Blood gases, biochemistry and haematology of Galápagos hawksbill turtles (Eretmochelys imbricata)

Comparative plasma biochemistry analyte data in nesting leatherback (Dermochelys coriacea), foraging green (Chelonia mydas) and foraging and nesting hawksbill (Eretmochelys imbricata) sea turtles in Grenada, West Indies

Blood biochemistry represents a minimally invasive tool for monitoring sea turtle health, assessing injured sea turtles and supporting conservation strategies. In Grenada, West Indies, plasma biochemical variables were examined in 33 nesting leatherback (Dermochelys coriacea), 49 foraging green (Chelonia mydas), 49 foraging hawksbill (Eretmochelys imbricata) and 12 nesting hawksbill sea turtles sampled between 2017 and 2022. Plasma biochemistry reference intervals are described herein except for nesting hawksbills, which are represented by descriptive statistics due to the low sample size. Select analyte concentrations were positively correlated with curved carapace length in leatherbacks (chloride), green turtles (total protein, albumin and globulin) and foraging hawksbills (total protein, albumin and phosphorus). Cholesterol (7.8 mmol/l ± 1.6 SD) and triglyceride (6.9 mmol/l ± 1.9 SD) concentrations were significantly higher in leatherbacks compared to foraging green turtles, foraging hawksbills and nesting hawksbills (P < 0.001 for all). Cholesterol was significantly higher in nesting hawksbills compared to foraging green turtles (P = 0.050) and foraging hawksbills (P = 0.050). Foraging hawksbills demonstrated significantly higher aspartate transaminase activities than leatherbacks (P = 0.002), green turtles (P = 0.009) and nesting hawksbills (P < 0.001). Biochemical results provide baseline population health data and support guidance for treatments during clinical sea turtle rehabilitation efforts. They also provide insight into species-specific physiologic differences and preludes further studies to better characterize the impacts of life-stage class on biochemistry reference intervals to better support wild sea turtle populations in Grenada.

Blood chemistry and biliverdin differ according to reproduction and tourism in a free-living lizard

Changes in the physiological health of species are an essential indicator of changing conditions and environmental challenges. Reponses to environmental challenges can often induce stress, influence physiology, and change metabolism in organisms. Here we tested blood chemistry parameters indicative of stress and metabolic activity using an i-STAT point-of-care blood analyzer in seven populations of free-ranging rock iguanas exposed to varying levels of tourism and supplemental feeding. We found significant differences in blood chemistry (glucose, oxygen, carbon dioxide, hematocrit, hemoglobin, calcium, potassium, and biliverdin levels) among populations exposed to varying levels of tourism, and some variation between sexes and reproductive states. However, different variables are not directly related to one another, suggesting that the causal physiological pathways driving tourism-induced differences are influenced by mechanisms that are not detected by common analyses of blood chemistry. Future work should investigate upstream regulators of these factors affected by tourism. Regardless, these blood metrics are known to be both stress sensitive and related to metabolic activity, suggesting that exposure to tourism and associated supplemental feeding by tourists are generally driven by stress-related changes in blood chemistry, biliverdin, and metabolism.

HEMATOLOGIC AND BIOCHEMICAL VALUES OF FREE-RANGING HAWKSBILL SEA TURTLES (ERETMOCHELYS IMBRICATA) IN GLOVER'S REEF, BELIZE

Blood samples were obtained from the dorsal cervical sinus of free-ranging hawksbill sea turtles (Eretmochelys imbricata) collected at Glover's Reef Marine Reserve, 42 km east of the coast of Belize, for hematology and plasma biochemistry analysis. Unknown sex, subadult turtles (N = 32) were sampled in 2013 (n = 22) and 2017 (n = 10). To provide a more robust data set, parameters that did not have statistically significant differences were pooled and treated as a single population. Eleven hematologic parameters were evaluated; of these, five were pooled. Twenty-three plasma biochemical parameters were evaluated; of these, 15 were pooled. The PCV observed in this study (mean 33.44%) was double that observed in two studies of juvenile hawksbills in Dubai (means 17% and 16%), whereas the total WBC count was half that observed in immature and adult hawksbills sampled in the Galápagos (mean 2.91 × 10³ versus 5.3 × 103/µl). Total protein and albumin were lower than regionally similar, adult female hawksbills in Brazil (means 3.36 versus 5.45 g/dl and 0.93 versus 2.11 g/dl, respectively). Globulins were higher (mean 2.43 versus 1.06 and 0.5 g/dl), driving the albumin:globulin ratio lower than that observed in two studies of juvenile hawksbills in Dubai (0.4:1 versus 1.1:1 and 1:1, respectively). These findings represent a geographically distinct population from previous reports, highlight the variability in blood parameters from disparate populations, and reaffirm the vital importance of considering a multitude of variables when interpreting reptilian blood values. The similarities in the majority of values observed in 2013 and 2017 provide confidence in the stability of these parameters in this population.

