Validation of the i-STAT and HemoCue systems for the analysis of blood parameters in the bar-headed goose, Anser indicus

Validation of the HemoCue Hb 801 portable haemoglobin analyser for fish blood

Haemoglobin concentration ([Hb]) assessment in fish blood has become a routine parameter to measure the health and welfare status of the animals. The original method (haemoglobincyanide method, best known as the Drabkin method) for measuring Hb in human and animals is not well suited for work outside of a laboratory setting. It is relatively time consuming, contains hazardous cyanide elements, and requires specific laboratory material. As an alternative to the Drabkin method, portable analysers have been developed for human blood, but they need to be first validated for fish blood before being used in experiments. In this study, the performance of the new HemoCue Hb 801 portable haemoglobin analyser was compared to the validated Drabkin method to determine [Hb] in three fish species. Hb readings between the two methods were not different for any of the species tested (rainbow trout, Onchorynchus mykiss, Atlantic wolffish, Anarhichas lupus, and Nile tilapia, Oreochromis niloticus). Therefore, this new portable device can be readily used to measure Hb in fish blood. Unlike the previous model from HemoCue, the Hb 201+, this device does not need an incubation time or a correction factor, representing a major gain of time and precision.

Health status of the red-billed tropicbird (Phaethon aethereus) determined by hematology, biochemistry, blood gases, and physical examination

The red-billed tropicbird, Phaethon aethereus, is a species of seabird native to the Galápagos archipelago, and widely distributed across the neotropics. General health, blood chemistry, and haematology parameters have not been published for this species. Blood analyses were performed on samples drawn from 51 clinically healthy red-billed tropicbirds captured from their burrows at Islote Pitt on San Cristóbal Island in July, 2016 (21) and Daphne Major Island in June, 2017 (30). In the field, a point of care blood analyser (iSTAT) was used to obtain results for HCO3-, pH, pCO2, pO2, TCO2, iCa, Na, K, Cl, Hb, HCT, anion gap, creatinine, glucose and urea nitrogen. Additionally, a portable Lactate PlusTM analyser was used to measure blood lactate, and blood smears were also created in situ. The blood slides were used to estimate leukocyte counts and 100-cell differentials. Alongside these biochemistry and haematology parameters, average heart rate, respiratory rate, body temperature and scaled mass index (calculated from weight and a body measurement) were compared to determine the standard measurements for a healthy individual. The baseline data, and reference intervals reported in this paper are essential to detecting changes in the health of red-billed tropicbirds in the future.

Effects of two alveolar recruitment manoeuvres (sustained inflation and stepwise) followed by positive end-expiratory pressure on cardiac output (measured with lithium dilution), invasive blood pressure and arterial oxygen tension in isoflurane-anaesthetised goats

Alveolar recruitment manoeuvres (ARM) performed during general anaesthesia improve oxygenation; however cardiovascular depression may be observed. The aim of the study was to compare the effects of sustained inflation (SI) and stepwise ARMs on cardiac output (CO), mean arterial blood pressure and arterial oxygen tension (PaO2) in ten mechanically ventilated goats anaesthetised with isoflurane. In the SI ARM, peak inspiratory presure (PIP) was increased to 30 cmH2O and sustained for 20 s. In the stepwise ARM, the PIP was increased by 5 cmH2O each minute for three minutes from 10 to 25 cmH2O. Both ARMs were followed by positive end-expiratory pressure of 5 cmH2O. Paired lithium dilution CO measurements and arterial blood samples were obtained before and after each ARM. The order of the ARM was randomised and each goat was subjected to both techniques. Data was reported as median and interquartile range (IQR). Significance was set at 0.05. The median change in CO (measured by subtracting values after and before ARM) was -0.15 L min-1 (IQR -0.51; 0.03) and - 0.90 L min-1 (IQR -1.69; -0.58) for SI and stepwise ARM respectively (p = 0.04). The median change in PaO2 was 3 kPa (IQR -2.7; 7.6) and 0.4 kPa (IQR -3.4; 5.5) for SI and stepwise ARM respectively (p = 0.03). In conclusion, SI ARM causes less impact on CO and provides a better improvement in PaO2 compared to stepwise ARM in goats.

