.

Cajal-Retzius cells are one of the transient elements of the developing cerebral cortex. These cells express some characteristic molecules. One of them, heavy-chain neurofilaments, participating in the construction of the mature cerebral networks, are believed to be a specific feature of the human's Cajal-Retzius cells. Using histochemical stain for SMI-32 antibody to the non-phosphorylated heavy-chain neurofilaments, large neurons having horizontally oriented soma and bipolar processes were labeled in the molecular layer of the primary visual cortex of cats aged 0-2 postnatal days. Using DiI technique, similar neurons having a well-developed system of parallel vertical branches coming from the two horizontal processes were visualized in these areas. The location and general morphology of these neurons were similar to the Cajal-Retzius cells allowing to suppose for the carnivores to share similar with primates developmental mechanisms of the corticogenesis.

Sobrevida e características ecocardiográficas de gatos com e sem cardiomiopatias / Survival and echocardiographic characteristics of cats with and without cardiomyopathies

Cardiopatias felinas apresentam importante relevância na rotina veterinária, todavia os seus aspectos epidemiológicos em gatos não são conhecidos regionalmente. O objetivo do estudo foi descrever a frequência das cardiopatias na região Norte e Vale do Itajaí no estado de Santa Catarina e determinar a sobrevida de pacientes cardiopatas e não cardiopatas. O estudo contou com a análise retrospectiva de 74 laudos ecocardiográficos e prontuários médicos de gatos oriundos de estabelecimentos veterinários da região, de janeiro de 2017 a dezembro de 2019. Tutores ou veterinários responsáveis foram contatados para averiguar a sobrevida dos animais. Os animais do estudo em sua maioria eram machos (n=40/74) e sem raça definida (n=47/74). Cardiomiopatia foi o diagnóstico mais comum (n=21/74), com destaque para o fenótipo hipertrófica (n=13/21). As cardiomiopatias foram diagnosticadas mais comumente em gatos acima de oito anos de idade. Os principais sinais clínicos nos gatos sintomáticos (n=41/74) foram sopro (n=15/41) e dispneia (n=6/41). Os principais achados ecocardiográficos foram hipertrofia concêntrica da parede livre do ventrículo esquerdo (n=18/41) e dilatação do átrio esquerdo (n=12/41). A mediana de sobrevida dos 74 gatos foi de 303±209.8 dias, estando altamente relacionado com a classe do estadiamento clínico (P=0,006). Gatos com fenótipo dilatada tiveram menor média de sobrevid

Feline cardiopathies are relevant on veterinary practice although lack of regional epidemiogical description. The purpose of this study is to determine cardiopathy prevalence and survival of cardiac and non-cardiac patients on Santa Catarina’s northern and Itajai valley regions. The retrospective study included 74 echocardiographic exams and medical records from January 2017 to December 2019. Veterinarians and owners were contacted to check survival on cardiac and non-cardiac patients. The animals were most male (n=40/74) and mongrel (n=47/74). Cardiomyopathies were the most common diagnosis (n=21/74), specially the hypertrophic phenotype (n=13/21). The cardiomyopathy diagnosis was evidenced in cats above eight years old. The most usual clinical findings on symptomatic patients (n=41/74) were cardiac murmur (n=15/41) and dyspnea (n=6/41). Left ventricular free wall concentric hypertrophy (n=18/41) and left atrium dilation (n=12/41) were the main echocardiographic findings. Median survival from 74 cats was 303±209,8 days and related to clinical staging (p=0,006). Cats with dilated cardiomyopathy phenotype presented lower mean survival (180,5 days). Concomitant diseases included chronic renal disease (n=7/15), systemic arterial hypertension (n=5/15) and/or hyperthyroidism (n=3/15). In conclusion, cats with cardiomyopathies, symptomatic and with more advanced stages of cardiac remodeling, have shown to live less than those in early stage of heart disease. As well as patients with associated concomitant diseases, they had a lower life expectancy.

