AVIAN DISEASES 58:228–231, 2014
Hematologic and Plasma Biochemistry Reference Intervals of Healthy Adult Barn Owls (Tyto alba) Zoltan Szabo,AD Akos Klein,B and Csaba JakabC A
B
Tai Wai Small Animal and Exotic Hospital, 75 Chik Shun Street, Tai Wai, Shatin, New Territories, Hong Kong Department of Animal Ecology and Taxonomy, Faculty of Science, Eo¨tvo¨s Lora´nd University, H-1117, Pa´zma´ny P. se´ta´ny 1/c., Budapest, Hungary C Faculty of Veterinary Science, Szent Istvan University, H-1078, Istvan u. 2., Budapest, Hungary Received 15 November 2013; Accepted 7 January 2014; Published ahead of print 8 January 2014 SUMMARY. Hematologic and plasma biochemistry parameters of barn owls (Tyto alba) were studied in collaboration by the Exotic Division of the Faculty of Veterinary Science of the Szent Istvan University and the Eo¨tvo¨s Lora´nd University, both in Budapest, Hungary. Blood samples were taken from a total of 42 adult barn owls kept in zoos and bird repatriation stations. The following quantitative and qualitative hematologic values were determined: packed cell volume, 46.2 6 4%; hemoglobin concentration, 107 6 15 g/L; red blood cell count, 3.2 6 0.4 3 1012/L; white blood cell count, 13.7 6 2.7 3 109/L; heterophils, 56.5 6 11.5% (7.8 6 2 3109/L); lymphocytes, 40.3 6 10.9% (5.5 6 1.9 3 109/L); monocytes, 1.8 6 2.1% (0.3 6 0.3 3 109/ L); eosinophils, 1 6 1% (0.1 6 0.1 3 109/L); and basophils, 0.6 6 0.5% (0.1 6 0.1 3 109/L). The following plasma biochemistry values also were determined: aspartate aminotransferase, 272 6 43 U/L; L-c-glutamyltransferase, 9.5 6 4.7 U/L; lipase, 31.7 6 11.1 U/L; creatine kinase, 2228 6 578 U/L; lactate dehydrogenase, 1702 6 475 U/L; alkaline phosphatase, 358 6 197 U/L; amylase, 563 6 114 U/L; glutamate dehydrogenase, 7.5 6 2.5 U/L; total protein, 30.6 6 5.3 g/L; uric acid, 428 6 102 mmol/L; and bile acids, 43 6 18 mmol/L. These results provide reliable reference values for the clinical interpretation of hematologic and plasma biochemistry results for the species. RESUMEN. Intervalos de referencia hematolo´gicas y de bioquı´mica plasma´tica de lechuzas comunes adultas sanas (Tyto alba). Se estudiaron los para´metros hematolo´gicos y de bioquı´mica plasma´tica de lechuzas comunes o tambie´n llamadas de campanarios (Tyto alba) con la colaboracio´n de la Divisio´n de Animales Exo´ticos de la Facultad de Ciencias Veterinarias de la Universidad Szent Istvan y de la Universidad Eo¨tvo¨s Lora´nd, ambas localizadas en Budapest, Hungrı´a. Las muestras de sangre fueron tomadas de un total de 42 lechuzas adultas que se encontraban en zoolo´gicos y en estaciones de refugio de aves. Se determinaron los siguientes valores hematolo´gicos cuantitativos y cualitativos: volumen de hematocrito, 46.2 6 4%; concentracio´n de hemoglobina, 107 6 15g/L; recuento de glo´bulos rojos, 3.2 6 0.4 3 1012/L; recuento de glo´bulos blancos, 13.7 6 2.7 3 109/L; hetero´filos, 56.5 6 11.5% (7.8 6 2 3 109/L); linfocitos, 40.3 6 10.9% (5.5 6 1.9 3 109/L); monocitos, 1.8 6 2.1% (0.3 6 0.3 3 109/L); eosino´filos, 1 6 1% (0.1 6 0.1 3 109/L) y baso´filos, 0.6 6 0.5% (0.1 6 0.1 3 109/L). Tambie´n se determinaron los siguientes valores bioquı´micos plasma´ticos: aspartato aminotransferasa, 272 6 43 U/L; L-c-glutamil transferasa, 9.5 6 4.7 U/L; lipasa, 31.7 6 11.1 U/L; quinasa de creatina, 2228 6 578 U/L; lactato deshidrogenasa, 1702 6 475 U/L; fosfatasa alcalina, 358 6 197 U/L; amilasa, 563 6 114 U/L ; glutamato deshidrogenasa, 7.5 6 2.5 U/L; proteı´na total, 30.6 6 5.3 g/L; a´cido u´rico, 428 6 102 mmol/ L y a´cidos biliares, 43 6 18 mmol/L. Estos resultados proporcionan valores de referencia confiables para la interpretacio´n clı´nica de resultados hematolo´gicos y de bioquı´mica plasma´tica para dicha especie. Key words: bird, barn owl, Tyto alba, hematology, biochemistry, blood, reference interval Abbreviations: ALP 5 alkaline phosphatase; AST 5 aspartate aminotransferase; CK 5 creatine kinase; GGT 5 c-glutamyl transpeptidase; GLDH 5 glutamate dehydrogenase; Hb 5 hemoglobin; LDH 5 lactate dehydrogenase; PCV 5 packed cell volume; RBC 5 red blood cell; WBC 5 white blood cell
