Haematological reference values for East African wild ungulates

Researchin VeterinaryScience1993,54, 261-263

Haematological reference values for East African wild ungulates J. M. SLEEMAN, University of Tennessee, College of Veterinary Medicine, Department of Environmental Practice, PO Box 1071, Knoxville, TN37901-1071, USA, M.-A. WIDDOWSON*, 151 Sheen Road, Richmond upon Thames, Surrey, TW9 1 YS

Basic haematological values were obtained in the field from shot, clinically normal, wild East African ungulates. The species studied were: Thomson's gazelle (Gazella thomsoniO,Grant's gazelle (Gazellagrantil),blue wildebeest (Conochaetes taurinus), Coke's hartebeest (Alcelaphus buselaphus cokiO, impala (Aepyceros melampus) and Burchell's zebra (Equusburchelh). Red cell parameters compared well with previous reports although the mean cell haemoglobin concentrations were higher. The white cell counts were considerably lower in all species. The red and white cells of all species studied had standard mammalian morphology. Generally, the field equipment used worked well under the conditions encountered, although the field microscope made cell counting troublesome and the heat made the preservation of fixed slides difficult. VERY little is known about basic haematological parameters of African wild mammals. Most of the information on the haematology of exotic species has been derived from captive animals which may be influenced by effects of the animals' environment in captivity (Flesness 1986, Fowler 1986, Bennett et al 1991). Basic haematological values are useful in the differential diagnosis of diseases in captive wild animals and help to identify errors of management, as shown by Bush and Smith (1980). It is often difficult to detect when wild animals are ill and therefore haematology is valuable in determining subclinical diseases. Haematological values for wild animals are also necessary to monitor the indigenous population of animals; this is of increasing importance for endangered populations where veterinary intervention may be required. The aims of this communication are to present haematological values from clinically normal wild ungulates and to discuss field haematological techniques. The data were collected between August 2 and September 5, 1990, at an altitude of 1600 m at Game Ranching, Athi River, Kenya. The blood samples were taken from wild animals culled at night by a single shot to the head. Animals selected for shooting were judged to be of adult size *Present address:Blackmanand O'Gorman,GroveCottage,Oxford Road, Newbury,Berkshire 261

and no discrimination by sex was made. All the animals were clinically examined immediately after death. No abnormalities were detected. All the animals used in the study were passed fit for human consumption. There was little or no chase of the animals before they were shot and death was usually instantaneous. Venous blood samples were then taken from the severed jugular veins within one to two minutes of death. The blood was collected in commercially available plastic tubes containing ethylene diamine tetra-acetic acid (EDTA). Analysis of the samples was performed two to 24 hours after sampling. The animals were divided into adults and juveniles on the basis of dentition. Red and white blood cell counts were made using a Hawkesley improved Neubauer counting chamber, and a field microscope (Swift FM-31; Swift Instruments) by the techniques described by Archer (1977). Packed cell volume (pcv) was measured by means of a Compur Minihaematocrit Centrifuge, Model M l l 0 1 (Bayer Diagnostics uK) and haemoglobin concentration was measured by the cyanmethaemoglobin method using a Compur Mini-photometer Model M1100 (Bayer Diagnostics UK). Two blood films from each individual were prepared, one of which was fixed and stained by the Giemsa method (Archer 1977). Unstained films were examined in the field for red cell morphology and blood-borne parasites. Differential white cell counts on the stained films were then obtained on return to the United Kingdom using a standard laboratory microscope. The blood samples were also centrifuged using a manual centrifuge for 10 minutes. Total protein measurements were made on the plasma obtained using a hand held refractometer (Atago). The results are presented in Table 1. There was little variation between the species in haemoglobin, PCV, mean cell haemoglobin concentration (MCHC), but more in number (red blood cell count), and size (mean cell volume [MCV]) of red cells as might have been expected (Hawkey 1991). The red blood cells of the impala were extremely small and numerous, perhaps an indication of better adaptation to altitude, or a reflection of a mountain-dwelling ancestry. A high red cell count has been demonstrated to be associated with a small cell size (Hawkey 1975), and has also

262

J. M. Sleeman, M.-A. Widdowson

TABLE 1: Reference haematologieal values for six East African ungulates Zebra

Thomson's gazelle

Grant's gazelle

(Equus burchelh)

( Gazella thomsonil)

