Geriatric Animals Research Articles

Comparison of the efficacy of royal jelly and melatonin combinations in experimentally induced wounds in geriatric and young mice.

Wound healing involves the repair of skin and other soft tissues after an injury. Royal jelly, a product of bees, possesses antioxidant, anti-inflammatory, antibacterial, and antiviral properties. Melatonin, a circadian indoleamine, is produced in the pineal gland and other organs. This study explores the effects of melatonin and royal jelly, both individually and combined, on wound healing in geriatric and young mice. The study includes 90 Balb/C mice divided into ten groups to assess the effects of royal jelly and melatonin on wound healing. Royal jelly was applied topically at a concentration of 300 mg/kg. Melatonin was formulated in a vaseline-based pomade at a concentration of 5 mg/kg. The substances were applied either separately or in combination to wounds created on the mice. Both substances significantly enhanced wound healing at a macroscopic level in both age groups. Melatonin was found to be more effective during the initial wound formation process, whereas royal jelly was more beneficial during the granulation phase. However, significant results at a histopathological level were observed only in geriatric animals. The findings suggest a potential new therapeutic approach to enhance wound healing, particularly in elderly individuals. However, these findings need to be supported through further research and clinical trials.

Ocular examination findings and selected ophthalmic diagnostic tests in African green monkeys (Chlorocebus aethiops sabaeus).

To document ocular lesions and establish ophthalmic diagnostic test reference values in a colony of African green monkeys (Chlorocebus aethiops sabaeus). Fifty one geriatric (GAGM, 19-30 years old), 10 adult (AAGM, 5-9 years old) and 10 juvenile (JAGM, <2 years old) African green monkeys housed in a single Caribbean research colony. Ocular biomicroscopy, indirect fundoscopy, Schirmer tear test (STT), rebound tonometry (TonoVet®) and corneal fluorescein staining were performed. Mixed ANCOVA tests were performed to compare STT and IOP between groups. Common ocular lesions in GAGM included vitreal degeneration (27/51, 51/102 eyes) and cataracts (21/51, 32/102 eyes). Vitreal degeneration was also common in AAGM (8/10, 16/20 eyes) and infrequent in JAGM (3/10, 6/20 eyes). Cataracts were not present in any JAGM or AAGM. All eyes in all three groups had perilimbal corneal pigmentation and faint lace-like anterior corneal stromal opacification. Median (range) STT values were 16.0 (18) mm/min in GAGM. Mean (SD) STT values were 14.2 (4.6) mm/min in AAGM, and 8.9 (3.4) mm/min in JAGM. Median (range) IOP values were 16.5 (27) mmHg in GAGM. Mean (SD) IOP values were 18.0 (2.8) mmHg in AAGM, and 14.1 (2.2) mmHg in JAGM. JAGM had significantly lower STT and IOP values compared to AAGM (p = .0449, .0057, respectively) and GAGM (p = .0002, .0130, respectively). Spontaneous ocular lesions were common in geriatric monkeys in this research colony. IOP and STT values were lower in juvenile African green monkeys relative to adult or geriatric animals.

DISEASE PROCESSES IDENTIFIED IN CAPTIVE ARABIAN SAND CATS (FELIS MARGARITA HARRISONI).

The objective of this retrospective study is to identify common and significant causes of mortality and disease processes in the Arabian sand cat (Felis margarita harrisoni) captive population at Al Ain Zoo (Abu Dhabi, United Arab Emirates). Complete postmortem records of 25 Arabian sand cats, dead between 2009 and 2022, were reviewed retrospectively. A complete postmortem examination was done in all cases, and information was recorded in the Al Ain Zoo database and files. Out of 25 animals dead, 11 were adults (4-12 yr) and 12 were classified as geriatric animals (>12 yr), with only two neonatal (0-4 mon) deaths and no recorded deaths in juveniles (4 mon to 4 yr). Interestingly, but also expected because of the age range, 24% of the cases had concurrent pathologies at the time of death. As expected in adult and geriatric felines, more than half of the cases (60%) developed nephropathies that were either one of the most important contributors or the main cause of death of the animal. Different neoplastic lesions were described in four cases and reported for the first time in this subspecies: benign peripheral nerve sheath tumor, hepatobiliary carcinoma, and two different thyroid neoplasia. A vasculoproliferative disorder of the liver, peliosis hepatis, was described in one of the cases. Additionally, in at least four cases, hyperthyroidism was strongly suspected in connection with thyroid neoplasia and hyperplasia, clinical signs, and other observed postmortem lesions. Traumatic causes of death also were reported in six cases, including the only two neonates recorded dead. This information will contribute to Arabian sand cat improved veterinary care by identifying common pathologies in this species, potentially allowing earlier diagnosis and, ultimately, improving their management and husbandry in the captive breeding populations.