Radiographic study of the development of the pelvis and hip and the femorotibial joints in domestic cats.

OBJECTIVES: The aims of the present study were to monitor, by radiographic examination, the skeletal development of the pelvis and the femorotibial joints of the domestic cat from the first week of life until the closing of the growth plates. METHODS: Radiographic examinations were collected from 15 domestic cats at weekly intervals during the first month and every 2 weeks from the second to the fourth month of age. After that, examinations were performed monthly until the age of 18 months. RESULTS: The ischiopubic growth plate closed at 2 months of age, followed by the fusion of the iliopubic, ilioischial, proximal femoral, greater trochanter and proximal fibular growth plates. The distal femur and proximal tibial growth plates were the last to close, with fusion occurring at 18 months. The mean time to closure of the iliopubic, ilioischial and distal femoral growth plates was shorter in females. The ossification centers first appeared, in ascending order, beginning with the lesser trochanter, followed by the greater trochanter, proximal fibular epiphysis, tibial tuberosity, patella, ischial tuberosity and lateral sesamoid of the popliteus muscle. CONCLUSIONS AND RELEVANCE: The complete closure of the growth plates of domestic cats occurs at approximately 18 months of age. Skeletal maturation at approximately 18 months of age is an important parameter to be considered in radiographic evaluation of certain skeletal changes, evolution of fractures and nutritional imbalance.

Assessment of body weight for age determination in kittens.

OBJECTIVES: The objective of this study was to assess the utility of using body weight for age determination in kittens. METHODS: Medical records were reviewed for serial body weight measurements collected from neonatal kittens (up to 8 weeks of age) from a breeding colony of specific pathogen-free domestic shorthair cats and for single-point body weight measurements of privately owned pediatric kittens (6-20 weeks of age) presenting for elective sterilization. Body weights were compared with known dates of birth and age assessed by dental eruption in combination with developmental characteristics. RESULTS: The coefficient of determination (R2) between age and body weight in longitudinally sampled neonatal kittens was 0.88, while that for pediatric kittens sampled at a single time point was 0.54. Among neonatal kittens, predicted age based on the 1 lb (0.45 kg) of body weight gain per month of age guideline corresponded to within 1 week of actual age for 243 (98.8%), 234 (95.1%), 203 (82.5%) and 191 (77.6%) kittens at 2, 4, 6 and 8 weeks of age, respectively. Among pediatric kittens, predicted age based on this guideline corresponded to within 1 week of actual age for 24 (77.4%), 411 (67.5%), 170 (57.0%), 96 (46.6%), 23 (28.8%), 15 (27.8%), one (25%) and five (17.9%) kittens at 6, 8, 10, 12, 14, 16, 18 and 20 weeks, respectively. CONCLUSIONS AND RELEVANCE: Body weight was an effective means of predicting age in kittens through 10 weeks of age. Factors other than body weight should be considered when estimating kitten age beyond that time point.

Ultrastructural study of uterine epithelium in the domestic cat during prenatal development.

The study describes the sequence of ultrastructural changes of the endometrial lining epithelium, first in the primordial paramesonephric ducts, then in the differentiating uterine horns, and finally in the mature uterus. The research material comprised female fetuses of the domestic cat, aged 33-63 days post conceptionem (p.c.), and mature females. The ultrastructural observations of the developing epithelium were conducted using transmission electron microscopy (TEM) and light microscopy (LM). The results revealed two basic stages in the development of the uterine mucosal epithelium in the domestic cat: the development of the epithelium of the uterine segment of the paramesonephric ducts, lasting from day 33 to day 42 p.c., and the differentiation of this epithelium into the mucosal epithelium of the uterus, starting after day 42 p.c. and lasting until the end of the prenatal period. The epithelium of the uterine segments of the paramesonephric ducts is pseudostratified with a flat surface, all cells being characterized by the same distribution of desmosomes, ribosomes, rough endoplasmic reticulum (rER) cisternae, and mitochondria in the cytoplasm. The differentiating epithelium of the uterus after day 51 p.c. is pseudostratified with a varied height. In the epithelial cells there are increases of (i) the number and complexity of the junctional complexes, (ii) the number of invaginations of the lateral cell membranes, and (iii) the number of elongated mitochondria, and also there appear distended cisternae of the rER, lipid droplets and clusters of glycogen, which suggest increasing metabolism and secretory activity of the cells during the transformation of the epithelium.