The barn owl (Tyto alba) is the most widely distributed species of owl; it is found worldwide outside polar and desert regions, and in Asia north of the Alpide belt, most of Indonesia, and the Pacific islands. Because of its wide distribution, the barn owl has formed 36 subspecies. In Hungary, Tyto alba alba and Tyto alba guttata are common (15). The barn owl is a cosmopolitan nocturnal hunter. It is closely associated with people, foraging, nesting, and roosting around human settlements and in agricultural areas. Barn owl populations have been decreasing in number in developed countries in the previous decades, and only 800–1000 pairs live in Hungary (14,15). The main causes of this decline are the loss of traditional nesting sites (e.g., old farm buildings and open spires), the intensification of agriculture, road traffic accidents, and loss of suitable foraging D
Corresponding author. E-mail:
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habitats. Without intensive protection and without work to change public attitudes toward the barn owl, the long-term survival of these marvelous birds is in doubt (14,15). The veterinary care of injured, starving, or poisoned barn owls is a common task of wildlife veterinarians. After proper treatment, some of the injured, sick, poisoned, and debilitated birds can be released back into the wild. During the veterinary treatment of owls, hematologic and plasma biochemistry tests are often required to establish the right diagnosis (3). Knowledge of the reference intervals is necessary for a correct interpretation of the test results. In this study, the reference intervals of hematologic and plasma biochemistry parameters, parameters considered to be very important for the veterinary clinician, were determined. The study was motivated by, to the our knowledge, few such studies in barn owls; we only found two articles about hematology of barn owls. In 1975, Cooper (6) described packed cell volume (PCV), hemoglobin (Hb), and red blood cell (RBC) values of 11 East African barn owls; and in 1998,
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Blood reference intervals of barn owls
Table 1.
Mean, SD, and range of hematologic values for healthy adult barn owls. This study (n 5 31)
Hematology 9
WBC (3 10 /L) RBC (3 1012/L) Hb (g/L) Hemacrit (%) Absolute values Heterophils (3 109/L) Lymphocytes (3 109/L) Monocytes (3 109/L) Eosinophils (3 109/L) Basophils (3 109/L) Differential Heterophils (%) Lymphocytes (%) Monocytes (%) Eosinophils (%) Basophils (%)
Mean 6 SD
Range
13.7 3.2 107 46.2
6 6 6 6
2.7 0.4 15 4
8.4–19.0 2.3–4.1 75–126 40–53
7.8 5.5 0.3 0.1 0.1
6 6 6 6 6
2.0 1.9 0.3 0.1 0.1
2.5–11.1 2.5–9.9 0.0–1.4 0.0–0.5 0.0–0.3
56.5 40.3 1.8 1 0.6
6 6 6 6 6
11.5 10.9 2.1 1 0.5
20.0–76.0 23.0–79.0 0.0–9.0 0.0–3.0 0.0–2.0
Hawkey and Samour (9) described several hematology parameters of 10 barn owls. We did not find any normal values for plasma biochemistry parameters of barn owls. As regard other owl species Spagnolo et al. (23) described the hematologic, biochemical, and protein electrophoretic values of 10 captive tawny owls (Strix aluco) in 2008, and Chan et al. (5) described hematology and plasma biochemistry parameters of 38 adult captive collared scops owls (Otus lettia) in 2012. MATERIALS AND METHODS This study was conducted between 2002 and 2006, during which time blood samples were taken from 42 adult (.1-yr-old) healthy barn owls held in captivity. The owls belonged to the bird population of some Hungarian zoos (Budapest Zoo and Botanical Garden; ‘Ka´lma´n Kittenberger’ Zoo and Botanical Garden, Veszpre´m; Game Preserve of Kecskeme´t; Zoo and Botanical Garden of