Haematological and biochemical reference intervals for wild green turtles (Chelonia mydas): a Bayesian approach for small sample sizes

Animal health is directly linked to population viability, which may be impacted by anthropogenic disturbances and diseases. Reference intervals (RIs) for haematology and blood biochemistry are essential tools for the assessment of animal health. However, establishing and interpreting robust RIs for threatened species is often challenged by small sample sizes. Bayesian predictive modelling is well suited to sample size limitations, accounting for individual variation and interactions between influencing variables. We aimed to derive baseline RIs for green turtles (Chelonia mydas) across two foraging aggregations in North Queensland, Australia, using Bayesian generalized linear mixed-effects models (n = 97). The predicted RIs were contained within previously published values and had narrower credible intervals. Most analytes did not vary significantly with foraging ground (76%, 22/29), body mass (86%, 25/29) or curved carapace length (83%, 24/29). Length and body mass effects were found for eosinophils, heterophil:lymphocyte ratio, alkaline phosphatase, aspartate transaminase and urea. Significant differences between foraging grounds were found for albumin, cholesterol, potassium, total protein, triglycerides, uric acid and calcium:phosphorus ratio. We provide derived RIs for foraging green turtles, which will be helpful in future population health assessments and conservation efforts. Future RI studies on threatened species would benefit from adapting established veterinary and biomedical standards.

Agreement between hematocrits measured with electrical conductivity on the i-STAT analyzer and manual packed cell volume measurements in 148 chelonian patients

BACKGROUND

Point-of-care (POC) analyzers are increasingly used for diagnostic testing in exotic animals. A few studies with small sample sizes, evaluating agreement between hematocrit (Hct) and packed cell volume (PCV) measurements in chelonians, showed conflicting results.

OBJECTIVE

We aimed to assess the agreement between Hct values measured with a POC analyzer and manual PCV measurements in venous samples from 148 chelonians.

METHODS

All chelonians that underwent bloodwork for clinical reasons had Hct measured with an analyzer employing electrical conductivity (i-STAT, Abbott), PCVs measured using centrifugation, and total solids (TS) measured with refractometry. Bland-Altman plots were built to assess agreement between the measurements. Generalized linear mixed models were used to determine the effect of different variables on the difference between Hct and PCV.

RESULTS

Of 192 chelonians sampled during this period, 148 had Hct, PCV, and TS results. Hct significantly underestimated PCV, with a mean difference between the techniques of -3.8% (95% CI: -4.5 to -3.2; LoA: -11.5 to 3.8). There was a negative correlation between the value of TS and the difference between the methods. Controlling for other factors, the magnitude of the disagreement was not affected by the sex of the chelonian but was smaller in red-eared sliders (Trachemys scripta elegans).

CONCLUSIONS

Hct values measured with electrical conductivity in chelonians significantly underestimated manual PCVs by about 4%. This difference should be considered whenever an Hct measured on a POC analyzer using electrical conductance is used in chelonian patient assessments.

Lack of impact of radiation on blood physiology biomarkers of Chernobyl tree frogs

BACKGROUND

Human actions have altered natural ecosystems worldwide. Among the many pollutants released to the environment, ionizing radiation can cause severe damage at different molecular and functional levels. The accident in the Chernobyl Nuclear Power Plant (1986) caused the largest release of ionizing radiation to the environment in human history. Here, we examined the impact of the current exposure to ionizing radiation on blood physiology biomarkers of adult males of the Eastern tree frog (Hyla orientalis) inhabiting within and outside the Chernobyl Exclusion Zone. We measured the levels of eight blood parameters (sodium, potassium, chloride, ionized calcium, total carbon dioxide, glucose, urea nitrogen, and anion gap), physiological markers of homeostasis, as well as of liver and kidney function.

