Laboratory blood analysis in Strigiformes-Part I: hematologic reference intervals and agreement between manual blood cell counting techniques

Automated hematological cell count using sysmex XN-1000V in Testudo hermanni: Agreement with manual count

Mediterranean area represents the main habitat of Testudo hermanni. Clinical signs of disease of these tortoises are non-specific, making the hematology results crucial in revealing underlying pathological conditions. However, accurate automated identification of blood cell populations is hampered by the presence of nucleated erythrocytes (NRBC) and thrombocytes (Thr), necessitating manual methods such as counting chambers. The aim of the study was to assess the performance of the novel automated hematology analyzer Sysmex XN-1000 V, which includes a a specific channel (WNR) for counting NRBC, in accurately identify and quantify the different blood cell populations of Testudo hermanni. Additionally, its agreement with manual counts was evaluated. Fifty heparinized blood samples were initially counted using the Neubauer improved chamber and then analysed twice with Sysmex XN-1000 V. Thirteen out of 50 samples were instrumentally counted again after 48 h to assess the inter-assay precision. All WNR scattergrams were re-analysed using an ad hoc gate panel to differentiate two populations: NRBCs (weak fluorescence signal) and WBC + Thr (high fluorescence signal). Sysmex XN-1000 V demonstrated optimal intra- and inter-assay precision for NRBCs (CV 0.98% ± 1.96; 1.31% ± 2.98) and moderate precision for WBC + Thr (CV 9.24% ± 16.61; 12.69% ± 10.35). No proportional nor constant errors were observed between the methods for both the populations. The instrumental NRBC counts were consistently slightly lower, while WBC + Thr counts were slightly higher compared to manual counts. These findings suggest that Sysmex XN-1000 V can be used for analyzing cell populations in heparinized blood of Testudo hermanni. However, specific instrumental reference intervals are suggested.

COMPARISON OF HEMATOLOGIC DIFFERENCES WITH LITHIUM HEPARIN AND DIPOTASSIUM ETHYLENEDIAMINETETRAACETIC ACID IN EUROPEAN STARLINGS (STURNUS VULGARIS)

Preservation of blood through use of anticoagulants allows delayed assessment of hematologic health and is commonly employed in veterinary health assessments. The two most common anticoagulants are lithium heparin (LH) and dipotassium ethylenediaminetetraacetic acid (EDTA), and their effects can vary widely between species. The hematologic effects of these anticoagulants on blood from European starlings (Sturnus vulgaris) have not been established, and these birds could serve as models for passerine species both in managed collections and in the wild. Blood was drawn from 45 European starlings and immediately divided into either LH or EDTA microtainers. For each sample, packed cell volume (PCV), total solids (TS), and complete blood counts were performed. There were no significant differences between EDTA and LH anticoagulated blood for PCV, white blood cell count (WBC) slide estimates, WBC determined by Leukopet, absolute heterophils, absolute lymphocytes, absolute monocytes, absolute eosinophils, or absolute basophils. Blood anticoagulated with EDTA had higher total solids than blood mixed with LH. For both anticoagulants, Leukopet-measured total WBC were consistently higher than blood film estimates. There were no subjective morphologic differences for WBC and no hemolysis observed in the samples. Thrombocyte clumping was prominent for LH blood samples and minimal for EDTA samples. These results reveal that LH and EDTA are both suitable anticoagulants for use in European starlings, and EDTA may be superior for diagnostic purposes or for qualitative evaluation of thrombocyte quantity.

Determination of Coagulation Parameters by Whole Blood Dynamic Viscoelastic Coagulometry in Strigiformes

