Validation of lactate measurement in American flamingo (Phoenicopterus ruber) plasma and correlation with duration and difficulty of capture

Measuring the Level of Agreement for Lactate Measurements in Hispaniolan Amazon Parrots (Amazona ventralis) Among 2 Point-of-Care Analyzers and a Benchtop Analyzer

Lactate is an important biochemistry analyte used in human and veterinary medicine to assess tissue perfusion and can be used as a prognostic indicator for certain disease conditions. Whereas lactate is commonly measured using "patient-side" handheld meters, these meters have not been validated for companion avian species. The purpose of this study was to measure the level of agreement between 2 commercially available point-of-care lactate meters and a laboratory benchtop blood analyzer in Hispaniolan Amazon parrots (Amazona ventralis). Blood samples were collected from 20 adult parrots at Louisiana State University by drawing 1.5 mL of blood from the right jugular vein. One drop of whole blood was used for the Lactate Plus analyzer and the remainder of the sample transferred into a lithium heparin microtainer. From the blood in the microtainer, 0.2 mL whole blood was analyzed using the epoc Blood Analysis System, and the remaining sample was centrifuged to obtain plasma that was immediately frozen at -80°C (-112°F) and submitted to the Texas A&M University Clinical Pathology Laboratory for analysis on the VITROS 4500 benchtop analyzer. Bland-Altman agreement plots and Passing-Bablok regression were used to measure the level of agreement between the methods. There was poor agreement between all 3 methods with mean percentage differences in lactate concentrations ≥22% (epoc and Lactate Plus: 33.6% [95% CI: 27-40]; epoc and VITROS 4500: 55% [95% CI:52-58]; VITROS 4500 and Lactate Plus: 22% [95% CI:16-28]). Based on these results, the point-of-care meters tested in this study are not interchangeable, and separate reference intervals were calculated for each method. Blood lactate concentrations may have more utility in tracing lactate trends over time in an individual rather than being able to utilize this information at 1 time point for disease diagnosis and prognosis.

INVESTIGATING BLOOD LACTATE CONCENTRATION AS A PROGNOSTIC INDICATOR FOR BIRDS PRESENTING WITH BREVETOXICOSIS: 2020-2021

Large blooms of the dinoflagellate Karenia brevis cause annual harmful algal bloom events, or "red tides" on Florida's Gulf Coast. Each year, the Clinic for the Rehabilitation of Wildlife (CROW) is presented with hundreds of cases of aquatic birds that exhibit neurologic clinical signs due to brevetoxicosis. Double-crested cormorants (Phalacrocorax auratus) are the most common species seen, and typically present with a combination of ataxia, head tremors, knuckling, and/or lagophthalmos. Blood lactate levels are known to increase in mammals for a variety of reasons, including stress, hypoxia, sepsis, and trauma, but there is limited literature on blood lactate values in avian species. The objective of this study was to determine the prognostic value of blood lactate concentration on successful rehabilitation and release of birds presenting with clinical signs consistent with brevetoxicosis. Blood lactate levels were collected on intake, the morning after presentation and initial therapy, and prior to disposition (release or euthanasia) from 194 birds (including 98 cormorants) representing 17 species during the 2020-2021 red tide season. Overall, mean blood lactate at intake, the morning after intake, and predisposition was 2.9, 2.8, and 3.2 mmol/L, respectively, for released birds across all species (2.9, 2.9, and 3.2 mmol/L for released cormorants); 3.4, 3.4, and 6.5 mmol/L for birds that died (4.0, 3.5, and 7.9 mmol/L for cormorants that died); and 3.1, 3.5, and 4.7 mmol/L for birds that were euthanized (3.5, 4.7, and 4.9 mmol/L for cormorants that were euthanized). On average, birds that died or were euthanized had an elevated lactate at all time points as compared to those that were released, but these results were not statistically significant (P = 0.13). These results indicate that blood lactate levels do not appear to be useful as a prognostic indicator for successful release of birds, including double-crested cormorants, affected by brevetoxicosis.

Use of Blood Lactate in Assessment of Manual Capture Techniques of Zoo-Housed Crocodilians

Simple Summary

This study aimed to clarify the relationship between manual capture techniques, blood lactate levels, and other varying factors in order to minimize physiological stress during manual capture and restraint events of zoo-housed crocodilians. While following the St. Augustine Alligator Farm Zoological Park’s capture and restraint protocol, 53 blood samples from ten crocodilian species were collected and analyzed for lactate. These measurements were then related to specific behavioral and extrinsic factors. We sought to define blood lactate as a new welfare marker for crocodilians in zoos. Based on our findings, we are able to recommend some best practices for manual capture methods for crocodilians.