Population density mediates induced immune response, but not physiological condition in a well-adapted urban bird

Thriving under high population density is considered a major feature of urban exploiter species. Nevertheless, population density appears to be a surprisingly overlooked factor in urban ecology studies. High population numbers observed in urban species might promote pathogen transmission and negatively affect health or condition, thus requiring investments in immunocompetence. The feral pigeon Columba livia domestica is an example of a successful city-dweller, found in great abundance in large cities across the globe. We investigated the effects of population density on induced immune response (phytohaemagglutinin skin test) and body condition (blood haemoglobin concentration and size-corrected body mass) in 120 feral pigeons, captured along population density gradient in Łódź (central Poland). We found that stronger immune response was associated with higher population density, but was not related to physiological condition and physiological stress (heterophil/lymphocyte ratio). Moreover, condition indices were not associated with population density. However, since pigeon population density was highly correlated with the level of habitat urbanization, we cannot exclude that any density-dependent effects may be mediated by habitat variation. Our results indicate that urban environment, via population density, might exert different selective pressures on immunocompetence and body condition in this successful urban exploiter.

Conservation of a flagship species: Health assessment of the pink land iguana, Conolophus marthae

The pink land iguana, Conolophus marthae, is one of four species of iguanas (three terrestrial and one marine) in the Galápagos Islands, and the only one listed as critically endangered by the IUCN. The species can only be found on the north-west slopes of the highest volcano on Isabela Island and was first described to science in 2009. As part of a population telemetry study, a health assessment was authorized by the Galápagos National Park. Wild adult iguanas were captured on Wolf Volcano in September 2019 and April 2021 to record morphological and physiological parameters including body temperature, heart rate, intraocular pressures, tear formation, and infrared iris images. Blood samples were also collected and analyzed. An i-STAT portable blood analyzer was used to obtain values for base excess in the extracellular fluid compartment (BEecf), glucose (Glu), hematocrit (HctPCV), hemoglobin (Hb), ionized calcium (iCa), partial pressure of carbon dioxide (pCO₂), partial pressure of oxygen (pO₂)_, percent oxygen saturation (sO₂%), pH, potassium (K), and sodium (Na). When possible, data were compared to previously published and available data for the other Galápagos iguanas. The results reported here provide baseline values that will be useful in detecting changes in health status among pink land iguanas affected by climate change, invasive species, anthropogenic threats, or natural disturbances. The collected data also provide an invaluable resource for conservation scientists planning to implement conservation strategies, like translocations, that may temporarily alter these baseline values.

Lithium dilution cardiac output measurements in isoflurane-anaesthetised goats: Jugular versus cephalic lithium chloride administration

The administration of lithium chloride (LiCl) for cardiac output (CO) measurement via a peripheral instead of a central vein has been described previously as a valid alternative route in pigs and dogs. The aim of the study was to compare CO measurements after administration of LiCl using two peripheral veins, cephalic or jugular, in goats. Ten adult, female, experimental goats undergoing bilateral stifle arthrotomy were recruited for the study. Paired CO measurements were taken two minutes apart during stable conditions in isoflurane-anaesthetised goats. Forty-two paired CO measurements were taken in total, and the median (range) of paired CO measurement per goat were 4.5 (3-6). The mean (SD) CO using the cephalic and jugular vein for injection of LiCl was 5.28 (1.29) L min^-1 and 5.20 (1.24) L min^-1 respectively. The Bland-Altman analysis showed an acceptable agreement with a mean bias of 1.33% with limits of agreement (LoA) of -18.43 to 21.09%. The percentage of error was 25%. The four-quadrant plot analysis showed a poor agreement (71%) between the two routes. The polar plot showed a poor trending ability. An 86% inclusion rate (18/21 points) was reached with a ± 35° radial sector size. The findings revealed that the agreement between the two routes is not as precise as the authors expected, however the results are comparable with studies published previously.

