THE EFFECTS OF MIGRATORY FLIGHT ON HEMATOLOGIC PARAMETERS IN NORTHERN BALD IBISES ( GERONTICUS EREMITA).

Under the project of "Human-Led Migration," the authors had the unique opportunity to accompany hand-raised northern bald Iibises (NBIs; Geronticus eremita) during migration, which occurred in stages from Bavaria, Germany, to southern Tuscany, Italy. The aim of this study was to investigate the immediate effects of flight, with respect to flight duration, and the more delayed recovery effects on hematologic variables. A total of 31 birds were sampled. Blood samples were taken immediately before takeoff, after landing, and 1 day after the flight. Hematocrit was determined and blood smears were prepared to estimate the total white blood count (tWBC) with leukocyte concentrations (absolute [abs.]) and differential blood cell count (%). Postflight, significant decreases in hematocrit, tWBC, lymphocytes (abs., %), heterophils (abs.), eosinophils (abs., %), and monocytes (abs.) were observed. In contrast, heterophils (%), basophils (%), and the heterophil/lymphocyte (H/L) ratio increased significantly. With increasing flight duration, the H/L ratio increased further. One day postflight, there were still significant decreases in tWBC, lymphocytes (abs.), and eosinophils (abs., %) and significant increases in heterophils (%) and the H/L ratio. The hematocrit dropped even further. These data show that the decrease of tWBC is mainly caused by the lymphocyte fraction and that NBIs need more than 1 day to reverse the postflight changes in some hematologic values. Hematocrit changes postflight and on the recovery day are most likely to be explained by hemodynamics and the metabolic and hormonal changes caused by flight. The hematologic changes postflight in NBIs were largely consistent with those of other birds, but they differed from humans and mammals postexercise mainly in the levels of tWBC, heterophils (matching neutrophils in mammals), and lymphocytes.

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.

Plasma exogenous creatinine excretion for the assessment of renal function in avian medicine--pharmacokinetic modeling in racing pigeons (Columba livia).

The diagnostic evaluation of the glomerular filtration rate by urinary clearance has significant practical limitations in birds because urine is excreted together with feces. Thus, pharmacokinetic modeling of an exogenous plasma creatinine clearance could be useful for assessing renal creatinine excretion in birds. For this study, creatinine (50 mg/kg) was administered to 2 groups of 15 pigeons (Columba livia) each; in one group by the intravenous (IV) route and in the second by the intramuscular (IM) route. The time series of the plasma creatinine concentrations were analyzed by pharmacokinetic models. Body mass-specific creatinine excretion was determined for IV and IM administration to be between 6.30 and 6.44 mL/min per kg, respectively. Body surface area-specific creatinine clearance, which is related to the metabolic rate, was calculated between 0.506 and 0.523 mL/min per dm2, respectively. The results showed that IV as well as IM administration can be used for assessing renal creatinine excretion in pigeons. For practical reasons, IM administration is recommended, with the use of the Bateman function to calculate creatinine elimination.

Computed tomography of coxofemoral injury in five mute swans (Cygnus olor).

Five mute swans (Cygnus olor) were presented with inability to stand or with abnormal positioning of a leg. Clinical examinations indicated the possibility of femoral fractures or coxofemoral luxations. The suspected diagnosis was proven by means of computed tomography (CT), while superimposition of gastrointestinal contents or other artefacts limited radiographic diagnosis in three birds. A typical CT sign for lesions of the coxofemoral joint apart from femoral displacement was haemorrhage within the pelvic bones (especially around the acetabulum), found in four of the five birds. Small femoral head avulsion fractures could be detected only with CT.

Exogenous creatinine clearence indexed to body surface area allows estimation of GFR and across species comparison.