Comprehensive longitudinal non-invasive quantification of healthspan and frailty in a large cohort (n = 546) of geriatric C57BL/6J mice.

Frailty is an age-related condition characterized by a multisystem functional decline, increased vulnerability to stressors, and adverse health outcomes. Quantifying the degree of frailty in humans and animals is a health measure useful for translational geroscience research. Two frailty measurements, namely the frailty phenotype (FP) and the clinical frailty index (CFI), have been validated in mice and are frequently applied in preclinical research. However, these two tools are based on different concepts and do not necessarily identify the same mice as frail. In particular, the FP is based on a dichotomous classification that suffers from high sample size requirements and misclassification problems. Based on the monthly longitudinal non-invasive assessment of frailty in a large cohort of mice, here we develop an alternative scoring method, which we called physical function score (PFS), proposed as a continuous variable that resumes into a unique function, the five criteria included in the FP. This score would not only reduce misclassification of frailty butit also makes the two tools, PFS and CFI, integrable to provide an overall measurement of health, named vitality score (VS) in aging mice. VS displays a higher association with mortality than PFS or CFI and correlates with biomarkers related to the accumulation of senescent cells and the epigenetic clock. This longitudinal non-invasive assessment strategy and the VS may help to overcome the different sensitivity in frailty identification, reduce the sample size in longitudinal experiments, and establish the effectiveness of therapeutic/preventive interventions for frailty or other age-related diseases in geriatric animals.

Disease Complication in a Geriatric Pig-Tailed Macaque (Macaca nemestrina) reported from Wildlife Rescue Centre (WRC) Jogja – Case Study

In the current study, a geriatric male pig-tailed macaque having a mass growing up to the left shoulder for the past five months has been reported from the Wildlife Rescue Centre (WRC) Jogja. It was an approximately 4x4x2 cm, firm, hairless focal non-encapsulated mass suspected as a skin-derivative tumor. A cytological test was performed on the mass and a skin biopsy was carried out to see the tissue content of the mass. Histopathological examination confirmed that the mass was identical to papilloma. In the next step of the study, the surgery was conducted and the mass was removed. However, after surgery, the health condition of the macaque gradually deteriorated and the performed hematological tests revealed a gradual increase in the number of leukocyte cells that indicated a developing chronic inflammatory response. Further, the erythrocyte level was in the normal range but showed a declining trend which suspecting progressing anemia. One month after the surgery general muscle stiffness was reported in the macaque which is a clinical sign of tetanus and the macaque died even after the ATT serum treatments. Necropsy findings confirmed a significant chronic bilateral diffuse pneumonia. This case study showed an unpredicted sequence of disease occurrence in geriatric macaque after undergoing the initial surgery of cutaneous mass extraction. Hence, the results of the study suggest that a routine regular health screening coupled with clinical laboratory examination may assist the early detection based on the subclinical signs of disease in geriatric animals in rehabilitation centers.

RETROSPECTIVE ANALYSIS OF MORTALITY CAUSES IN MANAGED KIRK'S DIK-DIKS (MADOQUA KIRKII) IN NORTH AMERICA FROM 1988 to 2019.