Abstract

Species-specific welfare indicators are important in promoting positive welfare for zoo animals. Reptiles are a notoriously understudied group in regards to behavior, welfare needs, and husbandry requirements. Using opportunistically obtained samples, we evaluated how blood lactate is affected by variation in manual capture and restraint in crocodilians. Lactate is an indicator of anerobic metabolism in reptiles. It offers a relatively simple and indirect way to assess physiological stress. Determining the best way to reduce struggling during capture and associated stress is of great importance to these species’ overall welfare. Blood samples (N = 53) were collected from 10 different species of crocodilians. It was found that age class was a significant predictor variable of lactate levels after capture, and longer handling time seemed to cause an increase in lactate. Finally, draining enclosure pools for a small number of the captures was associated with higher lactate levels compared to other capture factors that were recorded. This study showed that welfare of captive crocodilians could be improved by shortening the duration of physical restraint events when possible. Developing objective measures of welfare and establishing baseline recommendations for care and handling of crocodilians will ultimately promote and improve their wellbeing, along with that of other understudied reptiles in zoos.

LACTIC ACIDOSIS INDUCED BY MANUAL RESTRAINT FOR HEALTH EVALUATION AND COMPARISON OF TWO POINT-OF-CARE ANALYZERS IN HEALTHY LOGGERHEAD SEA TURTLES (CARETTA CARETTA)

Sea turtles are often restrained manually for brief periods during veterinary evaluation and care in rescue, rehabilitation, research, and aquarium settings. Blood gas values and lactate are routinely evaluated during triage of sea turtles, and lactate clearance is of prognostic significance in cold-stunned individuals. Although increases in blood lactate have been associated with muscle exertion, experimental forced submergence, trawl and pound net capture, and general anesthesia, changes in blood lactate associated with short periods of manual restraint have not been evaluated. Venous blood gas and lactate values were tested in 16 juvenile loggerhead sea turtles (Caretta caretta) before and after manual restraint for a 15-min routine veterinary examination. The agreement of blood lactate values between two point-of care analyzers (i-STAT and Lactate Plus) was also compared. Blood pH and bicarbonate (HCO₃^-) decreased significantly (P < 0.001), and partial pressure of carbon dioxide (pCO₂) increased significantly (P < 0.0001) after 15 min. Lactate increased significantly between time points for both analyzers (P < 0.0001). Linear regression analysis showed excellent correlation for lactate measurements obtained on both analyzers (r = 0.998). The mean difference in lactate concentrations between the analyzers was statistically significant, indicating that the methods cannot be used interchangeably (P < 0.0001). Deming regression and Bland-Altman plots identified a slight negative proportional bias for lactate measurement by the Lactate Plus compared with the i-STAT. These results suggest that clinicians should evaluate blood gas values and lactate at the beginning of health evaluations and interpret serial lactate values in sea turtles with caution, because even short periods of manual restraint can induce lactic acidosis and considerably influence these values.

Outside the Box: Working With Wildlife in Biocontainment

Research with captive wildlife in Animal Biosafety Level 2 (ABSL2) and 3 (ABSL3) facilities is becoming increasingly necessary as emerging and re-emerging diseases involving wildlife have increasing impacts on human, animal, and environmental health. Utilizing wildlife species in a research facility often requires outside the box thinking with specialized knowledge, practices, facilities, and equipment. The USGS National Wildlife Health Center (NWHC) houses an ABSL3 facility dedicated to understanding wildlife diseases and developing tools to mitigate their impacts on animal and human health. This review presents considerations for utilizing captive wildlife for infectious disease studies, including, husbandry, animal welfare, veterinary care, and biosafety. Examples are drawn from primary literature review and collective 40-year experience of the NWHC. Working with wildlife in ABSL2 and ABSL3 facilities differs from laboratory animals in that typical laboratory housing systems, husbandry practices, and biosafety practices are not designed for work with wildlife. This requires thoughtful adaptation of standard equipment and practices, invention of customized solutions and development of appropriate enrichment plans using the natural history of the species and the microbiological characteristics of introduced and native pathogens. Ultimately, this task requires critical risk assessment, understanding of the physical and psychological needs of diverse species, creativity, innovation, and flexibility. Finally, continual reassessment and improvement are imperative in this constantly changing specialty area of infectious disease and environmental hazard research.