The high-altitude bird chronicles: lessons from field work with Frapps

Over the past decade, Peter Frappell, aka Frapps, has been an integral part of an international group studying birds that migrate or reside at altitude. This research has taken the extended group from Terkhiin Tsagaan Lake on the Mongolian plateau to Chilika Lake in eastern India, Koonthankulum bird sanctuary in southern India, Lake Qinghai in Chinese Tibet, Summer Lake Wildlife and Malheur National Wildlife Refuge in Oregon, and San Pedro a Marca, Vichaycocha and Lake Titicaca National Reserve in Perú. It has been a productive project producing over 30 manuscripts, 15 of which were based on research in the field. What has not been published are the stories behind the research and the critical lessons learned along the way. Some of these are chronicled here.

Comprehensive health assessment and blood analyte reference intervals of gopher tortoises (Gopherus polyphemus) in southeastern FL, USA

The gopher tortoise (Gopherus polyphemus), a keystone species, is declining throughout its geographic range. Lack of knowledge with respect to the potential infectious diseases present within wild populations creates a dilemma for wildlife biologists, conservationists and public policy makers. The objective of this study was to conduct a health assessment of two previously unstudied gopher tortoise aggregations located at two sites in southeastern FL. Samples were collected from 91 tortoises (48 adults, 35 juveniles, 8 hatchlings) captured at Florida Atlantic University's Harbor Branch Oceanographic Institute, in Fort Pierce, FL, USA in 2019, and Loggerhead Park in Juno Beach, FL, USA, during 2018-2019. Samples of blood, nasal swabs and oral/cloacal swabs were analyzed for hematology, plasma protein electrophoretic profiles and infectious disease testing including Mycoplasma spp. serology and polymerase chain reaction (PCR) assays for Ranavirus, Herpesvirus and Anaplasma spp. Hematological and plasma protein electrophoresis reference intervals are presented for adult and juvenile tortoises from both sites combined. Clinical signs consistent with upper respiratory tract disease (URTD) were observed in 18/91 (20%) tortoises, and antibodies to Mycoplasma agassizii were detected in 33/77 (42.9%) tortoises. Adult tortoises were significantly more likely than juveniles to have URTD clinical signs, and statistically significant, positive relationships were observed between the presence of antibodies to Mycoplasma spp. and carapace length, packed cell volume and plasma globulin concentrations. Anaplasma spp. inclusions were observed in 8/82 (10%) tortoises, but PCR detected Anaplasma sp. in 21/83 (25%) tortoises. Herpesvirus and Ranavirus were not detected in any blood or swab samples. This work contributes important baseline information on the health of gopher tortoises toward the southern end of the species' range.

Baseline haematology, biochemistry, blood gas values and health status of the Galapagos swallow-tailed gull (Creagrus furcatus)

The swallow-tailed gull, Creagrus furcatus, is a seabird endemic to the Galápagos archipelago. In general health, blood chemistry and haematology, parameters have not been published for this species. Blood analyses were run on samples drawn from 58 clinically healthy swallow-tailed gulls captured at Islote Pitt on San Cristóbal Island in July 2016 (28) and South Plaza Island in June 2017 (30). A point of care blood analyzer (iSTAT) was used in the field to obtain results for HCO₃ ^-, pH, pCO₂, pO₂, TCO₂, anion gap, chloride, creatinine, glucose, haematocrit, haemoglobin, ionized calcium, potassium, sodium and urea nitrogen. A portable Lactate Plus™ analyzer was used to measure lactate. The baseline data reported is valuable for comparisons amongst different populations in the archipelago and to detect changes in health status of Galápagos swallow-tailed gulls.

Comprehensive health assessment of green turtles Chelonia mydas nesting in southeastern Florida, USA