RESULTS

Levels of blood physiology biomarkers did not vary in function of the current exposure of tree frogs to ionizing radiation within the Chernobyl Exclusion Zone. Physiological blood levels were similar in frogs inhabiting Chernobyl (both in areas with medium-high or low radiation) than in tree frogs living outside Chernobyl exposed only to background radiation levels.

CONCLUSIONS

The observed lack of effects of current radiation levels on blood biomarkers can be a consequence of the low levels of radiation currently experienced by Chernobyl tree frogs, but also to the fact that our sampling was restricted to active breeding males, i.e. potentially healthy adult individuals. Despite the clear absence of effects of current radiation levels on physiological blood parameters in tree frogs, more research covering different life stages and ecological scenarios is still needed to clarify the impact of ionizing radiation on the physiology, ecology, and dynamics of wildlife inhabiting radioactive-contaminated areas.

Blood oxygen stores of olive ridley sea turtles, Lepidochelys olivacea are highly variable among individuals during arribada nesting

Sea turtles dive with a full lung of air and these O₂ stores are supplemented by O₂ stored in blood and muscle. Olive ridley sea turtles exhibit polymorphic nesting behavior, mass nesting behavior called arribada, where thousands of turtles will nest at once, and solitary nesting behavior. The potential physiological differences between the individuals using these strategies are not well understood. We measured blood volume and associated variables, including blood hemoglobin content and hematocrit, to estimate total blood O₂ stores. There were no significant differences in mean values between nesting strategies, but arribada nesting individuals were more variable than those performing solitary nesting. Mass-specific plasma volume was relatively invariant among individuals but mass specific blood volume and blood oxygen stores varied widely, twofold and threefold, respectively. Blood O₂ stores represented 32% of total body O₂ stores. Under typical mean diving conditions of 26 °C and high levels of activity, blood stores confer ~ 14 min to aerobic dive times and are likely critical for the long duration, deep diving exhibited by the species. Individual differences in blood O₂ stores strongly impact estimated aerobic dive limits and may constrain the ability of individuals to respond to changes on ocean climate.

Comparison of Dilution on Eastern Box Turtle (Terrapene carolina carolina) and Marine Toad (Rhinella marinus) Blood Parameters as Measured on a Portable Chemistry Analyzer

Biochemical testing is an important clinical tool in evaluating the physiology of reptiles and amphibians. Suitable point of care analyzers can allow for rapid delivery of results, but small patient size can inhibit sufficient sample collection. This study evaluated the utility of sample dilution with sterile distilled water as a means of biochemical evaluation when sample volume is limited. Blood was collected from 12 eastern box turtles (Terrapene carolina carolina) and 12 marine toads (Rhinella marinus) and analyzed via i-STAT CHEM8+ cartridges. Two undiluted samples and two samples diluted 1 : 1 with sterile water were evaluated immediately following collection for each animal in the study. Analytes reported in the diluted samples were limited to glucose, ionized calcium, and total carbon dioxide. The expected dilution ratio value of diluted to undiluted samples was 0.5, of which glucose in both turtles and toads was nearest. Dilution ratio values for ionized calcium, however, were higher than expected in both turtles and toads. Sample dilution is not recommended for most analytes included on the CHEM8+ cartridge due to values occurring outside the limits of detection for the analyzer. Glucose and ionized calcium values obtained on diluted samples should be interpreted with caution but may provide clinical utility in reptile and amphibian patients where sample volume is limited.