( Gazella grantit)

Number of animals

(9)

(11)

Female: male Average weight (kg) Hb (g d1-1)

4:5 258.0 16.71 +2.20 (12.60 - 19-00) 40.40 -+ 7.20 (26.00 - 49.00)

Pcv (%)

RBC (X1012 litre-1) MCV (fl)

MCH (pg) MCHC (g dl-1)

WSC (xl09 litre-1) Neutrophils (%)

Lymphocytes (%)

Monocytes (%)

Eosinophils (%)

Coke's hartebeest

Impala

Wildebeest

(Alcelaphus buselaphus cokll)

(Aepyceros melampus)

( Conochaetes taurinus)

(8)

(10)

(7)

(7)

7:4 19.9 17.13+2.58 (12.00 - 22.00) 41-00 _+5.83 (32-00 - 51.00)

2:6 53.7 18.78+0.29 (18.30 - 19.00) 45.88 _+2.71 (39.00 - 48.00)

5:5 105-0 16.25-+2.12 ( 1 3 . 2 0 - 19.20) 39.20 _+7.68 (28.00 - 50.00)

2:5 51.3 16-93+1.49 (14-30 - 19.50) 44-00 + 6.16 (38.00 - 54-00)

9.45_+1.48 (8.22 - 12.55) 43.44 _+8.77 (28.90 - 56.00)

9.24+1.77 (7-00 - 11.20) 47.03 + 8.05 (39.60 - 62.90)

8.75+1.19 (6.88 - 11.10) 53-21 + 8.26 (41.00 - 68-00)

13.41 (8.20 31.59 (16.50

_+4-01 - 23.55) + 11.53 - 36.80)

23.27_+5.31 (15.45 - 31.85) 19.27 + 5.74 (10.60 - 26.00)

17.92 (14.00 42.04 (30-40

19.10+3.87 (12.20 - 25.90) 42.04 _+2.03 (37.50 - 44.50)

21.78_+3.07 (17.10 - 27.90) 41.03 _+2.41 (38.50 - 49.90)

13-09 _+3.93 ( 6 . 1 0 - 21-80) 40.10 _+2-78 (36.90 - 43.60)

7.64 _+ 1-87 ( 5 . 4 0 - 10.60) 38.81 + 3.65 (36.00 - 47.00)

1.31 + 0.93 (0.35 - 3.75) 14-50 -+ 14.75 (1-00 - 52.00) (n = 8) 70.13 _+22-98 (46.00 - 93-00) (n = 8) 1.25 _+ 1.71 (0.00 - 4.00) (n = 8) 0.25 + 6-00 (0.00 - 6.00) 0.50 + 1.00 (0.00 - 3.o0) (n = 8) 5.50 + 5-57 (0.00 - 18.00) 5.98 + 0-58 (4.90 - 6-90) (n=8)

1.63 _+0.87 (0.60 - 3.55) 13.75 -+ 20.98 (0.00 - 80.00) (n = 4) 67.75 _+20.77 (46.00 - 89.00) (n = 4) 0-50 + 0.50 (0-00 - 1.00) (n = 4) 0 (n = 4)

1.93 (0.70 49.10 (34.00

3.41 + 1.52 (1-00 - 5.10) 8-00 -+ 6.00 (1.00 - 14-00) (n = 4) 74.00 _+23.02 (36.00 - 98.00) (n = 4)

1:6 196.0 16.90+2.16 ( 1 3 . 0 0 - 19.70) 43.80 + 4.91 ( 3 4 . 0 0 - 50.00) (n = 6) 12.60 + 2,07 (9.60 - 15.80) 35.13_+6-13 (27.00 - 45.60) (n = 6) 13.61 + 2.37 (10.5 - 17.9) 40.05 -+ 2.62 37-00 - 44-00) (n = 6) 2.36 -+ 0.64 (1.65 - 3.60) 46.00 -+ 13.40 (29.00 - 74.00)

+ 2-72 -- 23.70 _+5.25 - 48.50

4.37 + 1.72 (2-10-7.15) 53.11 + 17.43 (26.00 - 73.00) 49.17 _+ 18.69 (18.00 - 65.00) 2.00 + 1.89 (0-00 - 7.00) 3.61 _+2.21 8.00)

(1.00 Basophils (%)

(0.00 - 1.00) Degenerate cells (%) Total protein (g dl-~)