Evaluation of the anesthetic and cardiorespiratory effects of intramuscular alfaxalone administration and isoflurane in budgerigars (Melopsittacus undulatus) and comparison with manual restraint

OBJECTIVE To evaluate the anesthetic and cardiorespiratory effects of IM alfaxalone and isoflurane administration in budgerigars (Melopsittacus undulatus) and compare use of these agents with use of manual restraint. ANIMALS 42 healthy budgerigars. PROCEDURES For dose comparison, birds received alfaxalone (5 or 10 mg/kg [2.27 or 4.54 mg/lb], IM; groups A5 and A10, respectively; n = 6/group). For treatment comparison, birds received alfaxalone (10 mg/kg, IM) or isoflurane (via face mask) or were manually restrained (groups A, I, and M, respectively; n = 10/group). Data were obtained on onset, degree, and duration of sedation or anesthesia; heart and respiratory rates; and recovery times. Birds in the treatment comparison underwent physical examination and blood gas analysis. RESULTS All group A5 birds became sedate, but not recumbent. In group A10, 5 of 6 birds lost the righting reflex; however, none lost the noxious stimulus response. Median time to initial effects was significantly shorter and mean time to complete recovery was significantly longer in group A10 than in group A5. Heart and respiratory rates in group A10 remained clinically acceptable; however, some birds had signs of excitement during induction and recovery. Times to initial effects, recumbency, and complete recovery were significantly longer, yet clinically practical, in group A than in group I. Plasma lactate concentrations were significantly higher in group M than in groups A and I. CONCLUSIONS AND CLINICAL RELEVANCE Alfaxalone administered IM at 10 mg/kg produced effective sedation in healthy budgerigars and may be a viable alternative to isoflurane and manual restraint for brief, minimally invasive procedures. Brief manual restraint resulted in a significant increase in plasma lactate concentration.

Erosive Enteritis and Intestinal Obstructions Caused by Decomposed Granite in a Flock of Lesser Flamingos (Phoeniconaias minor)

Decomposed granite is a material commonly used in zoos as a base for flamingo exhibits. In 2012, the artificial turf over the decomposed granite in the Fort Worth Zoo flamingo exhibit was removed and pressure washed, the granite was replaced, and the turf was then restretched in place. Approximately 8 months later, 3 lesser flamingos (Phoeniconaias minor) showed signs of lethargy and hematochezia. Results of physical examination revealed poor body condition in all birds, with variable hematologic abnormalities, including anemia, hypoproteinemia, and electrolyte disturbances. Radiographs of birds showed large amounts of radiopaque material in the ventriculus and dilated intestinal loops. Two birds died either during treatment or surgery, and 1 bird was euthanatized. Postmortem examination of all 3 birds revealed large amounts of fine, granite-like material in the ventriculus and intestines, severe congestion of intestinal mucosa, and obstruction of intestinal lumen by caseous plugs surrounded by fecal material. Microscopic evaluation of the material removed from the ventriculus showed birefringent crystals that corresponded to microscopic silica grains, consistent with the decomposed granite from the exhibit. Histologic examination of tissues showed marked chronic erosive colitis, mild erosive proventriculitis, and lesions in the muscular layer of the ventriculus. Subsequently, 82 remaining flamingos in the flock were radiographed. Results showed the same material in the ventriculus of most birds, but no intestinal obstructions were identified. Different treatment techniques were attempted unsuccessfully to remove the material from the flamingos that had the largest amount of decomposed granite in their gastrointestinal tracts. Ultimately, all birds were treated with oral gastrointestinal protectants, adsorbents, laxatives, and lubricants, along with antibiotics administered in drinking water. No further mortalities occurred once medical treatments were implemented.

Comparison of the Sedative Effects of Alfaxalone and Butorphanol-Midazolam Administered Intramuscularly in Budgerigars (Melopsittacus undulatus)

Intramuscular (IM) administration of either alfaxalone or butorphanol with midazolam was evaluated for sedation and effects on heart and respiratory rates in budgerigars (Melopsittacus undulatus). Twenty adult budgerigars were randomly assigned to receive 1 of 2 treatments: alfaxalone at 15 mg/kg IM or butorphanol and midazolam at 2.5 mg/kg IM and 1.25 mg/kg IM, respectively. Baseline heart and respiratory rates and sedation score were collected and, after injection, time to initial effects and initial recumbency were recorded. Five minutes after injection, birds were assessed for a righting reflex, and, if absent, response to noxious stimulus was assessed by hemostat clamp on the first digit. Birds then underwent a standardized diagnostic evaluation of radiographs, jugular venipuncture, and physical examination. At the end of the physical examination, a sedation score was assigned, and birds were placed in dorsal recumbency for recovery. Times from injection to initial arousal, final recumbency, standing, and full recovery were recorded. Although time to onset of sedation was the same between groups, alfaxalone produced a shorter (P = .04) and more consistent duration of sedation (mean ± SD: 27.5 ± 5.9 minutes) compared with butorphanol-midazolam (72.0 ± 56.9 minutes). Only 3 of 10 birds receiving butorphanol-midazolam were recumbent by 5 minutes compared with 10 of 10 birds receiving alfaxalone. Radiographs were successfully obtained in 9 of 10 and 7 of 10 birds administered alfaxalone and butorphanol-midazolam, respectively. No adverse effects were observed in any bird. Intramuscular alfaxalone produces safe, effective, and reliable sedation in budgerigars and is a more consistent and shorter duration alternative to intramuscular butorphanol-midazolam.