No reference values are available in Strigiformes to evaluate blood coagulation using dynamic viscoelastic coagulometry (DVC) with the Sonoclot (Sienco, Boulder, CO, USA) analyzer. The objectives of this study were 1) to assess the feasibility of DVC in Strigiformes, 2) to calculate the index of individuality of each coagulation parameter, and 3) to assess interspecies variability and establish reference intervals, if relevant, based on the index of individuality. Fresh whole blood samples were obtained from healthy Strigiformes, including 13 barred owls (Strix varia), 10 great horned owls (Bubo virginianus), 6 snowy owls (Bubo scandiacus), and 7 eastern screech owls (Megascops asio), and analyzed with DVC with glass bead (gb) and kaolin clay (k) coagulation activators. Activated clotting time (ACT), clot rate (CR), and platelet function were determined immediately after collection using fresh native whole blood. Intraindividual variability was assessed with a second fresh native whole blood sample from 5 barred owls. Interindividual variability was assessed using a Kruskall-Wallis test. For the parameters gbACT (n = 35), gbCR (n = 34), and kACT (n = 27), no significant differences were detected between species (all P ≥ 0.05). Based on low index of individuality, global Strigiformes reference intervals were determined for gbACT (32.3-852.5 seconds; n = 35), gbCR (0-20.1 units/min; n = 29), and kACT (0-1570.3 seconds; n = 27). In conclusion, DVC can be used in Strigiformes and the gb coagulation activator would be more appropriate when basal individual values are not available in a tested individual.

Assessment of avian health status: suitability and constraints of the Zoetis VetScan VS2 blood analyser for ecological and evolutionary studies

Biochemical analyses of blood can decipher physiological conditions of living animals and unravel mechanistic underpinnings of life-history strategies and trade-offs. Yet, researchers in ecology and evolution often face constraints in which methods to apply, not least due to blood volume restrictions or field settings. Here, we test the suitability of a portable biochemical analyser (Zoetis VetScan VS2) for ecological and evolutionary studies that may help solve those problems. Using as little as 80 µl of whole-bird blood from free-living Jackdaws (Corvus monedula) and captive Zebra Finches (Taeniopygia guttata), we show that eight (out of 10) blood analytes show high repeatability after short-term storage (approximately 2 h) and six after 12 h storage time. Handling stress had a clear impact on all except two analytes by 16 min after catching. Finally, six analytes showed consistency within individuals over a period of 30 days, and three even showed individual consistency over a year. Taken together, we conclude that the VetScan VS2 captures biologically relevant variation in blood analytes using just 80 µl of whole blood and, thus, provides valuable physiological measurements of (small) birds sampled in semi-field and field conditions.

Hematology, Ultrastructure and Morphology of Blood Cells in Rufous-Winged Buzzards (Butastur liventer) from Thailand

In attempt to treat injured raptors and promote conservation awareness, the Kasetsart University Raptor Rehabilitation Unit (KURRU) was established in 2007. The complete blood counts (CBCs) are a manual tool used for the screening of raptor health. These tests require knowledge of blood cell morphology. This study aimed to describe the preliminary information of the hematology, ultrastructure, and morphology of blood cells in rufous-winged buzzards (RWB). There were 17 RWBs admitted into the KURRU. CBCs were manually performed by veterinary technicians. The morphology and morphometry of blood cells were observed from Wright-stained blood smears. Ultrastructure was observed from uranyl acetate and lead citrate-stained sections. The hematologic values were analyzed and described from individual RWBs that were clinically healthy, negative for blood parasites, and had PCV > 0.30 L/L. Consequently, CBCs of 12 out of 17 RWBs were included for descriptive hematologic values. Heterophils were the most prevalent white blood cells in RWBs. Of these 17 RWBs, 1 non-parasitized RWB showed hypochromic erythrocytes with PCV 0.18 L/L, which indicated that anemia in RWBs resulted from non-parasitic causes. The morphology of blood cells in RWBs was similar to those in other diurnal raptors, except that the lymphocytes showed pale or colorless cytoplasm. The electron micrographs highlighted that the basophil contained two types of granules: homogeneous electron-dense granules and reticulated electron-dense granules. The photomicrographs in this report are the scientific reference for identification of blood cells in RWBs. The CBCs from non-parasitized RWBs (clinically healthy) can be used as a cage mate reference in the KURRU. Additionally, we found evidence that evaluations of blood smears together with CBC examination were important in raptors.