The expression and localization of Toll-like receptors 2, 4, 5 and 9 in the epididymis and vas deferens of a adult tom cats.

Toll-like receptors (TLRs) are important molecules, which provide protection against infections of the reproductive tract. This study demonstrates for the first time the expression and localization patterns of TLRs in the caput, corpus and cauda segments of the epididymal duct (ED) and the vas deferens (VD) of adult domestic cats using immunohistochemistry and western blotting. While immunoblot analyses revealed relatively similar protein levels for TLRs 2, 4, 5, and 9 in three segments of the ED, the protein levels of TLR2 and TLR4 in the VD were found to be significantly higher than those measured in the ED segments (P < 0.05). On the other hand, immunostaining showed that TLRs exhibited regional- and cell-specific localization patterns. TLR2 and TLR5 were immunolocalized to the nucleus and cytoplasm of the principal cells in all ducts. TLR4 was restricted to the stereocilia, and TLR9 was located in the cytoplasm of the principal cells. Narrow cells displayed positive immunoreactions for TLR4 and TLR5. The basal cells of the different ED segments were positive for all four TLRs. TLR2, TLR5 and TLR9 were detected in the cytoplasmic droplets of the spermatozoa. TLR4 and TLR9 were detected along the entire length of the sperm tail, whilst TLR2 and TLR5 were absent in the midpiece. TLR2 and TLR5 were also detected in the equatorial segment of the sperm head. These results suggest that TLR2, TLR4, TLR5 and TLR9 are important not only for the protection of the ED, VD and spermatozoa but also for the maturation and storage of spermatozoa in the ED and VD, respectively.

Morphology and topography of internal reproductive organs in the female cat during prenatal and postnatal development: Scanning electron microscope and three-dimensional reconstruction study.

The study describes the morphology and topography of internal reproductive organs in the domestic cat from the early prenatal period to maturity, using macroscopic and scanning electron microscope (SEM) observations with three-dimensional (3D) reconstructions. Fifty-seven female cat fetuses aged between the 27th and 63rd day postconception (p.c.), two newborn cats, three juveniles (3-month-old) cats, and three mature (12-month-old) cats were used in the study. The age of fetuses was determined on the basis of the growth curve for the domestic cat. The rudiments of cat ovaries develop on the ventral surface of the mesonephroi and within 30 days p.c. move to the sides of the abdominal cavity, which is similar to the position of the ovaries in the adult cat. The mesonephroi regress at about the 50th day p.c., when the residual mesonephric ducts are still found in the lower part of the body of the uterus. The paramesonephric ducts develop on the lateral surface of the mesonephroi and by the 45th day p.c., differentiate into the uterine tubes and the uterus. The arrangement of the paramesonephric ducts in the abdominal cavity changes from the U- to the V-shaped system. The final topography of the uterine tubes is established between the 54th and 60th day p.c., as the uterine tubes become convoluted. Before the 54th day p.c., the uterine horns undergo rapid elongation and convolution, forming the W-shaped system. By the third month of postnatal life, the uterine horns become straight, as in the adult cat.

Ultrasonographic evaluation of ovarian morphology and blood flow in prepubertal and pubertal cats.