Kirk's dik-diks (Madoqua kirkii) are the most common dik-dik species managed in North American zoological institutions, but their numbers are declining at a concerning rate, with less than 40 individuals currently housed in accredited institutions. This retrospective study reports the causes of mortality in Kirk's dik-diks in North American zoological institutions from 1988 to 2019. Out of 15 institutions accredited by the Association of Zoos and Aquariums (AZA) currently housing Kirk's dik-diks, nine contributed to this study (60% participation). Eighty-four necropsy records were reviewed to determine the primary affected body system and etiological cause of death across and within age categories. Neonatal death (prior to 1 mon of age) was most common (38.1%), followed by death in adults (29.8%), geriatric animals (19.0%), and juveniles (13.1%). As a whole population, causes of death by body system were multisystemic (47.6%), musculoskeletal (15.5%), respiratory (8.3%), and digestive (8.3%). Neonatal complications accounted for 50.0% of all deaths in animals prior to 1 mon of age. In juveniles, a nutritional cause of death was most common (27.3%) and significantly higher compared to measures of this cause within other age categories. In adults, metabolic etiologies and trauma each accounted for 28.0% of deaths. Degenerative etiologies were most common in geriatric individuals, representing 31.3% of the deaths. Death from infectious disease was found across all ages, representing 11.9% of all mortalities. Results from this study provide a baseline reference for this species and may aid clinicians in decision-making as it relates to the medical care and management of this species during different life stages.

Conditional loss of IKK\u03b1 in Osterix\u2009+\u2009cells has no effect on bone but leads to age-related loss of peripheral fat

NF-κB has been reported to both promote and inhibit bone formation. To explore its role in osteolineage cells, we conditionally deleted IKKα, an upstream kinase required for non-canonical NF-κB activation, using Osterix (Osx)-Cre. Surprisingly, we found no effect on either cancellous or cortical bone, even following mechanical loading. However, we noted that IKKα conditional knockout (cKO) mice began to lose body weight after 6 months of age with severe reductions in fat mass and lower adipocyte size in geriatric animals. qPCR analysis of adipogenic markers in fat pads of cKO mice indicated no difference in early differentiation, but instead markedly lower leptin with age. We challenged young mice with a high fat diet finding that cKO mice gained less weight and showed improved glucose metabolism. Low levels of recombination at the IKKα locus were detected in fat pads isolated from old cKO mice. To determine whether recombination occurs in adipocytes, we examined fat pads in Osx-Cre;TdT reporter mice; these showed increasing Osx-Cre-mediated expression in peripheral adipocytes from 6 weeks to 18 months. Since Osx-Cre drives recombination in peripheral adipocytes with age, we conclude that fat loss in cKO mice is most likely caused by progressive deficits of IKKα in adipocytes.

Factors Affecting Hematologic and Serum Biochemical Parameters in Healthy Common Marmosets (Callithrix jacchus).

Physiologic changes during development, aging, and pregnancy may affect clinical parameters. Previously available reference values have been based on samples that may include wild and captive marmosets, with little representation of geriatric or pregnant animals. Establishing reference values under various conditions would support better recognition of pathologic conditions in marmosets. One hundred and forty-seven (70 males and 77 females) healthy marmosets from a research colony were included in this study. Exclusion criteria were abnormal physical exam findings at the time of blood sampling, chronic medications, or clinical or pathologic evidence of disease. Reference intervals were calculated for serum chemistry and hematology. Using metadata, samples were classified based on age, sex, colony source and pregnancy status. Multiple tests indicated significant differences with varying effect sizes, indicating that developing reference intervals based on metadata can be useful. Across all the comparisons, medium or large effect sizes were observed most frequently in blood urea nitrogen (BUN), calcium, total protein, alkaline phosphatase (ALP), weight and serum albumin. We report normative clinical pathologic data for captive common marmosets through all life stages and reproductive status. Significant differences were observed in most parameters when stratifying data based on age, sex, colony source, or pregnancy, suggesting that developing reference intervals considering this information is important for clinicians.

Canine Geriatric Rehabilitation: Considerations and Strategies for Assessment, Functional Scoring, and Follow Up.

