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DETAILED HAEMATOLOGY / BIOCHEMISTRY - Editorial Comment

Editorial Comment (Editorial Overview Text Replicated on Overall Species page - Ursus maritimus - Polar bear)

HAEMATOLOGY:

BIOCHEMISTRY:

(References are available in detailed literature reports below)

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Haematology

Source Information SUMMARY:
General
  • In bears, haematology values are similar to those of the domestic dog. (B336.51.w51)
  • In one study of wild bears, bears captured by snaring had significantly higher leucocyte counts than culvert-trapped bears. (J40.41.w1)

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Biochemistry

Source Information SUMMARY:
General
  • In bears, biochemistry values are similar to those of the domestic dog. (B336.51.w51)
  • A study was carried out on the serum lipid concentrations in four ursid species and six canid species at four zoos; animals were immobilised and sampled after being fasted overnight. Findings for polar bears, (six bears sampled) were (mean +/- SEM): total cholesterol 8.9 +/- 0.76 mmol/L, triacylglyceride 2.91 +/- 0.484 mmol/L, HDL cholesterol 5.8 +/- 0.37 mmol/L and LDL cholesterol 6.8 +/- 1.49 mmol/L. The mean total cholesterol value was similar to that previously published for this species, and, along with values for Tremarctos ornatus - Spectacled bear, higher than that found in the other species, being at the high-end of mild elevation for cats and dogs. These bears also had high triacylglyceride and LDL cholesterol concentrations; the triacylglyceride values were similar to those reported previously for polar bears. (J2.35.w3)
  • A study of vitamins in serum of captive canids and ursids found the following concentrations in serum of one polar bear: retinol 667 ng/mL; retinyl palmitate trace, retinyl stearate trace, alpha-tocopherol 14.59 g/dL, phospholipids 4.78 mg/mL, cholesterol 2.23 mg/mL and triglicerides 2.47 mg/mL. Total vitamin A in the blood of the ursids tested was within the range of that found in other species. (J400.95.w1)
  • A study of vitamins in serum of captive canids and ursids at four North American zoos found the following concentrations in serum of five polar bears (mean +/- SEM): 25(OH)D 84 +/- 11.0 ng/mL; 1,25(OH)2D 18 +/- 4.2 ng/mL; retinol 25 +/- 1.8 g/dL; retinyl palmitate 4.9 +/- 1.3 g/dL; alpha-tocopherol 3362 +/- 156.2 g/dL; gamma-tocopherol 40 +/- 1.9 g/dL. Retinol concentrations were lower in the polar bears than in any other species tested. Retinyl stearate and gamma-tocopherol were not detected in brown bears, although they were detected in the three other bear species. 25(OHD and gamma-tocopherol were significantly higher in ursids than in canids, while retinol, retinyl palmitate and retinyl stearate were significantly lower in ursids than in canids. Both alpha-tocopherol and gamma-tocopherol were higher in polar bears and Tremarctos ornatus - Spectacled bear than in Ursus arctos - Brown bear and Helarctos malayanus - Sun bear. It was noted that multiple factors might affect the measured serum concentrations, including diet, gender, season, immobilisation procedure used, sample preparation method, activity, growth, pregnancy etc. (J400.128.w1)
  • A comparison of serum from captive and free-living polar bears found 25-hydroxyvitamin D (25-OH-D) levels were similar (348 +/- 215 nmol/L vs 360 +/- 135 nmol/L (captive vs. wild, mean +/- SD), but there were significant differences in serum retinol (1.37 +/- 0.67 mol/L vs. 1.89 +/- 0.63 mol/L P < 0.001) and alpha-tocopherol (18.56 +/- 18.56 mol/L vs. 48.76 +/- 13.92, P<0.001). It was considered that seal blubber was a likely source of these vitamins for free-living polar bears. (J54.17.w1)
  • Based on one to three blood samples from when cubs were in the den, and one after they exited the den, serum 25-OH-D3 increased from 108 +/- 37 nmol/L while cubs were in the den (seven samples) to 184.6 +/- 48.3 nmol/L (seven samples) in cubs which had emerged from the den; this was still lower than values for captive adults (348 +/- 215 nmol/L or free-ranging adults (360 +/- 135 nmol/L); 25-OHD3 levels were found to be correlated with age rather than in versus out of the den. It was considered that both exposure to UV-B in sunlight and intake of foods containing or supplemented with vitamin D3 may have contributed to the rise. Calcium and phosphate levels in serum were highest in denned cubs: calcium 2.9 +/- 0.4 mmol/L, phosphorus 3.1 +/- 0.5 mmol/L, versus calcium 2.5 +/- 0.1 mmol/L and phosphorus 2.4 +/- 0.4 mmol/L for cubs out of the den. Alkaline phosphatase, presumed to be the bone isoenzyme, was high in denned cubs, 831 +/- 426 IU/L (n=13), decreasing as cubs got older (96 +/- 83 IU/L, n = 13), for cubs which had exited the den. (J54.26.w1)

Effects of Age, Sex, Size and Body condition

  • During a study of apparently healthy free-ranging polar bears from Svalbard during August, the following were noted: (J1.38.w4)
    • Mean phosphorus was significantly higher in males than in females. (J1.38.w4)
    • Lipase was nearly twice as high in females as in males. (J1.38.w4)
    • Several values varied with age (comparing bears under six years of age with those in the 6 - 13 years group and with those older than 13 years of age): calcium and potassium both decreased slightly with age; ALP, CK and LDH all decreased with age; Albumin decreased in the oldest age group, globulin increased with age as did gamma-globulin. 
    • There were no significant differences in cortisol level with relation to age or sex. (J1.38.w4)
    • There were no significant changes in total protein with age, but total protein was higher in obese individuals than in lean individuals. It was also noted that total protein was lower than in captive bears, and showed greater variability. It was suggested that this difference might reflect the food availability of captive bears. (J1.38.w4)
  • For wild polar bears immobilized at Churchill, Manitoba, Canada, after being foot-snared or trapped in a culvert trap, alkaline phosphatase and calcium levels were significantly higher (P < 0.01 and P < 0.025) in cubs than in adults. (J40.41.w1)
Seasonal changes
  • During a study of apparently healthy free-ranging polar bears from Svalbard during August, it was noted that the urea:creatinine ratio varied from 4.5 to 44.9 (mean +/- SD 10.9 +/- 7.8). This ratio indicates that the bears, which were on land in summer, were fasting. (J1.38.w4)
  • For wild polar bears immobilized at Churchill, Manitoba, Canada, after being foot-snared or trapped in a culvert trap, blood glucose was significantly higher (P < 0.01) in November than in October. (J40.41.w1)
Effects of capture method
  • For wild polar bears immobilized at Churchill, Manitoba, Canada, after being foot-snared or trapped in a culvert trap, LDH and SGOT (AST) were significantly higher (P <0.001 for each enzyme) in foot-snared bears than in culvert-trapped bears. This was probably due to striated muscle trauma in the snared bears. (J40.41.w1)

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Authors & Referees

Authors Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referee Andrew Derocher (V.w100)

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