The aim of this study was to evaluate two-dimensional and Doppler ultrasonographic changes of feline ovaries before and during puberty. Nine, 3-month-old female cats were followed until puberty (Day 1). Two-dimensional and Doppler ultrasound evaluations of the ovaries were carried out on Days -50, -20, -7 and 1. Longitudinal and transverse sections of the ovaries were measured and all anechoic spherical structures were considered to be follicles. The number of follicles >1 mm and the maximum diameter of the largest follicle were recorded. Peak systolic velocity and end diastolic velocity of intraovarian arteries were also measured to automatically calculate the resistive index (RI). The mean ovarian longitudinal diameter increased gradually throughout the study from 8.6 to 10.7 mm (p < 0.05). While four cats presented multiple anechoic spherical structures <1 mm diameter throughout the study, the remaining five animals had these structures only on Days -50 and -20. On Days -20, -7 and 1, the mean number of follicles were 1.4 ± 0.7, 2.5 ± 0.8 and 4.8 ± 1 respectively (p < 0.01). The largest follicles at the same time points were 1.1 ± 0.2 mm, 1.9 ± 0.3 mm and 2.6 ± 0.5 mm respectively (p < 0.05). The RI of the intraovarian arteries declined throughout the study period (p < 0.01). It is concluded that, in female cats, ovarian dimensions, follicle number and intraovarian blood flow increased from 3 months of age to puberty.

Food intake and energy expenditure in growing cats with and without a predisposition to overweight.

Overweight and obesity are multifactorial diseases caused by an imbalance in energy metabolism. An underlying genetic predisposition is often a factor in these conditions. In the cat breeding family of the Institute of Animal Nutrition at the Vetsuisse Faculty, University of Zurich, a segregating overweight phenotype with a genetic contribution was observed. From this breeding family, 26 kittens were followed from birth up to 8 months of age. During this time, food intake was measured using an automatic feeding station, and energy expenditure was investigated using indirect calorimetry at the ages of 4 and 6 months. Dual-energy X-ray absorptiometry (DEXA) was performed and blood glucose, leptin and insulin were measured at the ages of 4, 6 and 8 months. The kittens were also weighed daily for the first 2 weeks of life, every second day until weaning and once per week until 8 months of age. The body condition score (BCS) was evaluated monthly between 2 and 8 months of age. The main finding of this study is that a predisposition to overweight is connected to a higher food intake early in life, with no significant alterations in energy expenditure. The leptin blood levels were related to body fat percentage, and insulin sensitivity did not seem to be affected.

Estudo retrospectivo da casuística de felinos domésticos no Hospital Veterinário da Universidade Federal de Minas Gerais, no período de 2005 a 2014 / Retrospective study of the case load of domestic cats at the Veterinary Hospital of the Universidade Federal de Minas Gerais from 2005 to 2014

O objetivo deste estudo foi caracterizar as doenças dos gatos domésticos provenientes dos casos de necropsia e histopatologia do Hospital Veterinário da Universidade Federal de Minas Gerais (HV/UFMG), de 2005 a 2014. Foram analisados 408 exames de necropsia e 197 de biópsias, segundo o sexo, a faixa etária e a raça. Os diagnósticos mais frequentes incluíram doenças infecciosas/inflamatórias ou parasitárias (22,5%), agentes físicos (18,1%), doenças proliferativas (15,2%) e degenerativas (13,5%). Politraumatismo (10,8%) foi responsável pelo maior número de mortes em felinos, sendo as chances três vezes maiores em animais com até 24 meses de idade (P=0,005 OR 3,47 [IC 95%: 1,40-8,57]). Neoplasias epiteliais corresponderam a 26 diagnósticos, sendo 20 (4,9%) casos de malignidade. A ocorrência de carcinoma e seus subtipos foi 18 vezes maior em gatos idosos (P<0,01 OR 18,15 [IC 95%: 7,41-44,45]). A insuficiência renal crônica foi mais frequente em gatos com mais de 120 meses (P=0,01). Machos apresentaram nove vezes mais chances de desenvolver doenças do trato urinário inferior quando comparados às fêmeas (P=0,001 OR 9,50 [IC 95%: 2,78-32,48]). Em relação às biópsias, animais adultos a idosos foram 10 vezes mais representados (P<0,001 OR 10,8 [IC 95%: 3,22-36,79]).(AU)