Venous blood gas and biochemical analysis of wild captured green turtles (Chelonia mydas) and Kemp's ridley turtles (Lepidochelys kempii) from the Gulf of Mexico

Blood was collected from wild captured green and Kemp’s ridley turtles off the west coast of Florida, USA. Blood gases and biochemical values were analyzed using a point of care (POC) device in the field. Analytes include pH, partial pressure of carbon dioxide (pCO₂), partial pressure of oxygen (pO₂), total carbon dioxide (TCO₂), bicarbonate (HCO₃), base excess (BE), oxygen saturation (sO₂), lactate, sodium (Na), potassium (K), chloride (Cl), total carbon dioxide (TCO₂), anion gap, ionized calcium, glucose, blood urea nitrogen (BUN), creatinine (Crea), hematocrit (Hct), and hemoglobin (Hb). These are novel data for wild healthy Kemp’s ridley turtles, and results for green turtles were generally consistent with past studies of green turtles with exceptions primarily in blood gas values. Ninety percent of the green turtles had fibropapillomatosis (FP), but none of the blood analytes were correlated with disease severity. Only BUN was correlated with weight of green turtles, and there was no correlation between blood parameters and weight of Kemp’s ridley turtles. This study provides data that are useful in understanding the physiologic status of sea turtles specific to this region, allowing for comparisons to other populations, life stages, and disease states.

Anaesthesia of hatchling green sea turtles (Chelonia mydas) with intramuscular ketamine-medetomidine-tramadol

OBJECTIVE

To characterise intramuscular ketamine-medetomidine-tramadol anaesthesia in hatchling green sea turtles (Chelonia mydas).

STUDY DESIGN

Prospective clinical trial.

ANIMALS

Ten hatchling green sea turtles.

MATERIALS AND METHODS

Prior to anaesthesia, cardiopulmonary parameters, cloacal temperature, and venous blood gas and biochemistry were obtained from hatchling green sea turtles while they were being gently restrained. Animals were then anaesthetised with ketamine (5 mg kg^-1 ), medetomidine (0.05 mg kg^-1 ) and tramadol (5 mg kg^-1 ) via intramuscular injection. Turtles were checked for the depth of anaesthesia at five-min intervals by recording reflexes (righting, palpebral, pinch, cloacal) and measuring heart rate, respiratory rate and cloacal temperature. After 20 min, a second venous blood sample was obtained for further blood gas and biochemical analysis and the medetomidine was antagonised using atipamezole (5:1 medetomidine, 0.25 mg kg^-1 ).

RESULTS

All turtles were successfully anaesthetised with a mean time to induction of 3.4 min (±1). In all animals, a loss of reflexes (except for palpebral reflex) and voluntary movement was observed for the entire 20 min. Anaesthesia resulted in marked apnoea for the duration of the procedure. Venous blood gas and biochemistry analysis indicated that a 20 min period of apnoea had no measurable effects on venous blood gas results. All turtles recovered uneventfully after atipamazole antagonisation, with a mean time to first breath 4.5 min (±3.7), and mean recovery time 15.5 min (±15.4).

CONCLUSIONS AND CLINICAL RELEVANCE

Intramuscular ketamine-medetomidine-tramadol, antagonised with atipamazole appears to be an effective anaesthetic protocol in hatchling green sea turtles for short procedures with no deleterious effects on venous blood gases or biochemistry.

Heart rate and cardiac response to exercise during voluntary dives in captive sea turtles (Cheloniidae)

In chelonids, oxygen is primarily stored in the lungs during a dive. Therefore, management of blood oxygen transportation to peripheral tissues by cardiovascular adjustments during submergence is crucial to maximize their dive duration, and consequently, the time spent for ecological activities such as foraging. However, the cardiac response to exercise has rarely been examined in sea turtles. In this study, heart rate and its relationship with exercise during voluntary dives were determined in six captive green turtles (19.4±1.5 kg) by simultaneously recording depth, acceleration and electrocardiogram. Our results demonstrated that the heart rate of green turtles was generally low (11.1±0.4 bpm) during resting dives, but they often exhibited instantaneously extreme tachycardia (up to 78.4 bpm). Green turtles elevated their heart rate up to 39.8±1.5 bpm during ventilation after resting dives, while up to 33.1±1.4 bpm after active dives. The heart rate immediately elevated with onset of exercise, and increased linearly with exercise. This result may indicate that turtles immediately need to transport oxygen from the lungs to peripheral tissues by pulmonary and systemic circulations to meet the metabolic demands of exercise because they mainly store oxygen in their lungs.