Ja´szbere´ny) and bird repatriation stations (Barn Owl Foundation, Gyo¨mro˝; Bird Hospital in Hortoba´gy; ‘Istva´n Chernel’ Bird Protection Centre and Memorial Museum, Ko˝szeg; Misina Nature and Animal Protecting Association, Pe´cs). Because all the adult owls included in this study had been captured in the wild previously, their precise age could not be determined. Neither could their sex be ascertained using physical examination because barn owls do not have sexual dimorphism. Coelioscopy and DNA analysis were not performed for sex identification. The birds were manually restrained with a help of a thick towel. Before sampling, all of the birds were physically examined by an expert veterinarian who was experienced in examining wild and zoo animals. Most of the birds had suffered previously road traffic accidents or other traumas, and some of them had wing and leg fractures. However, these injuries were already healed at the time of the blood sampling, and the examining veterinarian declared each owl clinically normal. The health status of the owls was determined by their clinical history and by physical examination. No additional diagnostic procedures were performed. Any animal with signs of disease, unhealed injuries, anorexia, or weight loss was excluded from the study. Withdrawal and storage of blood samples. Blood samples were taken from the wing vein (v. cutanea ulnaris) of conscious barn owls before the morning feeding, using a 22 gauge needle. For hematologic examinations, a 0.3-ml blood sample was taken into tubes containing K3EDTA, whereas for the determination of biochemistry parameters, 1 ml of blood was withdrawn into tubes containing lithium-heparin. After sampling, blood smears were made from blood that had not yet
Hawkey and Samour (9) (n 5 10) Mean 6 SD
16.6 2.7 142 46
6 6 6 6
4.2 0.3 15 3
Cooper (6) (n 5 11)
Range
Mean
11.5–22.3 2.2–3.0 127–164 42–51
8.9 6 3 5 6 1.7
2.16 187 43.7
Range
1.7–2.75 115–231 36–52
5.2–12.5 2.5–7.5 0–1 0–2.5 0–0.9
been exposed to anticoagulant. Once dried, the smears were fixed in methanol. Blood samples treated with anticoagulant were transported at a temperature between 1 C and 4 C to the Clinical Laboratory of the Department of Internal Medicine of the Faculty of Veterinary Science, Szent Istvan University, Budapest, Hungary. In the laboratory, the heparinized blood samples were centrifuged, and a hematologic analysis was carried out within 12 hr of withdrawal. The samples were stored at 2–4 C pending plasma biochemistry analyses that were carried out within 24 hr after blood sampling. Hematologic analyses. PCV was determined by the microhematocrit method (Z-233M-2 centrifuge, Hermle Labortechnik GmbH, Wehingen, Germany), whereas Hb concentration was measured using a Minidil-2 automatic hematologic analyzer (Diatron Ltd., Budapest, Hungary). RBC and white blood cell (WBC) counts were determined using a Buerker chamber by the method of Natt and Herrick (20). Blood smears were stained with May-Gru¨nwald Giemsa stains (ReanalKer Ltd., Budapest, Hungary), and the differential blood count was taken by counting 200 cells in each smear (3). Only smears with ,25% smudge cells were used for hematologic analysis. Plasma biochemistry analyses. Plasma was obtained by centrifugation. Plasma biochemistry parameters were determined with an RX Daytona automatic analyzer (Randox Laboratories Ltd., Crumlin, Antrim, U.K.). Total plasma protein (7), aspartate aminotransferase (AST, glutamic-oxaloacetic transaminase) (1), alkaline phosphatase (13), L-c-glutamyltransferase (24), lactate dehydrogenase (LDH) (11), creatine kinase (CK with N-acetylcysteine) (2), amylase (19), lipase (16), and uric acid (25) were assayed with commercial reagent kits (Diagnosticum Co., Budapest, Hungary). Bile acids (17,18,21) and glutamate dehydrogenase (GLDH) (22) were determined with Randox procedures (Randox Laboratories Ltd.)