The aim of this study was to characterize the diseases of domestic cats based on necropsy and histopathological examinations at the Veterinary Hospital of the Universidade Federal de Minas Gerais (HV/UFMG) from 2005 to 2014. A total of 408 necropsy and 197 biopsy samples were analyzed according to gender, age, and breed. The most frequent diagnoses included infectious/inflammatory or parasitic diseases (22.5%), physical agents (18.1%), proliferative (15.2%), and degenerative (13.5%) diseases. Polytrauma (10.8%) was responsible for the highest number of feline deaths, with the odds three times higher in animals up to 24 months of age (P= 0.005 OR 3.47 [95% CI: 1.40-8.57]). Epithelial neoplasms corresponded to 26 diagnoses, with 20 (4.9%) malignant cases. The occurrence of carcinoma and its subtypes was 18-fold higher in older cats (P< 0.01 OR 18.15 [95% CI: 7.41-44.45]). Chronic renal failure was more frequent in cats over 120 months (P= 0.01). Males were nine times more likely to develop lower urinary tract diseases when compared to females (P= 0.001 OR 9.50 [95% CI: 2.78-32.48]). Regarding the biopsies, adult to elderly animals were ten times more represented (P< 0.001 OR 10.8 [95% CI: 3.22-36.79]).(AU)

Development and proliferation of feline endometrial glands from fetal life to ovarian cyclicity.

In this study it was determined the progression of uterine gland development from late gestation to puberty in domestic felids. Cell proliferation patterns for luminal (LE), glandular epithelium (GE) as well as stroma (S) were also described. Twenty-four uteri from female kittens: 45 and 65 days of gestation and 1 to 5, 8, 12, 16, 20 and 24 weeks postnatally were obtained. Uterine cross-sections were submitted for routine histological and immunohistochemical quantification of proliferating cell nuclear antigen (PCNA) techniques. Although prenatal uteri presented no indication of adenogenesis, 1 week old uteri revealed an incipient budding of the LE. During the second week budding increased and a mild degree of tubulogenesis of the GE into the stroma was detected. From the third to fifth weeks coiling, branching and cross-sections of glands appeared. These latter findings were more evident in week 8 when GE began to penetrate through much of the S to week 24. PCNA immunostaining revealed that DNA synthesis decreased throughout the study in the 3 cell compartments; (P < 0.01). Luminal proliferation began prenatally, it maintained up to postnatal week 8 to markedly decrease to puberty (P < 0.01). From postnatal week 3 up to week 8, GE mitotic activity was elevated becoming low thereafter (P < 0.01). Stroma actively proliferated prenatally (P < 0.01), diminishing up to week 8 (P < 0.01) and again during the last weeks (P < 0.01) of the study. It was concluded that, in domestic felids, proliferation of LE begins prenatally, histological uterine adenogenesis commenced during the first postnatal week and both events concluded by postnatal weeks 5-8.

Development of Deep and Upper Neuronal Layers in the Domestic Cat, Sheep and Pig Neocortex.

The neocortex plays a key role in cognition, volitional motor control and sensory perception and has undergone tremendous expansion during evolution. The mature neocortex consists of radially aligned neurons that are arranged in six layers. Layers II-VI are often split into two groups: deep and upper layers, both building up the so-called cortical plate during embryonic and foetal development. So far cortical neurogenesis, including the generation of deep and upper layers, has mostly been studied in laboratory rodents and primates. However, precise data for most companion animals are lacking. This study determined the main period of neurogenesis, specifically the timing of deep and upper layer generation, in the developing domestic cat, pig and sheep neocortex using immunohistochemistry for specific neuronal markers, that is Tbr1 and Brn2. We found that the general sequence of neural events is preserved among cat, pig, sheep and other mammalian species. However, we observed differences in the timing of the overall cortical neurogenic period and occurrence of distinct neural events when these three species were compared. Moreover, our data provide further evidence that the cortical neurogenic period and gestation length might be tightly related. Together, these data expand our current understanding of neocortex development and are important for future studies investigating neocortex development and expansion especially in companion animals.