The assessment of renal function in birds is difficult because sensitive biomarkers are lacking. Previous studies have demonstrated the feasibility of measuring the exogenous creatinine clearance in pigeons, indicating the potential use of this technique for the assessment of renal function in birds. The aim of the study was to index the exogenous creatinine elimination rate by body surface area, enabling comparison between different species. Exploratory data on common buzzards (Buteo buteo), Eurasian eagle-owls (Bubo bubo), domestic goose (Anser anser domesticus) and racing pigeons (Columba livia) were collected and indexed by body surface area. A sterile creatinine solution was administered at a dose DM = 50 mg kg-1 i.m. into the deep pectoral muscle of 52 clinically healthy birds of the four species with different body masses. The time course of the plasma creatinine concentration was measured and analyzed by a parametric pharmacokinetic Bateman model, followed by indexing the exogenous creatinine clearance (ECC) by body surface area. The exploratory ECC values for birds with a mean body mass ranging from 0.42 kg (pigeon) to 8.2 kg (goose) were between 0.4261 mL min-1 dm-2 (CI 0.3882-0.4672) and 0.8717 mL min-1 dm-2 (CI 0.8091-0.9362). ECC indexed by body surface area turned out to be independent from body mass. Resulting exploratory data covering species with different body masses are comparable with published data from very complex studies of avian renal function.

Laboratory Evaluation of Renal Function in Birds.

Renal disease often remains undetected in living patients. Urinalysis might contribute to the diagnosis of some kinds of renal and metabolic diseases. Blood uric acid concentrations reflect the excretory functional capacity of the renal proximal tubules. In contrast, blood urea concentrations are significantly affected by the bird's hydration status and have been proposed as a useful variable to detect prerenal causes for renal impairment in birds. Measurement of exogenous creatinine excretion shows promising preliminary results to become a useful test for the assessment of renal excretion in birds.

Pharmacokinetics, tissue concentrations, and safety of the antifungal agent voriconazole in chickens.

Voriconazole, a highly potent triazole antifungal agent with high in vitro activity against a wide variety of fungal pathogens, appears to be an option for the treatment of aspergillosis in birds. To gain initial information on pharmacokinetics, bioavailability, and tissue distribution of voriconazole in birds, we evaluated voriconazole in chickens in a 4-part study that analyzed dose linearity, bioavailability, pharmacokinetics, and tissue distribution. Chickens received voriconazole orally and/or intravenously. Blood samples were drawn and analyzed by validated high-pressure liquid chromatography and high-pressure liquid chromatography coupled with mass spectrometry methods. Voriconazole was detectable at low concentrations in plasma up to 6 hours after oral administration, which resulted in a low absolute bioavailability. Concentrations in tissues 12 hours after administration could be quantified up to 7.37 microg/g (liver). No accumulation in tissues could be detected after 30 days of oral treatment with 10 mg/kg voriconazole. Clinical application of voriconazole for the treatment of aspergillosis in birds appears to be promising, because this drug has a high effectiveness and wide tissue distribution, and long-term treatment did not cause clinical signs of adverse effects or organ damage in chickens.

The cultivable autochthonous microbiota of the critically endangered Northern bald ibis (Geronticus eremita).

The critically endangered Northern bald ibis (Geronticus eremita) is a migratory bird that became extinct in Europe centuries ago. Since 2014, the Northern bald ibis is subject to an intensive rehabilitation and conservation regime aiming to reintroduce the bird in its original distribution range in Central Europe and concurrently to maintain bird health and increase population size. Hitherto, virtually nothing is known about the microbial communities associated with the ibis species; an information pivotal for the veterinary management of these birds. Hence, the present study was conducted to provide a baseline description of the cultivable microbiota residing in the Northern bald ibis. Samples derived from the choana, trachea, crop and cloaca were examined employing a culturomic approach in order to identify microbes at each sampling site and to compare their frequency among age classes, seasonal appearances and rearing types. In total, 94 microbial species including 14 potentially new bacterial taxa were cultivated from the Northern bald ibis with 36, 58 and 59 bacterial species isolated from the choana, crop and cloaca, respectively. The microbiota of the Northern bald ibis was dominated by members of the phylum Firmicutes, followed by Proteobacteria, Actinobacteria, Bacteroidetes and Fusobacteria, altogether phylotypes commonly observed within avian gut environments. Differences in relative abundances of various microbial taxa were evident among sample types indicating mucosa-specific colonisation properties and tissue tropism. Besides, results of the present study indicate that the composition of microbiota was also affected by age, season (environment) and rearing type. While the prevalence of traditional pathogenic microbial species was extremely low, several opportunists including Clostridium perfringens toxotype A were frequently present in samples indicating that the Northern bald ibis may represent an important animal reservoir for these pathogens. In summary, the presented study provides a first inventory of the cultivable microbiota residing in the critically endangered Northern bald ibis and represents a first step in a wider investigation of the ibis microbiome with the ultimate goal to contribute to the management and survival of this critically endangered bird.

