Parameters of haematology, clinical chemistry and lipid metabolism in the common marmoset and alterations under stress conditions

Hematological and Serum Biochemical Reference Intervals for Alphaxalone Sedated Common Marmosets (Callithrix jacchus)

Marmosets are routinely used in biomedical research, therefore there is an increasing need for updated reference intervals calculated using a large sample size, correct statistics, and considering different variables. Hematological and biochemical values from 472 healthy common marmosets sedated with alphaxalone were collected over a ten-year period (2013-2023). The variables assumed to have influenced the blood-based parameters were compared, i.e., sex, age, housing condition, pregnancy, and contraceptive use. Reference intervals were calculated based on observed percentiles without parametric assumptions, and with parametric assumptions following Box-Cox transformation. Juvenile marmosets showed increased ALP, phosphate, WBC, lymphocyte count, and basophil count and decreased levels of GGT and Fe compared to adults. Marmosets housed strictly indoors showed increased ALT and GGT levels and decreased levels of total bilirubin and neutrophil count compared to marmosets housed with outdoor access. Pregnant marmosets showed increased ALP, total bilirubin, neutrophil count, monocyte count, and basophil count, and decreased levels of AST, ALT, cholesterol, Fe, and lymphocyte count compared to non-pregnant marmosets. Etonogestrel contracepted marmosets showed decreased P-LCR compared to females who were not contracepted. Updated reference intervals will aid researchers and veterinarians in identifying physiological and pathological changes, as well as improve the reproducibility of research in this species.

Quality of hematology and clinical chemistry results in laboratory and zoo nonhuman primates: Effects of the preanalytical phase. A review

Most errors in clinical pathology originate in the preanalytical phase, which includes all steps from the preparation of animals and equipment to the collection of the specimen and its management until analyzed. Blood is the most common specimen collected in nonhuman primates. Other specimens collected include urine, saliva, feces, and hair. The primary concern is the variability of blood hematology and biochemistry results due to sampling conditions with the effects of capture, restraint, and/or anesthesia. Housing and diet have fewer effects, with the exception of food restriction to reduce obesity. There has been less investigation regarding the impact of sampling conditions of nonblood specimens.

Bacterial Cholecystitis and Cholangiohepatitis in Common Marmosets (Callithrix Jacchus)

The common marmoset (Callithrix jacchus), a New World NHP, has emerged as important animal model in multiple areas of translational biomedical research. The quality of translational research in marmosets depends on early diagnosis, treatment, and prevention of their spontaneous diseases. Here, we characterize an outbreak of infectious cholangiohepatitis that affected 7 adult common marmosets in a single building over a 10-mo period. Marmosets presented for acute onset of lethargy, dull mentation, weight loss, dehydration, hyporexia, and hypothermia. Blood chemistries at presentation revealed markedly elevated hepatic and biliary enzymes, but mild neutrophilia was detected in only 1 of the 7. Affected marmosets were unresponsive to rigorous treatment and died or were euthanized within 48 h of presentation. Gross and histopathologic examinations revealed severe, necrosuppurative cholangiohepatitis and proliferative cholecystitis with bacterial colonies and an absence of gallstones. Perimortem and postmortem cultures revealed single or dual isolates of Escherichia coli and Pseudomonas aeruginosa. Other postmortem findings included bile duct hyperplasia, periportal hepatitis, bile peritonitis, ulcerative gastroenteritis, and typhlitis. Environmental contamination of water supply equipment with Pseudomonas spp. was identified as the source of infection, but pathogenesis remains unclear. This type of severe, infectious cholangiohepatitis with proliferative cholecystitis with Pseudomonas spp. had not been reported previously in marmosets, and we identified and here describe several contributing factors in addition to contaminated drinking water.

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.

Immunization with recombinant ORF2 p551 protein protects common marmosets (Callithrix jacchus) against homologous and heterologous hepatitis E virus challenge

BACKGROUND

Hepatitis E virus (HEV) is a major causative agent of acute hepatitis worldwide, prompting continuous HEV vaccine efforts. Vaccine development is hampered by the lack of convenient animal models susceptible to infection with different HEV genotypes. We produced recombinant open reading frame 2 protein (pORF2; p551) of HEV genotype (GT) 3 and assessed its immunogenicity and protectivity against HEV challenge in common marmosets (Callithrix jacchus, CM).

METHODS

p551 with consensus sequence corresponding to amino acid residues 110-660 of HEV GT3 pORF2 was expressed in E. coli and purified by affinity chromatography. CMs were immunized intramuscularly with 20 μg of p551 VLPs with alum adjuvant (n = 4) or adjuvant alone (n = 2) at weeks 0, 3, 7 and 19. At week 27, p551-immunized and control animals were challenged with HEV GT1 or GT3 and thereafter longitudinally screened for markers of liver function, anti-HEV IgG and HEV RNA in feces and sera.