Postponement of puberty in queens treated with deslorelin.

Objectives The purpose of this study was to assess efficacy of deslorelin, a gonadotropin-releasing hormone (GnRH) agonist marketed in Europe for the control of male dog reproduction, for the postponement of puberty in queens. Methods Nine prepubertal queens aged 3-9 months were selected for this study; their general and reproductive health was checked through clinical, haematological, vaginal cytology and hormonal tests. Following treatment with a 4.7 mg deslorelin implant, each cat received a monthly clinical examination and blood was collected for hormonal assay every third month. Cats were monitored for 14.1 ± 5.2 (range 7-23) months. Results All cats were in good body condition and normal health prior to treatment. Their health status remained unchanged throughout the study and no significant variation was observed with regard to serum progesterone or oestradiol. Seven days post-treatment, 1/9 queens showed signs of heat, and one other queen showed complete vaginal keratinisation. No other signs of heat were subsequently observed in any other queen. Five queens were lost during the study after 7, 7, 16, 17 and 18 months of observation (during which time they did not show signs of heat). By the end of the study, no sign of puberty was observed in the four remaining queens at 21-36 months of age. Conclusions and relevance A 4.7 mg deslorelin implant was able to suppress the feline pituitary-gonadal axis, leading to postponement of puberty for up to 21-36 months in the four queens that completed the study. Deslorelin can be considered as a safe method to postpone puberty in queens.

Evaluation of two raw diets vs a commercial cooked diet on feline growth.

Objectives The objective of this study was to determine if two raw feline diets were nutritionally adequate for kittens. Methods Twenty-four 9-week-old kittens underwent an Association of American Feed Control Officials' (AAFCO) 10 week growth feeding trial with two raw diet groups and one cooked diet group (eight kittens in each). Morphometric measurements (weight, height and length), complete blood counts, serum chemistry, whole blood taurine and fecal cultures were evaluated. Results Overall, the growth parameters were similar for all diet groups, indicating the two raw diets used in this study supported feline growth, within the limitations of an AAFCO growth feeding trial. Kittens fed the raw diets had lower albumin ( P = 0.010) and higher globulin ( P = 0.04) levels than the kittens fed the cooked diet. These lower albumin levels were not clinically significant, as all groups were still within normal age reference intervals. A red cell microcytosis ( P = 0.001) was noted in the combination raw diet group. Increases in fecal Clostridium perfringens were noted in all groups, along with positive fecal Salmonella serovar Heidelberg and Clostridium difficile toxin in the combination raw diet group. Conclusions and relevance The majority of the parameters for feline growth were similar among all groups, indicating the two raw diets studied passed an AAFCO growth trial. In theory, it is possible to pass an AAFCO growth trial but still have nutrient deficiencies in the long term due to liver and fat storage depots. Some of the raw feeders had elevated globulin and microcytosis, likely associated with known enteropathogenic exposure. Disease risks to both pets and owners are obvious. Additional research in this area is needed to investigate the impact of raw diets on the health of domestic cats.

Metabolic Profiling Reveals Effects of Age, Sexual Development and Neutering in Plasma of Young Male Cats.