Geriatric animals account for half of the pet population in the United States with their numbers increasing annually. Furthermore, a significant percentage of veterinary patients with movement limitations could be grossly categorized as geriatric and living within the end stage of their predicted lifespans. Because mobility is correlated to quality of life and time to death in aging dogs, a major goal in optimizing canine geriatric health is to improve functional movement. Within the geriatric population, identifying disabilities that affect daily living and quality of life may be used by the rehabilitation practitioner to provide stronger prognoses, treatment goals, and outcome measures. Examples of such means are described within this review. In human medicine, the concept of “optimal aging”, or “healthy aging”, has emerged in which inevitable detrimental age-related changes can be minimized or avoided at various levels of physical, mental, emotional, and social health. Both environment and genetics may influence aging. Identifying and improving environmental variables we can control remain a key component in optimizing aging. Furthermore, diagnosing and treating age related comorbidities common to older populations allows for improved quality of life and is often directly or indirectly affecting mobility. Obesity, sarcopenia, and a sedentary lifestyle are a trifecta of age-related morbidity common to both people and dogs. Healthy lifestyle choices including good nutrition and targeted exercise play key roles in reducing this morbidity and improving aging. Disablement models act as essential tools for creating more effective physiotherapy plans in an effort to counter dysfunction and disability. Within these models, functional testing represents a standard and validated means of scoring human geriatric function as well as monitoring response to therapy. Because of the great need in dogs, this review aims to provide a reasonable and testable standardized framework for canine functional scoring. We believe a complete assessment of canine geriatric patients should comprise of identifying environmental variables contributing to health status; diagnosing comorbidities related to disease and aging; and characterizing disability with standardized methods. Only through this process can we construct a comprehensive, reasonable, and targeted rehabilitation plan with appropriate follow up aimed at healthy aging.

Nonsteroidal anti-inflammatory drugs restore immune function to respiratory syncytial virus in geriatric cotton rats (Sigmodon hispidus)

Respiratory syncytial virus (RSV) infection is not only a childhood disease, but also a serious health risk for the elderly. We investigated in cotton rats how age affected viral clearance, immune responses, and whether pharmacological intervention was beneficial. Our results demonstrated that in geriatric animals, virus grew to similar titers, but with delayed clearance, compared to adult animals. After primary infection with RSV, geriatric animals were susceptible to secondary infection and results indicated a defective humoral immune response. Depletion of cytotoxic T lymphocytes (CTL) during primary infection delayed clearance, indicating the necessary role of CTL. Pharmacological intervention through nonsteroidal anti-inflammatory ibuprofen resulted in faster viral clearance and complete protection after immunization. In addition, the CTL response in the presence of ibuprofen seemed to be restored. It appears that in geriatric animals, immune functions are not as effective as in adult animals and that anti-inflammatory therapy may restore effective immune function.

Mechanical properties of the different rotator cuff tendons in the rat are similarly and adversely affected by age

Rotator cuff tendon tears and tendinopathies are common injuries affecting a large portion of the population and can result in pain and joint dysfunction. Incidence of rotator cuff tears significantly increases with advancing age, and up to 90% of these tears involve the supraspinatus. Previous literature has shown that aging can lead to inferior mechanics, altered composition, and changes in structural properties of the supraspinatus. However, there is little known about changes in supraspinatus mechanical properties in context of other rotator cuff tendons. Alterations in tendon mechanical properties may indicate damage and an increased risk of rupture, and thus, the purpose of this study was to use a rat model to define age-related alterations in rotator cuff tendon mechanics to determine why the supraspinatus is more susceptible to tears due to aging than the infraspinatus, subscapularis, and teres minor. Fatigue, viscoelastic, and quasi-static properties were evaluated in juvenile, adult, aged, and geriatric rats. Aging ubiquitously and adversely affected all rotator cuff tendons tested, particularly leading to increased stiffness, decreased stress relaxation, and decreased fatigue secant and tangent moduli in geriatric animals, suggesting a common intrinsic mechanism due to aging in all rotator cuff tendons. This study demonstrates that aging has a significant effect on rotator cuff tendon mechanical properties, though the supraspinatus was not preferentially affected. Thus, we are unable to attribute the aging-associated increase in supraspinatus tears to its mechanical response alone.