REFERENCE VALUES AND COMPARISON OF BLOOD CHEMISTRY AND PLASMA PROTEIN VALUES BETWEEN GOLD STANDARD ANALYZERS AND FOUR POINT-OF-CARE DEVICES IN FREE-RANGING CANVASBACKS (AYTHYA VALISINERIA)

Accurate, timely, and cost-effective blood chemistry analysis is an essential tool for directing emergency treatment, monitoring the health status of captive and free-ranging individuals and flocks, and improving the efficacy of conservation actions. Blood samples were obtained from 52 canvasbacks (Aythya valisineria) that were captured on San Francisco Bay, California, during December 2017 as part of a long-term study. Reference values and clinical agreement were determined for blood chemistry and plasma protein parameters among four commonly used point-of-care devices (VetScan^® VS2, i-STAT^®, AlphaTRAK^®2 glucometer, refractometer) and two gold standard laboratory analyzers (Roche cobas^® c501, Helena SPIFE 3000 system). Canvasback reference values were generally within expected ranges for Anatidae species with the exception of higher upper limits for sodium and chloride. Creatine kinase and aspartate transaminase values exceeded a published threshold for diagnosis of capture myopathy even though study birds were captured using low-stress techniques and successfully released. With the exception of higher alkaline phosphatase in hatch-year canvasbacks, no age or sex differences were observed for any analyte in this population that was captured during a nonbreeding period. Analysis of analyzer agreement found raw VetScan aspartate transaminase, calcium, glucose, and uric acid values; corrected VetScan albumin, potassium, sodium, and total protein values; raw i-STAT glucose and potassium values; and corrected i-STAT sodium and chloride values were clinically interchangeable with Roche cobas values. Raw VetScan and i-STAT glucose values were also interchangeable. However, none of the Roche or point-of-care analyzer plasma protein values were in clinical agreement with gold standard electrophoresis values. The findings of this study highlight the need for analyzer- or technique-specific reference values and provide biologists and veterinarians quantitative reference values using currently available analyzers to better assess and respond to the health of individuals and populations.

Molecular and Morphological Analyses of Leucocytozoon Parasites (Haemosporida: Leucocytozoidae) in Raptors From Thailand

INTRODUCTION

Leucocytozoon spp. causes a vector-borne disease that is nonpathogenic in domestic and wild birds. To date, there was no report of leucocytozoonosis in raptors from Thailand.

METHODS

This study was carried out to perform morphological and molecular analyses of Leucocytozoon in 400 raptors at a rehabilitation center at Kasetsart University, Thailand during a 7-year period. The nested PCR was used to amplify the cytochrome b gene of Leucocytozoon with primers HaemNF1 and HaemNR3 as the primary reaction.

RESULTS

The light microscopic examination revealed Leucocytozoon gametocytes in five raptors; three diurnal raptors [two Crested Goshawks (CGs, Accipiter trivirgatus) and one Eastern Imperial Eagle (EIE, Aquila heliaca)], and two nocturnal raptors (one Oriental Scops-Owl (OSO, Otus sunia,) and one Short-eared Owl, Asio flammeus) and two species were identified: Leucocytozoon danilewskyi in both owl species and L. californicus in two CGs. The PCR method revealed more infection rate (2.0%, 8/400) than the light microscopic method including one Barred Eagle-Owl (BEO, Bubo sumatranus), one Brown Hawk Owl (BHO, Ninox scutulata) and one OSO. A phylogeny revealed that sequences from one SEO and one OSO were clustered with L. danilewskyi and the three Leucocytozoon sequences from diurnal raptors were clustered with L. californicus. The other three sequences from a BHO, a BEO and an OSO were ambiguous.

CONCLUSION

This study combined morphological, morphometric and molecular phylogenetic analyses to identify L. danilewskyi in two species of owls, L. californicus in three diurnal raptors, and unknown species in three other owls, representing the first records of leucocytozoon infection in raptors from Thailand.

Effects of Season, Location, Species, and Sex on Hematologic and Plasma Biochemical Values and Body Mass in Free-ranging Grebes (Aechmophorus species)