Important indicators of population health needed for large-scale sea turtle population recovery efforts include demographics, disease and mortality trends, condition indices, and baseline blood data. With this comprehensive health assessment of adult female green sea turtles Chelonia mydas nesting on Juno Beach, Florida, USA, we (1) established comprehensive baseline health indices; (2) identified individuals with evidence of infection by chelonid alphaherpesviruses 5 and 6 (ChHV5, ChHV6), which are implicated in fibropapillomatosis and respiratory and skin disease, respectively; and (3) compared measured health indices between turtles that did versus those that did not test positive for ChHV5 and/or ChHV6. All 60 turtles included in the study were in good body condition with no external fibropapillomatosis tumors. Hematological and biochemical reference intervals were established. Via quantitative PCR (qPCR), 5/60 turtles (8%) tested positive for ChHV5, and all turtles were negative for ChHV6. Of 41 turtles tested for antibodies to ChHV5 and ChHV6, 29% and 15% tested positive, respectively, and 10% tested positive for antibodies to both viruses. Notably, there were no statistically significant differences between health variables for nesting turtles that tested positive for ChHV5 DNA versus those that tested negative; and also no differences between turtles that tested positive for ChHV5 or ChHV6 antibodies and those that did not. This suggests that these viruses are enzootically stable in Florida’s adult green turtles. This study provides a health profile of nesting green turtles in southeastern Florida applicable to temporal and spatial investigations of this and other populations.

Point-of-care testing for measuring haemolymph glucose in invertebrates is not a valid method

Blood glucose is widely used as a physiological parameter for vertebrates and invertebrates. However, its measurement in the field is often difficult due to the need for expensive and non-portable equipment. Point-of-care (POC) devices, originally intended for human use, are increasingly being used for measuring blood parameters of animals in the field. In this regard, POC glucose meters are becoming valuable tools for conservation physiologists, as glucose can be a useful indicator of stress response. In invertebrates, the use of POC glucose meters is still scarce, and no study yet has evaluated their usability in crustaceans and molluscs. We tested if a POC device can be used to measure haemolymph glucose in two widely used models, Leptuca thayeri and Perna perna, compared with a standard laboratory method. The device was unable to measure glucose in P. perna haemolymph due to equipment inaccuracy and low glucose concentration in this species (10.13 ± 6.25 mg/dL). Additionally, despite the device being capable of measuring glucose in L. thayeri haemolymph, Bland-Altman plots showed a strong bias and wide limits of agreement, and Lin's concordance correlation coefficient showed a weak concordance between methods. When simulating experimental conditions, POC results differed from those found using the standard method. We conclude that POC glucose meters are unsuitable for assessing glucose in mussels and should not be used in crabs as results are inaccurate.

Effects of External Oiling and Rehabilitation on Hematological, Biochemical, and Blood Gas Analytes in Ring-Billed Gulls (Larus delawarensis)

Avian species experience extensive morbidity and mortality following large-scale oil spills, often resulting in oiled birds being rescued, and admitted to rehabilitation. Our objective was to experimentally establish time-specific, descriptive blood analyte data following sublethal oil exposure and subsequent rehabilitation. Thirty wild Ring-billed Gulls (Larus delawarensis) were randomly allocated to three treatment groups of 10 birds each. One treatment group served as controls and two treatment groups were externally oiled daily for 3 days with weathered MC252 oil collected from the Deepwater Horizon oil spill, mimicking the upper threshold of the US Fish and Wildlife Service's moderate oiling classification. Following external oiling, one oiled treatment group was cleaned via standard rehabilitation practices. Serial venous blood samples were collected for a month to measure packed cell volume, total solids, blood gas and select plasma biochemistry analytes, total white blood cell estimates and differentials, and reticulocyte estimates. We found that both sublethal oil exposure and aspects of captivity were associated with a mild non-regenerative anemia. No other differences in venous blood gas and biochemical analytes as well as white blood cell concentrations were observed among the three groups. These findings suggest that the mild anemia seen in oiled birds undergoing rehabilitation is possibly multifactorial and that moderately oiled gulls have subtle, but potentially not insignificant clinicopathological abnormalities following sublethal oil exposure. Oiled gulls did not develop any clinicopathological derangements post-rehabilitation, suggesting current standard practices for rehabilitation cause minimal morbidity in clinically stable, moderately oiled gulls.