Anaesthesia of the patient with chronic kidney disease

Chronic kidney disease is common, particularly in geriatric animals. General anaesthesia is usually required for routine procedures (dental prophylaxis, ovariohysterectomy or castration) and emergency procedures, which may have profound effects on the body, especially on cardiac output, subsequent blood pressure and on the perfusion of different vital organs. It is essential to understand the effects of renal dysfunction on the patient, as well as the effects that anaesthesia and surgery may have on the kidneys. The understanding of renal physiology, along with the effect of drug choices, is key to successful management of chronic renal failure.

Bilateral pyelonephritis due to Escherichia coli infection in a captive jaguar (Panthera onca)

ABSTRACT: Extraintestinal pathogenic Escherichia coli (ExPEC) is a highly diverse pathotype of E. coli which colonizes the intestine, and it is considered an important etiological agent associated with bacteremia and other systemic infections, among them urinary tract infection. Retrospective studies evaluating morbidity and mortality of nondomestic felids have demonstrated that urinary tract diseases are among the main causes of death for geriatric animals. Also, mesenchymal neoplasms of the uterus are common in wild felids, and they possess variable morphologic characteristics related to invasiveness and malignancy. This report describes a case of bilateral pyelonephritis due to extraintestinal uropathogenic E. coli infection in a captive jaguar (Panthera onca). The diagnosis was confirmed through pathological, bacterial and immunohistochemical findings. According to molecular analysis, this E. coli strain was classified in the phylogroup F, possessing the following virulence-associated genes: usp, cnf-1, hlyA, papC and sfa. Additionally, this E. coli was highly resistant to β-lactams and first-generation cephalosporin. This jaguar also presented a uterine leiomyoma with distinct distribution, and severe degenerative articular disease, both of them described as frequently seen lesions in geriatric animals from the Panthera genus.

The aging common marmoset's immune system: From junior to senior.

The social, health, and economic challenges of a steadily increasing aging population demand the use of appropriate translational animal models to address questions like healthy aging, vaccination strategies, or potential interventions during the aging process. Due to their genetic proximity to humans, especially nonhuman primates (NHPs) with a relatively short generation period compared to humans, qualify as excellent animal models for these purposes. The use of common marmosets (Callithrix jacchus) in gerontology research steadily increased over the last decades, yet important information about their aging parameters are still missing. We therefore aimed to characterize their aging immune system by comprehensive flow cytometric phenotyping of blood immune cells from juvenile, adult, aging, and geriatric animals. Aged and geriatric animals displayed clear signs of immunosenescence. A decline in CD4/CD8 ratio, increased expression of HLA-DR and PD-1, higher frequencies of CD95+ memory cells, alterations in cytokine secretion, and a decline in the proliferative capacity proved T cell senescence in aging marmosets. Also, the B cell compartment was affected by age-related changes: while overall B cell numbers remained stable with advancing age, expression of the activation marker CD80 increased and immunoglobulin M expression decreased. Interestingly, marmoset B cell memory subset distribution rather mirrored the human situation than that of other NHP. CD21+ CD27- naïve B cell frequencies decreased while those of CD21- CD27- tissue memory B cells increased with age. Furthermore, frequencies and numbers of NK cells as part of the innate immune system declined with advancing age. Thus, the observed immunological changes in common marmosets over their life span revealed several similarities to age-related changes in humans and encourages further studies to strengthen the common marmoset as a potential aging model.

The implementation and initial evaluation of a physical therapy program for captive chimpanzees (Pan troglodytes).