The effects of season, location, species, and sex on body weight and a comprehensive array of blood chemistry and hematology analytes were compared for free-ranging western (Aechmophorus occidentalis) and Clark's (Aechmophorus clarkii) grebes. Birds (n = 56) were collected from Puget Sound, WA, and Monterey Bay and San Francisco Bay, CA, from February 2007 to March 2011. The data supported generalization of observed ranges for most analytes across Aechmophorus grebe metapopulations wintering on the Pacific coast. Notable seasonal and location effects were observed for packed cell volume (winter 6% greater than fall; winter California [CA] 5% greater than Washington [WA]), total white blood cell count (CA 3.57 × 10³ cells/µL greater than WA), heterophils (WA 10% greater than CA), lymphocytes (winter 19% greater than fall), heterophil to lymphocyte ratio (fall 5.7 greater than winter), basophils (CA greater than WA), plasma protein (WA about 10 g/L [1.0 g/dL] greater than CA), plasma protein to fibrinogen ratio (winter about 15 greater than fall), potassium (CA 2 mmol/L greater than WA), and liver enzymes (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase: WA greater than CA). Within California, season had a greater effect on body mass than sex (mean winter weights about 200 g greater than fall), whereas within a season, males weighed only about 80 g more than females, on average. These data give biologists and veterinarians quantitative reference values to better assess health at the individual and metapopulation level.

Complete Blood Cell Count and White Blood Cell Counting Method Comparison in 49-day-old Bobwhite Quail (Colinus virginianus)

The northern bobwhite quail (Colinus virginianus) is a game bird experiencing decline throughout much of its range. There are limited species-specific and age-specific hematologic data for bobwhite quail. Complete blood cell counts in eighteen 49-day-old captive-raised quail of unverified sex were used to contribute data to reference intervals for the species as juvenile animals. Values for packed cell volumes, total solids, red and white blood cell counts, and white cell differential calculations were recorded for each animal. Bobwhite quail of this age were found to be primarily lymphocytic, but considerable variability was observed. White blood cell counts were obtained by estimates from blood smears and Phloxine B stain. White blood cell counts performed with ×1000 magnification did not compare well with other white blood cell methods, including Phloxine B stain.

A fatal case of a captive snowy owl (Bubo scandiacus) with Haemoproteus infection in Japan

Parasites of the genus Haemoproteus are vector-borne avian haemosporidia commonly found in bird species of the world. Haemoproteus infections are typically considered relatively benign in birds. However, some Haemoproteus species cause severe disease and mortality, especially for captive birds removed from their original habitat. In September 2018, a captive 15-year-old snowy owl (Bubo scandiacus), kept in a zoological garden of Japan, died subacutely after presenting leg dysfunction. This case showed significantly low PCV and elevated AST, ALT, CK, and LDH values. Many megalomeronts with prominent morphological characteristics of Haemoproteus were observed in the left leg muscles. Those megalomeronts exhibited multilocular structures and were internally filled with merozoites. A new lineage of Haemoproteus was detected by subsequent PCR for the cytochrome b (cytb) gene of avian haemosporidia from DNA extracted from several organ tissues. The detected lineage was classified in the subgenus Parahaemoproteus and was similar to those from the wild birds inhabiting the region including the study area, suggesting that this snowy owl likely acquired its infection from wild birds. This is the first report of a fatal case of a captive bird with a locally transmitted Haemoproteus infection in Japan. We considered the pathogenicity of this infection in conjunction with the clinical course and hematology results. We surmise that snowy owls may be particularly susceptible to infection with Haemoproteus parasites, and warming northern temperatures may exacerbate the overall health of these and other high latitude birds. Further research into the prevalence of Haemoproteus in wild birds near zoological gardens and potential biting midge vectors is necessary for the ex situ conservation of introduced birds.

Effects of Isoflurane Anesthesia on the Hematologic Values of Rehabilitated Wild Owls