RESULTS

Purified p551 formed VLPs with particle size of 27.71 ± 2.42 nm. Two immunizations with p551 induced anti-HEV IgG mean titer of 1:1810. Immunized CMs challenged with homologous and heterologous HEV genotype did not develop HEV infection during the follow-up. Control CMs infected with both HEV GT1 and GT3 demonstrated signs of HEV infection with virus shedding and elevation of the levels of liver enzymes. High levels of anti-HEV IgG persisted in vaccinated CMs and control CMs that resolved HEV infection, for up to two years post challenge.

CONCLUSIONS

CMs are shown to be a convenient laboratory animal model susceptible to infection with HEV GT1 and GT3. Immunization with HEV GT3 ORF2/p551 triggers potent anti-HEV antibody response protecting CMs from homologous and heterologous HEV challenge. This advances p551 in VLPs as a prototype vaccine against HEV.

Hematology and blood chemistry reference values of free-ranging Callithrix geoffroyi in Urban environment in Espírito Santo state, Brazil

BACKGROUND

The Callithrix geoffroyi are increasingly present in Brazilian urban areas, where they are vulnerable to health problems. The purpose of this study was a description of hematology and nine blood chemistry parameters of free-ranging C. geoffroyi.

METHODS

Thirty individuals were captured in urban-forested settings. The marmosets were anesthetized, venopunctioned, and released shortly after recovery. The analysis was carried on in a veterinary laboratory, using automatic cells counter, staining methods, and an automatic biochemical analyzer.

RESULTS AND CONCLUSIONS

Male and female free-ranging C. geoffroyi have similar hematological and blood chemistry values. The adults presented higher concentrations of erythrocytes (P <.02) and hemoglobin (P <.02) than young marmosets. The platelet concentration was lower (P <.05) in adults comparing to young marmosets. There were not statistically significant differences between young and adult blood chemistry concentrations. This is the first time that are presented hematology and blood biochemistry data on free-ranging C. geoffroyi.

Clinical Management of Gastrointestinal Disease in the Common Marmoset (Callithrix jacchus)

Gastrointestinal disease is a frequently encountered problem among captive common marmoset (Callithrix jacchus) colonies. Management can be challenging due to the number of etiologies responsible for gastrointestinal disease in this species, limitations on diagnostic capabilities, and lack of effective treatments. Understanding commonly described GI diseases in the captive marmoset can provide insight on the impact these diseases have on research studies and aid in the development of appropriate management strategies. A review of commonly encountered GI disease processes as well as routinely implicated causes of GI disease in the common marmoset are provided. Current strategies in clinical management of GI disease in the common marmoset, including approaches to colony health, diagnostic testing, and commonly employed treatments are discussed.

The effects of a training program using a phantom to accustom heifers to the automatic milking system

The introduction of heifers into the automatic milking system (AMS) can be associated with considerable stress for both animals and farm employees, as completely inexperienced heifers initially do not independently enter the unknown milking robot. This study investigated whether training heifers on an AMS phantom provides the possibility of preparing heifers for the following lactation at the AMS. For this purpose, 77 Holstein-Friesian heifers were randomly assigned to one of 2 experimental groups: control (CON) or phantom (PHAN). Four weeks before calving, the PHAN group was given free access to the phantom, which was similar to the actual milking robot, so that they could explore it and be positively conditioned by feeding concentrate in the phantom. The heifers of the CON group had no contact with the phantom or the AMS before the first milking at the AMS. The milking frequency per animal per day was recorded, and the proportion of animals that had to be fetched for milking was determined, to evaluate how the animals accepted the AMS after calving. To assess the stress level of the animals before and after introduction into the AMS, fecal cortisol concentrations and rumination times of the animals were measured. Additionally, lactation performance characteristics (milk yield, milk flow, electrical conductivity of milk, and milk composition) were recorded for 77 animals. The animals trained on the phantom showed a higher milking frequency (DIM 7: 2.70 ± 0.14 visits/d) than the control animals (DIM 7: 2.41 ± 0.14 visits/d) between the 4th and 10th day of lactation. In addition, between d 1 and d 5, the proportion of animals that had to be fetched for milking was lower in PHAN (DIM 1: 35.18 ± 4.16%) than in CON (DIM 1: 48.03 ± 4.46%). The PHAN heifers had unexpectedly high fecal cortisol levels (1 wk prepartum: 43.50 ± 0.93 ng/g of feces), although not considerably elevated compared with CON (1 wk prepartum: 40.76 ± 1.05 ng/g of feces). Training on the phantom had no appreciable influence on rumination time and lactation performance parameters. The increased number of milking visits and the reduced proportion of animals that had to be fetched into the AMS for milking indicate that training on the phantom prepares the animals well for being milked in the AMS. Therefore, training heifers on the phantom offers the possibility to facilitate the start into early lactation for the animals, providing a valuable contribution to improvement of animal welfare.