Due to advances in captive nonhuman primate (NHP) medical care, the number of geriatric chimpanzees (≥35-years old) is growing. With old age comes a variety of physical conditions, including arthritis, stroke, and mobility impairments. Programs aimed at enhancing the welfare of geriatric chimpanzees are now quite common, but there are few published empirical evaluations of the efficacy of such programs. The current study aimed to create, implement, and evaluate the effects of participation in a physical therapy (PT) program on physical health, mobility, welfare, and behavior. Nine chimpanzees with mobility impairments participated in personalized PT routines (using positive reinforcement training) twice per week for 5 months. Additionally, nine control chimpanzees (non-mobility-impaired, matched with PT chimpanzees on age and gender) participated in body exam behavior sessions (also using positive reinforcement training) twice per week. All chimpanzees were rated on 14 health, well-being, and behavior items, as well as level of mobility throughout the PT program. Chimpanzees that participated in the PT program showed significant increases in ratings of physical health, well-being, and activity levels across phases of the program. Furthermore, compared to control chimpanzees, PT chimpanzees showed significant increases in ratings of ease of movement. Because raters were not blind to physical therapy treatment, our results represent an initial evaluation of the program that may suggest that participation in the PT program has physical, behavioral, and welfare benefits. Assessments of novel geriatric-focused care strategies and programs are essential to further enhance the welfare of the captive chimpanzee population, which is currently comprised of many geriatric animals, whose proportion of the captive population will only increase.

Age-related changes in sound onset and offset intensity coding in auditory cortical fields A1 and CL of rhesus macaques.

Inhibition plays a key role in shaping sensory processing in the central auditory system and has been implicated in sculpting receptive field properties such as sound intensity coding and also in shaping temporal patterns of neuronal firing such as onset- or offset-evoked responses. There is substantial evidence supporting a decrease in inhibition throughout the ascending auditory pathway in geriatric animals. We therefore examined intensity coding of onset (ON) and offset (OFF) responses in auditory cortex of aged and young monkeys. A large proportion of cells in the primary auditory cortex (A1) and the caudolateral field (CL) displayed nonmonotonic rate-level functions for OFF responses in addition to nonmonotonic coding of ON responses. Aging differentially affected ON and OFF responses; the magnitude of effects was generally greater for ON responses. In addition to higher firing rates, neurons in old monkeys exhibited a significant increase in the proportion of monotonic rate-level functions and had higher best intensities than those in young monkeys. OFF responses in young monkeys displayed a range of intensity coding relationships with ON responses of the same cells, ranging from highly similar to highly dissimilar. Dissimilarity in ON/OFF coding was greater in CL and was reduced with aging, which was largely explained by a preferential decrease in the percentage of cells with nonmonotonic coding of ON and OFF responses. The changes we observed are consistent with previously demonstrated alterations in inhibition in the ascending auditory pathway of primates and could be involved in age-related deficits in the temporal processing of sounds.NEW & NOTEWORTHY Aging has a major impact on intensity coding of neurons in auditory cortex of rhesus macaques. Neural responses to sound onset and offset were affected to different extents, and their rate-level functions became more mutually similar, which could be accounted for by the loss of nonmonotonic intensity coding in geriatric monkeys. These findings were consistent with weakened inhibition in the central auditory system and could contribute to auditory processing deficits in elderly subjects.

The geriatric pain experience in mice: intact cutaneous thresholds but altered responses to tonic and chronic pain

Older individuals have an elevated risk for chronic pain as half of all individuals over 65 years old have at least one chronic pain condition. Unfortunately, relevant assessment tools and recommendations for chronic pain management targeting older adults are lacking. This study explores changes in response to pain between young (2–3 months old) and geriatric (20–24 months old) ages using mice. Although cutaneous thresholds to brisk stimuli (von Frey and radiant heat assays) were not affected, behavioral responses to tonic stimuli (acetone and capsaicin assays) were more pronounced in geriatric animals. After nerve injury, geriatric mice present an altered neuropathic pain profile with hypersensitivity to mechanical stimuli but not acetone and an impairment in conditioned noxious stimuli avoidance. This altered behavioral response pattern was associated with an abnormal monoaminergic signature in the medial prefrontal cortex, suggesting decreased COMT function. We conclude that young and geriatric mice exhibit different behavioral and physiological responses to the experience of pain, suggesting that knowledge and practices must be adjusted for geriatric populations.