Health assessment of Conolophus subcristatus, Conolophus pallidus, and C. subcristatus X Amblyrhynchus cristatus hybrid (Galápagos land iguanas)

The land iguanas, Conolophus pallidus and Conolophus subcristatu are large and charismatic lizards endemic to the Galápagos archipelago, but little information exists on their normal health parameters. The former is restricted to Santa Fe island, while C. subcristatus inhabits the islands of the central and western region of the archipelago. Both species are classified as vulnerable by the IUCN Red List of Threatened Species. As part of a population health assessment authorized by the Galápagos National Park, wild adult iguanas from three islands (North Seymour, South Plazas, and Santa Fe) were captured in July 2018. Data from a single C. subcristatus X Amblyrhynchus cristatus hybrid captured on South Plazas is also included. We analyzed blood samples drawn from 52 healthy wild adult land iguanas captured on three islands. An iSTAT portable blood analyzer was used to obtain values for pH, lactate, pO2, pCO2, HCO3-, sO2%, hematocrit, packed cell volume (PCV), hemoglobin Na, K, iCa, and glucose. Standard laboratory hematology techniques were employed for PCV determination; resulting values were also compared to the hematocrit values generated by the iSTAT. Body temperature, heart rate, respiratory rate, and body measurements were also recorded and compared to previously published data for the marine iguana (Amblyrhynchus cristatus), which shares a common ancestor with the land iguana. The data reported here provide preliminary baseline values that may be useful in comparisons between captive and wild populations, between wild populations, and in detecting changes in health status among Galápagos land iguanas affected by anthropogenic threats, climate change, or natural disturbances.

Plasma chemistry in nesting leatherback sea turtles (Dermochelys coriacea) from Florida: Understanding the importance of sample hemolysis effects on blood analytes

Plasma chemistry is widely used in diagnostic and research settings in sea turtles. However, plasma discolorations such as hemolysis are often not considered in data interpretation. The objectives of this study were to (1) evaluate the effects of moderate hemolysis on plasma electrolytes, minerals, and proteins using dry chemistry analysis (DCA) and protein electrophoresis from nesting leatherback sea turtles (Dermochelys coriacea) from Florida and to (2) establish blood analyte reference intervals. Twenty-six plasma samples with absence of hemolysis were selected and sub-divided into one non-hemolytic aliquot and an aliquot that was experimentally manipulated to mimic moderate hemolysis. Plasma samples were analyzed for hemoglobin using a handheld photometer; sodium, potassium, chloride, magnesium, calcium, phosphorus, and total protein using DCA; and protein electrophoresis. Packed cell volume and hemoglobin were measured in corresponding whole blood samples. Reference intervals were established. All analytes except calcium and pre-albumin were significantly higher and the calcium:phosphorus and albumin:globulin ratios were significantly lower in hemolytic plasma compared to non-hemolytic plasma. Alpha2-globulins and potassium were the analytes most impacted by hemolysis, averaging 3.3- and 2.0-fold higher in hemolyzed samples, respectively, indicating that (1) hemoglobin migrates into the alpha2-globulin region in this species and (2) notable intracellular potassium is released into plasma with hemolysis. Attempted conversion factors for compensation of hemolysis were considered inaccurate for 4 of 16 analytes due to non-significant regression lines. We also report that PCV provides an estimate of hemoglobin (g/L) using the formula: (2.59 × PCV) + 24.59. Given the spurious effects of hemolysis, the degree of this artifact should be reported with biochemistry data, and samples with moderate to severe hemolysis should be excluded from datasets when interpreting electrolyte, mineral, and protein results. This will ensure accurate data interpretation for individual turtles in rehabilitation or research settings and population-level data relevant to conservation-focused projects.

Physiological condition of nestling great tits (Parus major) declines with the date of brood initiation: a long term study of first clutches

In seasonal environments, a temporal decline in breeding performance (e.g. clutch size, nestling condition, and fledging success) of altricial bird species is a well-known phenomenon. In this study, we present the effect of laying phenology on the physiological condition of nestling great tits (Parus major) in 14 consecutive breeding seasons. We used blood haemoglobin and baseline glucose concentrations as indicators of nestling physiological condition. Nestling blood haemoglobin reflects food base quality and availability during the breeding period. Blood glucose concentration can be used as a supplementary reverse index of condition, since it is negatively related to environmental quality. It might be indicative of the stress caused by unfavourable extrinsic factors, though, due to potential confounding factors such as adverse weather conditions, low food quality, or feeding interruptions, glucose levels should be used in this ecological context with caution. Great tit nestlings from earlier broods were characterised by higher mean haemoglobin concentrations, indicating a seasonal decline in food quality and availability. The blood glucose concentration displayed an opposite pattern, with nestlings from earlier broods being characterised by lower mean concentrations than those from later broods. However, very little of the variation in blood glucose concentration can be explained by the variation in laying date, which suggests that blood glucose concentration is of little importance in the context of breeding phenology. Our results show that the physiological condition of nestlings of this species decreases as the breeding season progresses, most probably due to environmental factors.