Hematology and plasma biochemistries in the Blanding's turtle (Emydoidea blandingii) in Lake County, Illinois

Chelonians are one of the most imperiled vertebrate taxa on the planet due to changes in the environment, anthropogenic influences, and disease. Over the last two decades, conservation strategies including nest protection, head-starting and meso-predator control have been successfully adopted by the Lake County Forest Preserve District for a population of state-endangered Blanding's turtles (Emydoidea blandingii) in Illinois. Only recently have efforts expanded to assess the effects of management action on turtle health. The objectives of this study were to 1) establish reference intervals for 16 hematologic and plasma biochemical analytes in free-ranging Blanding's turtles, 2) characterize demographic and temporal drivers of clinical pathology values including age class, sex, month, and year, and 3) describe bloodwork differences between a managed (SBCP) and unmanaged (IBSP) study site. Hematology and plasma biochemistries were performed for 393 turtles from 2017-18 at two sites in the Lake Plain region. Subject or population-based reference intervals were established based on the index of individuality per American Society for Veterinary Clinical Pathology guidelines. Analytes differed by age class [packed cell volume (PCV), total solids (TS), total white blood cell counts (WBC), heterophils, lymphocytes, heterophil:lymphocyte ratio (H:L), total calcium (Ca), calcium:phosphorous (Ca:P), bile acids (BA), aspartate aminotransferase (AST)], sex [H:L, Ca, phosphorus (P), Ca:P, creatine kinase (CK)], month [eosinophils, H:L, Ca, P, uric acid (UA), AST], and year [PCV, WBC, lymphocytes, basophils, H:L, Ca, P, UA]. Several analytes also varied by site [PCV, TS, monocytes, eosinophils, P, UA, AST], suggesting that health status may be affected by habitat management or lack thereof. The results of this study provide a baseline for ongoing health assessments in this region as well as across the Blanding's turtle range.

VENOUS BLOOD GAS AND SELECTED BIOCHEMICAL VALUES FROM AWAKE AND ANESTHETIZED WHITE-BELLIED PANGOLINS ( PHATAGINUS TRICUSPIS)

Pangolins are one of the most-trafficked endangered species and are rare in zoologic collections. Blood gas and select biochemical analysis was performed on nine African white-bellied tree pangolins ( Phataginus tricuspis). Paired blood samples were collected from the ventral tail vasculature prior to (T1) and after 10 min (T2) of sevoflurane anesthesia, and selected blood gas and biochemical parameters were measured using a portable blood gas analyzer. Median (min-max) values for corrected venous blood were pH = 7.372 (7.207-7.529) at T1 and 7.278 (7.124-7.418) at T2. Corrected values were PCO₂ = 51.7 (29.6-69.0) mmHg at T1 and 58.431 (38.1-90.8) mmHg at T2. Clinicians should be aware that this species may hypoventilate while anesthetized with sevoflurane and develop a respiratory acidosis. Concomitant administration of respiratory depressants could compound this effect in a species where oro-tracheal intubation has not been described.

Blood biochemistry and haematology of migrating loggerhead turtles (Caretta caretta) in the Northwest Atlantic: reference intervals and intra-population comparisons

We documented blood biochemistry and haematology of healthy loggerhead turtles (Caretta caretta) in the Northwest (NW) Atlantic in order to establish clinical reference intervals (RIs) for this threatened population. Blood samples were analysed from migratory loggerheads captured off the Mid-Atlantic coast of the USA in 2011, 2012, 2013 and 2016 as part of a long-term research program. Blood variables were determined using a point-of-care analyser, and a veterinary diagnostic laboratory service. We calculated 95% RIs with associated 90% confidence intervals (CIs) for each blood variable. We compared results obtained from our study of migratory loggerheads with published data for similarly sized loggerheads resident at a seasonal temperate latitude foraging area. Significant differences in several blood variables between migratory and resident turtles provided insight on energetic and health status during different behavioural states. Temperature was significantly correlated with several blood variables: lactate, pCO₂, sodium, haemoglobin and lactate dehydrogenase. Our assessment of blood chemistry in healthy loggerhead turtles in the NW Atlantic provides a baseline for clinical comparisons with turtles impacted by anthropogenic and environmental threats, and highlights the importance of identifying unique aspects of biochemical and haematological profiles for sea turtles at the intra-population level.