Isoflurane anesthesia is commonly used for owls when they are being rehabilitated to minimize stress during treatments and procedures, as well as to ensure caretaker safety. However, the effects of isoflurane anesthesia on the hematologic response of owls are not known. To investigate the effects of isoflurane anesthesia on the hematology of owls, 3 phases of investigation were performed on the subject animals: 1) single, short manual- versus single, short isoflurane-restraint episodes (n = 12; 38%); 2) a single, prolonged isoflurane episode (n = 10; 31%); and 3) serial, short isoflurane episodes (n = 10; 31%). All owls were classified as adult, and the sex for most individuals was unknown. Twelve owls (38%) were included in phase 1: 5 great horned owls (Bubo virginianus; 42%), 2 eastern screech owls (Megascops asio; 17%), and 5 barred owls (Strix varia; 42%). A separate cohort of 10 novel owls (31%) were selected for inclusion in both phases 2 and 3: 4 great horned owls (40%), 2 eastern screech owls (20%), 2 barred owls (20%), 1 barn owl (Tyto alba; 10%), and 1 snowy owl (Bubo scandiacus; 10%). For each anesthetic episode, blood was collected within 3 minutes of capture and in 15-minute intervals according to the duration of the procedure. Phase 2 had additional blood collections with the patient awake at 2 and 24 hours after time 0 blood collection, whereas phase 3 had an additional blood collection at 24 hours after time 0 blood collection. Hematologic analyses included packed cell volume, total solids, total white blood cell count, heterophil to lymphocyte ratio, and absolute heterophil, lymphocyte, monocyte, eosinophil, and basophil counts. Total white blood cell count decreased significantly during phase 1; packed cell volume decreased significantly during phases 2 and 3; total solids decreased significantly in phase 2; phase 2 demonstrated a lymphopenia with a concurrent decrease in the heterophil to lymphocyte ratio; and phase 3 demonstrated a heteropenia and significant changes in the eosinophil count. All hematologic changes noted in the study were within appropriate reference intervals for the owls but do suggest that there are physiologic consequences of restraining and anesthetizing these avian patients.

Advances in Exotic Animal Clinical Pathology

Over the last 10 years, exotic animal clinical pathology has been evolving, improving health assessment in avian, mammal, fish, reptile, and amphibian patients. These advances are reviewed in this article. Species-specific reference intervals for blood parameters are becoming more available (eg, for ionized calcium, endocrine panels, and vitamin D plasmatic concentrations). In addition, new technologies are being developed to facilitate targeted metabolite detection and result acquisition by veterinarians. Novel techniques, biomarkers, and clinical changes related to disease have been described in avian, mammal, fish, reptile and amphibian species. The use of mobile applications may also be helpful.

Successful Management of Open, Contaminated Metacarpal Fractures in an Adult Snowy Owl ( Bubo scandiacus) With a Minimal Type II External Skeletal Fixator

An adult, male snowy owl ( Bubo scandiacus) was found down and unable to fly in western New York State. Physical examination and radiographs revealed a subacute, open wound and fractured major and minor metacarpals of the right wing. A minimal type II external skeletal fixator (ESF) device was placed on the right major metacarpal bone and the open wound was allowed to granulate and close. After evidence of bone union, the ESF device was removed. The owl performed auto-physiotherapy throughout the process and was released with sustained flight 2 months postoperatively. It was recaptured 7 weeks later and underwent further rehabilitation to allow successful release 11 months after surgical stabilization. To our knowledge, this is the first case report describing use of a type II ESF device on the metacarpus of a bird.

Haemoproteus in barn and collared scops owls from Thailand

The barn owl (BO) and the collared scops owl (CSO) are common nocturnal raptors throughout Thailand. Blood samples from 23 adult BOs and 14 CSOs were collected and processed for complete blood cell counts and parasite morphological examinations. Two Haemoproteus-positive samples were processed for ultrastructural observation. Polymerase chain reaction (PCR) analysis for a partial cytochrome b gene (cytb) from Haemoproteus was performed in all samples. Haemoproteus presence detected by light microscopy was lower than that detected by PCR (30.4% and 34.8%, respectively, in BO; and 50.0% and 78.6%, respectively, in CSO). Comparative hematology revealed that Haemoproteus-positive BOs had higher mean cell hemoglobin concentration, total leukocyte, absolute heterophil, basophil, and monocyte counts than Haemoproteus-negative BOs, but no significant differences between Haemoproteus-negative and -positive CSOs. Monocyte ultrastructure analysis revealed a role in the elimination of gametocytes. Morphologically, the Haemoproteus in 3 BOs and 6 CSOs were identified as H. noctuae, while that in 1 CSO was identified as H. syrnii. Phylogenetic analysis indicated the Haemoproteus spp. in 8 BOs and 7 CSOs were not closely related to H. noctuae or H. syrnii, and the cytb of 2 CSOs was that of H. syrnii. These results should be useful for study of Haemoproteus.

Hematologic reference intervals and age effect in European Strigiformes

BACKGROUND

The clinical importance of hematologic testing in avian veterinary medicine is reflected in the increasing number of studies for the establishment of hematologic RIs of Strigiformes and other species. Age is an important physiologic factor in birds and the effect on hematology variable should be understood.