Health Status of Great Frigatebirds (Fregata minor) Determined by Haematology, Biochemistry, Blood Gases, and Physical Examination

The great frigatebird, Fregata minor, is a widely distributed seabird native to the Galápagos archipelago. Haematology and blood chemistry parameters have been published for this species but not from the San Cristóbal and North Seymour great frigatebird breeding colonies. Analyses were run on blood samples drawn from 25 great frigatebirds captured by hand at their nests at Punta Pitt on San Cristóbal Island and 30 birds on North Seymour Island, Galápagos Islands. A portable blood analyser (iSTAT) was used to obtain near immediate field results for pH, pO₂, pCO₂, TCO₂, HCO_3^- , haematocrit (Hct), haemoglobin (Hb), sodium (Na), potassium (K), chloride (Cl), ionized calcium (iCa), creatinine, urea nitrogen, anion gap and glucose. Blood lactate was measured using a portable Lactate Plus™ analyser. Average heart rate, respiratory rate, body weight, body temperature, biochemistry and haematology parameters were comparable to healthy individuals of other Fregatidae. The reported results provide baseline data that can be used for comparisons among populations and in detecting changes in health status among Galápagos great frigatebirds.

Divergent respiratory and cardiovascular responses to hypoxia in bar-headed geese and Andean birds

Many high-altitude vertebrates have evolved increased capacities in their oxygen transport cascade (ventilation, pulmonary diffusion, circulation and tissue diffusion), enhancing oxygen transfer from the atmosphere to mitochondria. However, the extent of interspecies variation in the control processes that dictate hypoxia responses remains largely unknown. We compared the metabolic, cardiovascular and respiratory responses to progressive decreases in inspired oxygen levels of bar-headed geese (Anser indicus), birds that biannually migrate across the Himalayan mountains, with those of Andean geese (Chloephaga melanoptera) and crested ducks (Lophonetta specularioides), lifelong residents of the high Andes. We show that Andean geese and crested ducks have evolved fundamentally different mechanisms for maintaining oxygen supply during low oxygen (hypoxia) from those of bar-headed geese. Bar-headed geese respond to hypoxia with robust increases in ventilation and heart rate, whereas Andean species increase lung oxygen extraction and cardiac stroke volume. We propose that transient high-altitude performance has favoured the evolution of robust convective oxygen transport recruitment in hypoxia, whereas life-long high-altitude residency has favoured the evolution of structural enhancements to the lungs and heart that increase lung diffusion and stroke volume.

Altitude matters: differences in cardiovascular and respiratory responses to hypoxia in bar-headed geese reared at high and low altitudes

Bar-headed geese (Anser indicus) fly at high altitudes during their migration across the Himalayas and Tibetan plateau. However, we know relatively little about whether rearing at high altitude (i.e. phenotypic plasticity) facilitates this impressive feat because most of what is known about their physiology comes from studies performed at sea level. To provide this information, a comprehensive analysis of metabolic, cardiovascular and ventilatory responses to progressive decreases in the equivalent fractional composition of inspired oxygen (FiO2: 0.21, 0.12, 0.09, 0.07 and 0.05) was made on bar-headed geese reared at either high altitude (3200 m) or low altitude (0 m) and on barnacle geese (Branta leucopsis), a low-altitude migrating species, reared at low altitude (0 m). Bar-headed geese reared at high altitude exhibited lower metabolic rates and a modestly increased hypoxic ventilatory response compared with low-altitude-reared bar-headed geese. Although the in vivo oxygen equilibrium curves and blood-oxygen carrying capacity did not differ between the two bar-headed goose study groups, the blood-oxygen carrying capacity was higher than that of barnacle geese. Resting cardiac output also did not differ between groups and increased at least twofold during progressive hypoxia, initially as a result of increases in stroke volume. However, cardiac output increased at a higher FiO2 threshold in bar-headed geese raised at high altitude. Thus, bar-headed geese reared at high altitude exhibited a reduced oxygen demand at rest and a modest but significant increase in oxygen uptake and delivery during progressive hypoxia compared with bar-headed geese reared at low altitude.