Correction: The cultivable autochthonous microbiota of the critically endangered Northern bald ibis (Geronticus eremita).

[This corrects the article DOI: 10.1371/journal.pone.0195255.].

Energy Expenditure and Metabolic Changes of Free-Flying Migrating Northern Bald Ibis.

Many migrating birds undertake extraordinary long flights. How birds are able to perform such endurance flights of over 100-hour durations is still poorly understood. We examined energy expenditure and physiological changes in Northern Bald Ibis Geronticus eremite during natural flights using birds trained to follow an ultra-light aircraft. Because these birds were tame, with foster parents, we were able to bleed them immediately prior to and after each flight. Flight duration was experimentally designed ranging between one and almost four hours continuous flights. Energy expenditure during flight was estimated using doubly-labelled-water while physiological properties were assessed through blood chemistry including plasma metabolites, enzymes, electrolytes, blood gases, and reactive oxygen compounds. Instantaneous energy expenditure decreased with flight duration, and the birds appeared to balance aerobic and anaerobic metabolism, using fat, carbohydrate and protein as fuel. This made flight both economic and tolerable. The observed effects resemble classical exercise adaptations that can limit duration of exercise while reducing energetic output. There were also in-flight benefits that enable power output variation from cruising to manoeuvring. These adaptations share characteristics with physiological processes that have facilitated other athletic feats in nature and might enable the extraordinary long flights of migratory birds as well.

The influence of stress from transport and handling on hematologic and clinical chemistry blood parameters of racing pigeons (Columba livia domestica).

In the present study, the influence of stress from handling and transport on some frequently examined blood parameters of racing pigeons was evaluated. After 3 hr, there was a highly significant (P < 0.01) increase in the number as well as in the percentage of heterophils and decrease of lymphocytes. In clinical chemistries, increases of creatine kinase and glucose and a decrease of uric acid were observed. There was a mean decrease of the total white blood count of >15% that was less significant (P < 0.05). Changes in lactate dehydrogenase, basophils, and monocytes did not prove to be significant; eosinophils, aspartate aminotransferase, total protein, and the packed cell volume were not influenced by stress.

Characterization and quantification of the influence of season and gender on plasma chemistries of Hermann's tortoises (Testudo hermanni, Gmelin 1789).

The present study is the first to monitor plasma chemistries of a group of 30 Hermann's tortoises (HTs) over two summer seasons to characterize and quantify seasonal and gender-related influences. The following analytes were analyzed: ALT, ALP, AST, BA, CA, CHO, CK, LDH, GLU, GLDH, P, TP, TRIG, urea and uric acid. Two-way repeated-measures ANOVA, mean values, confidence intervals were calculated. The overall results showed distinct patterns and somewhat unexpected results concerning the plasma chemistry changes induced by season and gender in a majority of routine biochemical analytes. TRIG, CHO, CA, and P were significantly higher in females. AST, ALT, BA, LDH and GLDH showed an increase in males in midsummer. ALP showed a significant and analogous seasonal variation for both sexes. GLU showed a moderate increase during midsummer. Uric acid and urea concentrations showed a distinct seasonal variation. For some analytes, fitted curves could be calculated describing the seasonal variation.

Comparitive sensitivity of polymerase chain reaction diagnosis of psittacine beak and feather disease on feather samples, cloacal swabs and blood from budgerigars (Melopsittacus undulates, Shaw 18005).

A longitudinal study was performed in order to investigate virus excretion and viraemia during a clinical outbreak of the psittacine beak and feather disease in budgerigars (Melopsittacus undulatus). Viral nucleic acid was detected in feathers, cloacal swabs and blood samples. Overall, beak and feather disease virus (BFDV) DNA was detected most commonly in feather samples, followed by cloacal swabs, and least frequently from blood samples. In most cases the viraemia was short lived and correlated with clinical signs, such as feather abnormalities. Sequence analysis of the polymerase chain reaction fragment amplified from the replication-associated gene (ORF V1) indicated a close relationship with other BFDV isolates. Overall the highest level of nucleotide identity was found with the ORF V1 of another budgerigar isolate. Our results suggest that feather samples and cloacal swabs should be taken for polymerase chain reaction diagnosis to determine the presence of BFDV in an aviary, but that detection in these samples may not correlate well with psittacine beak and feather disease.