Haematology and biochemistry of the San Cristóbal Lava Lizard (Microlophus bivittatus)

The San Cristóbal lava lizard, Microlophus bivittatus, is one of nine species of lava lizards endemic to the Galápagos Islands of Ecuador. No information presently exists about baseline health parameters for any of these species. We analysed blood samples drawn from 47 lizards (25 males and 22 females) captured at two locations on San Cristóbal Island. A portable blood analyser (iSTAT) was used to obtain near-immediate field results for total CO₂, lactate, sodium, potassium, ionized calcium, glucose and haemoglobin. Standard laboratory haematology techniques were employed for differential white blood cell counts and haematocrit determination. Body temperature, heart rate and body measurements were also recorded. We found significant differences in haematocrit values between males and females. The values reported in this study provide baseline data that may be useful in detecting changes in health status among lava lizards affected by natural disturbances or anthropogenic threats. Our findings might also be helpful in future efforts to demonstrate associations between specific biochemical or haematological parameters and disease. Because there are several related species on different islands in the Galápagos archipelago, comparisons between populations and species will be of interest. Lay Summary:Haematology and biochemistry values of the San Cristóbal lava lizard Microlophus bivittatus, along with several other health parameters (morphometrics and temperature), are reported for the first time.

Assessment of a portable lactate meter for field use in the white rhinoceros (<i>Ceratotherium simum</i>)

Blood lactate is a predictor of mortality in critically ill humans and animals. Handheld lactate meters have the potential to be used in the field to evaluate the condition of severely injured rhinoceroses but have not been compared with laboratory-based methods. Agreement between a handheld lactate meter and a laboratory method was assessed, as was the stability of rhino blood lactate in the anticoagulant sodium fluoride/potassium oxalate (fluoride/oxalate). Blood samples were obtained from 53 white rhinos that had been immobilised for management reasons. Lactate was measured by means of a handheld meter using whole blood in heparin (WBHEP), whole blood in fluoride/oxalate (WBFO) and fluoride/oxalate plasma (PFO). Results were recorded in both blood (BL) and plasma (PL) modes and compared to an established laboratory method for measuring plasma lactate. To assess the stability of lactate over time, blood lactate in fluoride/oxalate was measured on the handheld meter at intervals for up to 91 h. Agreement was best using WBFO in PL mode, with small bias (−0.16), tight 95% limits of agreement (LOA) (−1.46, 1.14) and a Pc (95% CI) of 0.97 (0.92, 0.99). The agreement was improved for all sample types when using the PL mode compared to the blood lactate (BL) mode. Blood lactate was stable in fluoride/oxalate for 91 h, with a mean change from baseline of 0.15 (−0.178, 0.478) mmol/L (mean, 95% CI). The handheld meter was found to be suitable for field use in white rhinos but provided more reliable results with the device in PL mode. Furthermore, rhino blood lactate was found to be stable in fluoride/oxalate for as long as 3 days.

Multimodal Drug Therapy and Physical Rehabilitation in the Successful Treatment of Capture Myopathy in a Lesser Flamingo (Phoeniconaias minor)

A wild-caught lesser flamingo (Phoeniconaias minor) from the Fort Worth Zoo (Fort Worth, TX, USA) presented with moderate lameness that progressed to the inability to stand 2 days after restraint and handling. Results of blood tests showed severely elevated creatine phosphokinase (CPK) and aspartate aminotransferase (AST) activities, confirming suspected capture myopathy. Intensive supportive therapy, consisting of intravenous fluids and muscle relaxants, along with physical rehabilitation therapy, nutritional support, and anxiolytics, were instituted to aid in relaxation and muscle regeneration. After 2 weeks of intensive therapy, the bird showed substantial improvement and could remain standing throughout the day after being assisted to a standing position. By day 23, the bird was able to stand independently and walk completely unassisted, with no discernible lameness. The bird has subsequently remained healthy since it was returned to the flock approximately 27 days after it was first presented for treatment. Although anecdotal communications of successful treatment of this condition in flamingos exist, this is the first report, to our knowledge, that describes in detail the successful treatment of capture myopathy in any flamingo species. Success in this case is attributed to the combination of early fluid and drug therapy, intensive physical rehabilitation therapy, and anxiolytics to counteract the hyperexcitable nature of this wild-caught bird.

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.