Assessment of alterations in biochemical exams indicative of renal and hepatic function concerning sex and in elderly and geriatric dogs - a retrospective study between 2015 and 2017 in Joinville - SC

The population of geriatric animals has grown considerably in the last years, consequently, the number of visits in the veterinary clinical routine of these animals also showed a strong increase. As a useful tool in the diagnosis of diseases or even for the monitoring of animal health, blood tests are aimed at identifying changes that may be a reflection of some pathological process. Within the blood analyzes, the biochemical profile, if correctly interpreted, gives references regarding the clinical state of an animal, as well as its nutritional balance, immunological status, follow-up of treatments and prognoses. Due to the importance of biochemical parameters in the diagnosis of diseases, especially in the geriatric population, the objective of this study was to evaluate the occurrence of alterations in biochemical tests that indicate changes in the renal and hepatic functions of elderly dogs and to classify them in relation to gender and age. For this, biochemical exams were collected in two laboratories in the city and the age of the animals was screened, followed by screenings for liver and kidney alterations and another for sex. The most frequent alteration in the population of geriatric and senior dogs was Alkaline Phosphatase with 50.8% (2.206 / 4.341) and 41.6% (979 / 2.352), respectively. The second analyte with the highest frequency of changes was Urea with 44.2% (1,923 / 4,341) in geriatric dogs and 29.9% (705 / 2.352) in senior dogs. The relevance of sex in relation to age was significant in Alkaline Phosphatase and Urea markers.

Brain parenchymal changes during normal aging in domestic cats

ABSTRACT: This study aimed to identify changes related to brain parenchyma as advancing age in healthy domestic cats. Our hypothesis is that cats suffer cerebral and cerebellar atrophy and show focal changes in signal intensity of the brain parenchyma in accordance with the progression of age. Twelve adult (1 to 6 years), eleven mature (7 to11 years) and ten geriatric non-brachycephalic cats (12 years or more of age) underwent brain magnetic resonance imaging (MRI). There were no changes in signal intensity and contrast uptake in brain parenchyma of the cats. Geriatric animals showed significantly lower average thickness of the interthalamic adhesion and percentage of the cerebral parenchyma volume in relation to intracranial volume than those found in the adult group. No significant differences were found between groups for cerebral volume, cerebellar volume and percentage of cerebellar volume in relation to intracranial volume. The results of this study indicate that atrophy of the cerebral parenchyma, including the interthalamic adhesion, occurs with age in domestic cats, confirming the hypothesis of the study. However, the results did not corroborate the hypothesis that cats show cerebellar atrophy and focal changes in signal intensity of the brain parenchyma with advancing age.

Melatonin as a Therapy for Traumatic Brain Injury: A Review of Published Evidence.

Melatonin (MEL) is a hormone that is produced in the brain and is known to bind to MEL-specific receptors on neuronal membranes in several brain regions. MEL’s documented neuroprotective properties, low toxicity, and ability to cross the blood-brain-barrier have led to its evaluation for patients with traumatic brain injury (TBI), a condition for which there are currently no Food and Drug Administration (FDA)-approved therapies. The purpose of this manuscript is to summarize the evidence surrounding the use of melatonin after TBI, as well as identify existing gaps and future directions. To address this aim, a search of the literature was conducted using Pubmed, Google Scholar, and the Cochrane Database. In total, 239 unique articles were screened, and the 22 preclinical studies that met the a priori inclusion/exclusion criteria were summarized, including the study aims, sample (size, groups, species, strain, sex, age/weight), TBI model, therapeutic details (preparation, dose, route, duration), key findings, and conclusions. The evidence from these 22 studies was analyzed to draw comparisons across studies, identify remaining gaps, and suggest future directions. Taken together, the published evidence suggests that MEL has neuroprotective properties via a number of mechanisms with few toxic effects reported. Notably, available evidence is largely based on data from adult male rats and, to a lesser extent, mice. Few studies collected data beyond a few days of the initial injury, necessitating additional longer-term studies. Other future directions include diversification of samples to include female animals, pediatric and geriatric animals, and transgenic strains.