Values of plasma total proteins of free-living marmosets (Callithrix jacchus) in an urban forest

BACKGROUND

Callithrix jacchus is a small primate widely used in experimentation, but data on plasma total protein (PTP) values of free-living animals inhabiting its own endemism region are non-existent.

METHODS

Marmosets belonging to two free-living groups were captured for marking and obtaining biological material. The collected blood was centrifuged to obtain the plasma and thus to determine the concentration of PTP.

RESULTS AND CONCLUSIONS

Females and adults had the highest mean PTP. Mean found were higher than other values described for other neotropical primates, and the high PTP values presented by the animals indicate dehydration. Due to the importance of total plasma proteins for health and management, obtaining these values as a reference is relevant for the free-living Callithrix genus and other neotropical primates.

Searching for the Haplorrhine Heterotherm: Field and Laboratory Data of Free-Ranging Tarsiers

The observation of heterothermy in a single suborder (Strepsirrhini) only within the primates is puzzling. Given that the placental-mammal ancestor was likely a heterotherm, we explored the potential for heterothermy in a primate closely related to the Strepsirrhini. Based upon phylogeny, body size and habitat stability since the Late Eocene, we selected western tarsiers (Cephalopachus bancanus) from the island of Borneo. Being the sister clade to Strepsirrhini and basal in Haplorrhini (monkeys and apes), we hypothesized that C. bancanus might have retained the heterothermic capacity observed in several small strepsirrhines. We measured resting metabolic rate, subcutaneous temperature, evaporative water loss and the percentage of heat dissipated through evaporation, at ambient temperatures between 22 and 35°C in fresh-caught wild animals (126.1 ± 2.4 g). We also measured core body temperatures in free-ranging animals. The thermoneutral zone was 25-30°C and the basal metabolic rate was 3.52 ± 0.06 W.kg-1 (0.65 ± 0.01 ml O2.g-1.h-1). There was no evidence of adaptive heterothermy in either the laboratory data or the free-ranging data. Instead, animals appeared to be cold sensitive (Tb ~ 31°C) at the lowest temperatures. We discuss possible reasons for the apparent lack of heterothermy in tarsiers, and identify putative heterotherms within Platyrrhini. We also document our concern for the vulnerability of C. bancanus to future temperature increases associated with global warming.

Translational models for vascular cognitive impairment: a review including larger species

BACKGROUND

Disease models are useful for prospective studies of pathology, identification of molecular and cellular mechanisms, pre-clinical testing of interventions, and validation of clinical biomarkers. Here, we review animal models relevant to vascular cognitive impairment (VCI). A synopsis of each model was initially presented by expert practitioners. Synopses were refined by the authors, and subsequently by the scientific committee of a recent conference (International Conference on Vascular Dementia 2015). Only peer-reviewed sources were cited.

METHODS

We included models that mimic VCI-related brain lesions (white matter hypoperfusion injury, focal ischaemia, cerebral amyloid angiopathy) or reproduce VCI risk factors (old age, hypertension, hyperhomocysteinemia, high-salt/high-fat diet) or reproduce genetic causes of VCI (CADASIL-causing Notch3 mutations).

CONCLUSIONS

We concluded that (1) translational models may reflect a VCI-relevant pathological process, while not fully replicating a human disease spectrum; (2) rodent models of VCI are limited by paucity of white matter; and (3) further translational models, and improved cognitive testing instruments, are required.

A longitudinal analysis of the effects of age on the blood plasma metabolome in the common marmoset, Callithrix jacchus

Primates tend to be long-lived for their size with humans being the longest lived of all primates. There are compelling reasons to understand the underlying age-related processes that shape human lifespan. But the very fact of our long lifespan that makes it so compelling, also makes it especially difficult to study. Thus, in studies of aging, researchers have turned to non-human primate models, including chimpanzees, baboons, and rhesus macaques. More recently, the common marmoset, Callithrix jacchus, has been recognized as a particularly valuable model in studies of aging, given its small size, ease of housing in captivity, and relatively short lifespan. However, little is known about the physiological changes that occur as marmosets age. To begin to fill in this gap, we utilized high sensitivity metabolomics to define the longitudinal biochemical changes associated with age in the common marmoset. We measured 2104 metabolites from blood plasma at three separate time points over a 17-month period, and we completed both a cross-sectional and longitudinal analysis of the metabolome. We discovered hundreds of metabolites associated with age and body weight in both male and female animals. Our longitudinal analysis identified age-associated metabolic pathways that were not found in our cross-sectional analysis. Pathways enriched for age-associated metabolites included tryptophan, nucleotide, and xenobiotic metabolism, suggesting these biochemical pathways might play an important role in the basic mechanisms of aging in primates. Moreover, we found that many metabolic pathways associated with age were sex specific. Our work illustrates the power of longitudinal approaches, even in a short time frame, to discover novel biochemical changes that occur with age.