OBJECTIVES

The objective of this study was to determine baseline data of hematologic variables in 5 species of Iberian Strigiformes in different age classes.

METHODS

Nocturnal birds of prey were sampled at Wildlife Health Centers. Packed cell volume was determined by the microhematocrit centrifugation method, and RBC and WBC counts were determined using the direct hemocytometer count method with Natt and Herrick solution. Hemoglobin concentration was measured spectrophotometrically. The MCV, MCHC, and MHC were calculated using the standard formulas. The differential WBC count was performed by the routine microscopic evaluation of 200 cells on a blood smear manually stained with Wright stain. Thrombocyte blood count estimate was obtained from the blood film.

RESULTS

No differences were observed between juveniles and adults for any variable evaluated in Tawny owl, Little owl, Scops owl, Long-eared owl, and Barn owl. In addition, PCV, RBC, and HGB of chicks were statistically significantly lower than in juveniles and adults, and total WBC was significantly higher in Tawny owl, Little owl, Scops owl, and Long-eared owl.

CONCLUSIONS

Our findings provide evidence that laboratory data from chicks of Strigiformes are different compared to juveniles and adults; therefore, separate RIs were defined.

EXPLORATORY PLASMA BIOCHEMISTRY REFERENCE INTERVALS FOR URAL OWLS (STRIX URALENSIS, PALLAS 1771) FROM THE AUSTRIAN REINTRODUCTION PROJECT

The Ural owl (Strix uralensis) is the biggest forest-living owl in Austria; however, it became extinct in Austria through poaching and habitat loss more than half a century ago. The birds examined in the present study were breeding pairs from the reintroduction project with the aim of determining exploratory plasma biochemistry reference intervals in Ural owls and evaluating the amount of biological variation between seasons, sexes, and ages. A total of 45 birds were sampled, including 13 adult males, 14 adult females, and 18 juvenile birds. Remarkably, almost all of the analytes showed significant differences between the subgroups, primarily between seasons, followed by age and sex. Only creatinkinase, glucose, lactatdehydrogenase, and triglycerides did not show any significant variations. Despite partitioning of reference values into subgroups according to biological variation diminishing the number of reference individuals in the respective groups, the resulting smaller reference intervals will improve medical assessment. The results of the present study once again demonstrate that significant seasonal fluctuations must be expected and considered in the interpretation. It can be assumed that these differences are probably even greater in free-range birds with considerable changes in food quantity and quality during and between years.

OPHTHALMIC REFERENCE VALUES AND LESIONS IN TWO CAPTIVE POPULATIONS OF NORTHERN OWLS: GREAT GREY OWLS (STRIX NEBULOSA) AND SNOWY OWLS (BUBO SCANDIACUS)

This study established ophthalmic reference values and characterized ocular lesions in two captive populations of boreal owls, including 46 eyes of 23 great grey owls (Strix nebulosa) and 38 eyes from 19 snowy owls (Bubo scandiacus). A complete ophthalmologic exam was conducted, including neuro-ophthalmic reflexes, Schirmer tear test I (STT-I), intraocular pressure (IOP) using rebound tonometry, fluorescein staining, horizontal corneal measurements using Jameson calipers, direct and indirect ophthalmoscopy, and ocular ultrasound biometry. Eyes with an STT of <5 mm/min, outliers, and eyes with severe diseases were excluded from reference value analysis. No statistically significant differences were found between right or left eyes in either species or among individuals in different age groups and sexes. Mean intraocular pressures and Schirmer tear tests were also not statistically significantly different between great grey owls and snowy owls (IOP: 9.6 ± 2.6 mm Hg and 9.1 ± 1.9 mm Hg, respectively, and STT-I: 9.8 ± 2.8 mm/min and 9.8 ± 2.4 mm/min, respectively). However, snowy owls overall had a significantly larger eye than did great grey owls, reflected in corneal diameters (23.4 ± 1 vs. 20.0 ± 0.8 mm, respectively) and sonographic biometry. In both species, the most common ocular lesions included keratitis, cataracts, chorioretinal lesions, and abnormal pecten. Establishment of reference ocular parameters will help wildlife veterinarians and rehabilitators determine an appropriate treatment plan and will aid in correctly identifying the presence of ocular disease.