Venous blood gas in free-living eastern box turtles (Terrapene carolina carolina) and effects of physiologic, demographic and environmental factors

Sustainable wildlife populations depend on healthy individuals, and the approach to determine wellness of individuals is multifaceted. Blood gas analysis serves as a useful adjunctive diagnostic test for health assessment, but it is uncommonly applied to terrestrial reptiles. This study established reference intervals for venous blood gas panels in free-living eastern box turtles (Terrapene carolina carolina, N = 102) from Illinois and Tennessee, and modeled the effects of environmental and physiologic parameters on each blood gas analyte. Blood gas panels included pH, partial pressure of oxygen (pO₂), partial pressure of carbon dioxide (pCO₂), total carbon dioxide (TCO₂), bicarbonate (HCO₃^-), base excess (BE) and lactate. Candidate sets of general linear models were constructed for each blood gas analyte and ranked using an information-theoretic approach (AIC). Season, packed cell volume (PCV) and activity level were the most important predictors for all blood gas analytes (P < 0.05). Elevations in PCV were associated with increases in pCO₂ and lactate, and decreases in pH, pO₂, HCO₃^-, TCO₂ and BE. Turtles with quiet activity levels had lower pH and pO₂ and higher pCO₂ than bright individuals. pH, HCO₃^-, TCO₂ and BE were lowest in the summer, while pCO₂ and lactate were highest. Overall, blood pH was most acidic in quiet turtles with elevated PCVs during summer. Trends in the respiratory and metabolic components of the blood gas panel tended to be synergistic rather than antagonistic, demonstrating that either (1) mixed acid-base disturbances are common or (2) chelonian blood pH can reach extreme values prior to activation of compensatory mechanisms. This study shows that box turtle blood gas analytes depend on several physiologic and environmental parameters and the results serve as a baseline for future evaluation.

Blood biochemistry of olive ridley (Lepidochelys olivacea) sea turtles foraging in northern Sinaloa, Mexico

Blood parameters provide an excellent tool to evaluate the health status of wildlife. However, there are few studies about health parameters of sea turtles in Mexico. For olive ridley turtles (Lepidochelys olivacea), no information was available to establish the health baseline for the species. The objective of this study was to establish reference blood biochemistry values for olive ridley turtles in the northern Sinaloa foraging area. Between 2013 and 2015, 82 olive ridley turtles were captured. Body condition index (BCI) presented a mean of 1.46 ± 0.14 (1.17–2.02) that categorized the population with excellent body condition; in addition, 99% of the turtles captured had a good physical appearance. Blood was collected for biochemistry analysis from 60 turtles. Significantly higher values of total protein, albumin, A/G ratio (albumin/globulin) and PCV (packed cell volume or hematocrit) were observed in adult when compared to subadult turtles. On the other hand, no significant differences were found when females and males were compared. Based on the BCI, physical assessment, and blood parameters, and compared to other sea turtle species, olive ridley turtles in northern Sinaloa were considered in excellent health. To the best of our knowledge, this is the first study to establish normal blood biochemistry values of foraging olive ridley turtles in northern Sinaloa.

Biochemistry and hematology parameters of the San Cristóbal Galápagos tortoise (Chelonoidis chathamensis)

As part of a planned introduction of captive Galapagos tortoises (Chelonoidis chathamensis) to the San Cristóbal highland farms, our veterinary team performed thorough physical examinations and health assessments of 32 tortoises. Blood samples were collected for packed cell volume (PCV), total solids (TS), white blood cell count (WBC) differential, estimated WBC and a biochemistry panel including lactate. In some cases not all of the values were obtainable but most of the tortoises have full complements of results. Despite a small number of minor abnormalities this was a healthy group of mixed age and sex tortoises that had been maintained with appropriate husbandry. This work establishes part of a scientific and technical database to provide qualitative and quantitative information when establishing sustainable development strategies aimed at the conservation of Galapagos tortoises.