2.89 (0.00 7-80 (6.40

_+3.40 - 11.00) + 0.73 - 8.60)

0

-+ 1.07 - 4.35) + 14.45 - 84.00)

41.40 -+ 14.90 (13.00 - 66.00)

0.86 + 0.99 (0.00 - 3.0O)

(0.00 - 1.00)

(0.00- t . 0 0 )

1.90 + 1.78 (0-00 - 6.00) 0

0.75 + 0.83 (0.00 - 2-00) 0

3.14+2-10 ( 0 . 0 0 - 6-00) 0-71 + 0.7O (0.00 - 2.OO)

5.50 (0.00 6.64 (5.00

10.25 + 8-32 (1.00 - 22.00) 6.23 + 0.77 (5.00 - 7.40) (n=6)

4.00 + (0-00 6-14 + (5.00 -

(n = 4) 4.00 _+2.50 (0.00 - 7.00) 5.74 _+0.60 (4.50 - 6.20) (n=4)

45.23 + 10.70 (23.00 - 61.00)

+ 4.50 - 14.00) _+ 1.09 - 9.50)

2.50 7.00) 0.81 7.60)

Results are presented as means with the standard deviations. The ranges of values are given in brackets. Hb Haemoglobin concentration, PCV packed cell volume, RBC Red blood cell number, MCV Mean cell volume, MCH Mean cell haemoglobin, MCHC Mean cell haemoglobin concentration, WBC White blood cell number

been observed in impala by Young (1966) and Drevemo et al (1974). The red cell parameters and total protein results presented in this study are, in general, comparable with other studies (Young 1966, Drevemo et al 1974, Seal and Schobert 1976, Seal et al 1977, Pospisil et al 1989) and with the LYNX d a t a b a n k of the Zoological Society of London (Bennett et al, 1991) which contains haematological parameters from animals in the collections of the Zoological Society of London at Regent's Park and Whipsnade Zoos. The MCHC values in this study, however, are consistently higher than previously reported, and this is almost certainly due to a lack of standardisation of the Compur Mini-photometer because of the uncertain validity of standards in field conditions. The white cell, monocyte, eosinophil and basophil counts were considerably lower than published values

in all species. The low eosinophil counts are interesting as they may indicate a lack of significant parasitism, although microfilaria of unknown species were present on the blood smears from one zebra. The lymphocyte counts, however, are higher than published values. The red and white cells in all species studied had standard mammalian morphology. Sickle-shaped red cells have been demonstrated in deer (Hawkey 1975) but were not seen in any of the animals. The red cells of the zebra had a tendency to form rouleaux as seen with blood from domestic horses. There were no obvious differences in the results associated with either age, sex, pregnancy or lactation, though the sample size was not large enough to establish any trends such as have been reported by Hawkey (1975, 1991). Generally, the techniques worked well under field conditions. The Compur system was particularly useful,

Haematological valuesfor wild ungulates being lightweight, battery powered and portable, and produced consistent results. Dollin (1981) also demonstrated a close agreement of haemoglobin and pcv estimations obtained using the Compur system compared with methods in standard use. The Compur system is, therefore, to be recommended for this type of field work. The Mini-photometer, however, is not suitable for determining red cell counts unless precalibrated for the species (Dollin 1981). The manual centrifuge was also found to be a reliable method of producing plasma in the field, with the advantages of being relatively lightweight and functioning without a power source. A number of difficulties were encountered during the field work. Although the field microscope was lightweight, it was difficult to use due to its small size. This problem was compounded by the relatively small size of some species' red blood cells. A further problem stemmed from the inverted light source, which meant that the counting chamber was also inverted and thus cells and the ruled area were not in the same focal plane. On examination of the fixed, stained smears, many white cells were found to be degenerate, most probably due to heat, lack of refrigeration facilities and poor fixing techniques. Some of the very low neutrophil and relatively high lymphocyte counts may be explained by the difficulties in the differential counting of poorly prepared and preserved smears. Several factors must be considered in the examination of the results. First, it is known that shooting may cause stress and consequent splenic contraction, which may cause an increase in the red cell counts and associated parameters (Drevemo et al 1974). The effect on the results of this study is unknown, although the shooting was relatively quick and clean. Drevemo et al (1974), however, found a significant difference between drug-immobilised and shot animals. This difference may be explained by the fact that drug-immobilisation can cause a significant decrease in red cell counts, Pcv and haemoglobin concentration (Seal et al 1972, Presidente et al 1973, Drevemo and Karstad 1974). Drevemo and Karstad (1974) also found a decrease in the white cell counts in drug-immobilised animals. Other local factors which have been shown to have an effect are altitude, nutrition, subclinical disease and, as shown by Pospisil et al (1989), season of the year. Extension of the study could include blood samples from the ranch cattle population for comparison with baseline African bovine data. This would help identify any variables due to local condi'tions.