RESULTS
No hemoparasites or hemopathologic changes were detected in any of the individual blood smears. The hematologic and plasma biochemistry values (mean, SD, ranges) of healthy, captive, adult barn owls (n 5 42) are presented in Tables 1 and 2. DISCUSSION
Hematologic and plasma biochemistry parameters may be influenced markedly by the habitat (4), health status (8), age (12),
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Z. Szabo et al.
Table 2. Mean, SD, and range of plasma biochemistry values for captive, healthy adult barn owls. This study, barn owls (n 5 42) Mean 6 SD
AST (U/L) GGT (U/L) Lipase (U/L) CK (U/L) LDH (U/L) ALP (U/L) Amylase (U/L) GLDH (U/L) Total protein (g/L) Uric acid (mmol/L) Bile acids (mmol/L)
272 9.5 31.7 2228 1702 358 563 7.5 30.6 428 43
6 6 6 6 6 6 6 6 6 6 6
43 4.7 11.1 578 475 197 114 2.5 5.3 102 18
Spagnolo et al. (23), tawny owls (n 5 4–8)
Range
175–335 1.2–19 10–59 1190–3585 1028–2374 115–658 302–823 4.3–12.4 24–42 280–646 20–89
and husbandry and nutrition (10) of the birds. The hematology values measured in adult barn owls in this study were compared with those obtained by Cooper (6) and Hawkey and Samour (9) (Table 1). The hematocrit values were similar in all three studies (present study, 46.2%; Hawkey and Samour, 46%; and Cooper, 43.7%). The total WBC, heterophil, lymphocyte, monocyte, eosinophil, and basophil counts of our study and those of Hawkey and Samour (9) were also similar. Heterophils were found to be the most common cell type (56.5%), followed by lymphocytes (40.3%), whereas the proportions of the other WBC types were relatively small. The RBC count of our study was close to Hawkey and Samour (9) result but higher than the result Cooper described (6) (this study, 3.2 3 1012/L; Hawkey and Samour, 2.7 3 1012/L; and Cooper, 2.16 3 1012/L). In the present study, much lower Hb value was measured than the high value reported by Cooper (6). Our Hb value was closer to, but lower than the value determined by Hawkey and Samour (9) (this study, 107 g/L; Hawkey and Samour, 142 g/L; and Cooper, 187 g/L). Because we did found any publications about the normal plasma biochemistry parameters of barn owls, the values of our study were compared with the Spagnolo et al. (23) results of tawny owls and the Chan et al. (5) results of collared scops owls (5) (Table 2). The uric acid values were similar in all three studies (this study, 428 mmol/L; Spagnolo et al., 457 mmol/L; Chan et al., 523 mmol/L). The AST results of Spagnolo et al. (23) and our study were similar but approximately five times higher than the values Chan et al. (5) reported (this study, 272 U/L; Spagnolo et al., 281 U/L; and Chan et al., 59 U/ L). Our study’s c-glutamyl transpeptidase (GGT) (9.5 U/L) and total protein (30.6 U/L) values were lower than those that Spagnolo et al. (23) described. The CK (2228 U/L) and LDH (1702 U/L) enzymes in our study were much higher than the values Chan et al. (5) reported. The alkaline phosphatase (ALP) value of our study was between the values that Spagnolo et al. (23) and Chan et al. (5) reported (this study, 358 U/L; Spagnolo et al., 629 U/L; and Chan et al., 179 U/L). The difference between the biochemistry parameters can be caused by the different methods used in the mentioned studies. In Chan et al. (5), the biochemical plasma analyses were undertaken using an automated clinical dry chemistry analyzer (Dri-Chem 3000, Fujifilm, Tokyo, Japan). However, in Spagnolo et al. (23), the plasma was immediately frozen at 230 C, and samples were analyzed within 2 mo by using an automated analyzer and liquid reagents (Eos Bravo, Hospitex Diagnostics, Firenze, Italy). For lipase, GLDH, and bile acids, no reference values were found in the literature to which the present results could be compared. A limitation of our study is that only captive barn owls were examined. Husbandry and nutrition that differed from the natural
Mean
Chan et al. (5), collared scops owls (n 5 33–37)
Range
Mean
Range
281 31
214–368 4–77
59
37–82
86
2–344
629
184–1459
346 678 179 601
50–849 285–1170 89–375 200–1024
38.6 457
33.5–54 282–632
47 523
34–58 273–945
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