Point-of-care devices for physiological measurements in field conditions. A smorgasbord of instruments and validation procedures

Point-of-care (POC) devices provide quick diagnostic results that increase the efficiency of patient care. Many POC devices are currently available to measure metabolites, blood gases, hormones, disease biomarkers or pathogens in samples as diverse as blood, urine, feces or exhaled breath. This diversity is potentially very useful for the comparative physiologist in field studies if proper validation studies are carried out to justify the accuracy of the devices in non-human species under different conditions. Our review presents an account of physiological parameters that can be monitored with POC devices and surveys the literature for suitable quantitative and statistical procedures for comparing POC measurements with reference "gold standard" procedures. We provide a set of quantitative tools and report on different correlation coefficients (Lin's Concordance Correlation Coefficient or the more widespread Pearson correlation coefficient), describe the graphical assessment of variation using Bland-Altman plots and discuss the difference between Model I and Model II regression procedures. We also report on three validation datasets for lactate, glucose and hemoglobin measurements in birds using the newly proposed procedures. We conclude the review with a haphazard account of future developments in the field, emphasizing the interest in lab-on-a-chip devices to carry out more complex experimental measurements than the ones currently available in POC devices.

Calibration of the HemoCue point-of-care analyser for determining haemoglobin concentration in a lizard and a fish

Haemoglobin concentration ([Hb]) is measured for a wide variety of animal studies. The use of point-of-care devices, such as the HemoCue, is becoming increasingly common because of their portability, relative ease of use and low cost. In this study, we aimed to determine whether the [Hb] of blue-tongued skink (Tiliqua nigrolutea) blood can be determined accurately using the HemoCue and whether the HemoCue overestimates the [Hb] of reptile blood in a similar manner to fish blood. Additionally, we aimed to test whether ploidy affected [Hb] determined by the HemoCue using blood from diploid and triploid Atlantic salmon (Salmo salar). The HemoCue Hb 201(+) systematically overestimated [Hb] in both blue-tongued skinks and Atlantic salmon, and there was no difference between calibration equations determined for diploid or triploid salmon. The overestimation was systematic in both species and, as such, [Hb] determined by the HemoCue can be corrected using appropriate calibration equations.

Evaluating the effect of sample type on American alligator (Alligator mississippiensis) analyte values in a point-of-care blood analyser

The assessment of wildlife health has been enhanced by the ability of point-of-care (POC) blood analysers to provide biochemical analyses of non-domesticated animals in the field. However, environmental limitations (e.g. temperature, atmospheric humidity and rain) and lack of reference values may inhibit researchers from using such a device with certain wildlife species. Evaluating the use of alternative sample types, such as plasma, in a POC device may afford researchers the opportunity to delay sample analysis and the ability to use banked samples. In this study, we examined fresh whole blood, fresh plasma and frozen plasma (sample type) pH, partial pressure of carbon dioxide (PCO2), bicarbonate (HCO3 (-)), total carbon dioxide (TCO2), base excess (BE), partial pressure of oxygen (PO2), oxygen saturation (sO2) and lactate concentrations in 23 juvenile American alligators (Alligator mississippiensis) using an i-STAT CG4+ cartridge. Our results indicate that sample type had no effect on lactate concentration values (F 2,65 = 0.37, P = 0.963), suggesting that the i-STAT analyser can be used reliably to quantify lactate concentrations in fresh and frozen plasma samples. In contrast, the other seven blood parameters measured by the CG4+ cartridge were significantly affected by sample type. Lastly, we were able to collect blood samples from all alligators within 2 min of capture to establish preliminary reference ranges for juvenile alligators based on values obtained using fresh whole blood.