263

D e p a r t m e n t of Clinical Veterinary Medicine, University of Cambridge, and Dr M. Sommerlatte and Mr P. Tilley at Game Ranching Ltd. Thanks also to Mrs Margaret Harding, James Hampson, Jo Beresford and Simon Tucker. This project was sponsored by Veterinary Times/Willows Francis; the Jowett Fund, Cambridge Veterinary School; Intervet and Churchill and Clare Colleges, University of Cambridge.

References ARCHER, R. K. (1977) Technical methods. In Comparative Clinical Haematology. Eds R. K. Archer and L. B. Jeffcott. Oxford, Blackwell Scientific Publications BENNETT, P. M., GASCOYNE, S. C., HART, M. G., KIRKWOOD, J. K. & HAWKEY, C. M. (1991) Development of LYNX: A computer application for disease diagnosis and health monitoring in wild mammals, birds and reptiles. Veterinary Record 128, 494499 BUSH, M. & SMITH, E. E. (1980) Clinical chemistry and hematology as diagnostic aids in zoological medicine. In Comparative Pathology of Zoo Animals. Eds R. J. Montali and G. Migaki. Washington, Smithsonian Institution Press DOLLIN, B. E. (1981) Haematology estimation by means of the Compur system compared with methods in standard use. Journal of Small Animal Practice 22, 623-628 DREVEMO, S., GROOTENHUIS, J. G. & KARSTAD, L. (1974) Blood parameters in wild ruminants in Kenya. Journal of Wildlife Diseases 10, 327-334 DREVEMO, S. & KARSTAD, L. (1974) The effect of xylazine and xylazine-etorphine-acepromazine combination on some clinical and haematological parameters in impala and eland. Journal of Wildlife Diseases 10, 377-383 FLESNESS, N. (1986) Normal Physiological Values. Apple Valley, Minnesota, International Species Inventory System (ISIS) FOWLER, M. E. (1986) Zoo and Wild Animal Medicine. Philadelphia, W. B. Saunders HAWKEY, C. M. (1975) Comparative Mammalian Haematology. London, William Heinemann. pp 3-15, 159-165 HAWKEY, C. M. (1991) The value of comparative haematological studies. Comparative Haematology International 1, 1-9 POSPISIL, J., KASE, F. & VAHALA, J. (1989) Comparison of basic haematological values in Grevy's zebras (Equus grevy 0 during the summer and winter seasons. Comparative Biochemistry and Physiology 92A, 31-32 PRESIDENTE, P. J. A., LUMSDEN, J. H., PRESNELL, K. R., RAPLEY, W. A. & McCRAW, B. M. (1973) Combination of etorphine and xylazine in captive white-tailed-deer: II. Effects on hematologic, serum biochemical and blood gas values. Journal of Wildlife Diseases 9, 342-348 SEAL, U. S., OZOGA, J. J., ERICKSON, A. W. & VERME, L. J. (1972) Effects of immobilization on blood analyses of white-taileddeer. Journal of Wildlife Management 36, 1034-1040 SEAL, U. S. & SCHOBERT, E. E. (1976) Baseline data for the Grant's gazelle (Gazella grantiO. Journal of Zoo Animal Medicine 7, 7-10 SEAL, U. S., SCHOBERT, E. E. & GRAY, C. W. (1977) Baseline laboratory data for the Grant's zebra (Equus burchelli boehmi) Journal of Zoo Animal Medicine 8, 7-15 YOUNG, E. (1966) A preliminary report on blood findings in twenty species of wild mammals. Journal of the South African Veterinary Medical Association 37, 95-97

Acknowledgements Many thanks to Dr C. Hawkey, Mr M. Hart, Dr J. Kirkwood at London Zoo, Dr S. Lloyd at the

Received August ]8, 1992 Accepted November 11, 1992