Neutering is a significant risk factor for obesity in cats. The mechanisms that promote neuter-associated weight gain are not well understood but following neutering, acute changes in energy expenditure and energy consumption have been observed. Metabolic profiling (GC-MS and UHPLC-MS-MS) was used in a longitudinal study to identify changes associated with age, sexual development and neutering in male cats fed a nutritionally-complete dry diet to maintain an ideal body condition score. At eight time points, between 19 and 52 weeks of age, fasted blood samples were taken from kittens neutered at either 19 weeks of age (Early Neuter (EN), n = 8) or at 31 weeks of age (Conventional Neuter (CN), n = 7). Univariate and multivariate analyses were used to compare plasma metabolites (n = 370) from EN and CN cats. Age was the primary driver of variance in the plasma metabolome, including a developmental change independent of neuter group between 19 and 21 weeks in lysolipids and fatty acid amides. Changes associated with sexual development and its subsequent loss were also observed, with differences at some time points observed between EN and CN cats for 45 metabolites (FDR p<0.05). Pathway Enrichment Analysis also identified significant effects in 20 pathways, dominated by amino acid, sterol and fatty acid metabolism. Most changes were interpretable within the context of male sexual development, and changed following neutering in the CN group. Felinine metabolism in CN cats was the most significantly altered pathway, increasing during sexual development and decreasing acutely following neutering. Felinine is a testosterone-regulated, felid-specific glutathione derivative secreted in urine. Alterations in tryptophan, histidine and tocopherol metabolism observed in peripubertal cats may be to support physiological functions of glutathione following diversion of S-amino acids for urinary felinine secretion.

Regional variation of white matter development in the cat brain revealed by ex vivo diffusion MR tractography.

Three-dimensional reconstruction of developing fiber pathways is essential to assessing the developmental course of fiber pathways in the whole brain. We applied diffusion spectrum imaging (DSI) tractography to five juvenile ex vivo cat brains at postnatal day (P) 35, when the degree of myelination varies across brain regions. We quantified diffusion properties (fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) and other measurements (number, volume, and voxel count) on reconstructed pathways for projection (cortico-spinal and thalamo-cortical), corpus callosal, limbic (cingulum and fornix), and association (cortico-cortical) pathways, and characterized regional differences in maturation patterns by assessing diffusion properties. FA values were significantly higher in cortico-cortical pathways within the right hemisphere compared to those within the left hemisphere, while the other measurements for the cortico-cortical pathways within the hemisphere did not show asymmetry. ADC values were not asymmetric in both types of pathways. Interestingly, tract count and volume were significantly larger in the left thalamo-cortical pathways compared to the right thalamo-cortical pathways. The bilateral thalamo-cortical pathways showed high FA values compared to the other fiber pathways. On the other hand, ADC values did not show any differences across pathways studied. These results demonstrate that DSI tractography successfully depicted regional variations of white matter tracts during development when myelination is incomplete. Low FA and high ADC values in the cingulum bundle suggest that the cingulum bundle is less mature than the others at this developmental stage.

Ultrastructure of Developing Feline Nonciliated Bronchiolar Epithelial Cells.

The ultrastructure of the developing bronchiolar cell was studied in six age groups: prenatal (60 d post-conception); postnatal (1-, 7-, 14- and 21-day-old); and adult. Following intratracheal fixation, the lung tissue was processed for scanning and transmission electron microscopy. The lining of terminal bronchioles consists of cuboidal to columnar nonciliated bronchiolar cells (NBCs) and ciliated with or without microvilli. NBCs were recognized by indented centrally located nucleus. The apical surface extended beyond the surface of neighboring cells and was covered by minute microvilli, except in prenatal kittens. The NBCs of the adult were characterized by abundant mitochondria and glycogen inclusions. In prenatal kittens, the cytoplasm was filled with patches of alpha and beta form of glycogen. Postnatally, glycogen was reduced in quantity, became scattered throughout the cytoplasm and was predominantly of the beta form. Islands of cytoplasm, separated from the apical cytoplasm were observed in the lumen of adult bronchioles. This suggests an apocrine mode of secretion. The NBCs attain maturity by three weeks of age.