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Biochemical Reference Intervals for Semi-Captive Sloth Bears (Melursus ursinus ursinus) in India

Chandra Mohan S. Sooraj V. Nair Reena Gupta Karikalan M. Ilayaraja S. Arun Attur Shanmugam Anil Kumar Sharma
Vol8(4), 311-315

Blood samples were collected in serum vials from 30 adult sloth bears of either sex, being maintained at Agra Bear Rescue Centre of Wildlife SOS, India. Serum was separated and 12 major serum biochemical parameters were analyzed. All the parameters were estimated manually using chemical methods. The mean total protein concentration was 7.32±1.05 g/dl. Alanine aminotransferase and aspartate aminotransferase activities were 36.78±7.52 U/L and 56.37±27.02 U/L respectively. Renal functions tests like creatinine, urea and BUN were at 1.08±0.24 mg/dl, 13.4±2.74 mg/dl and 6.24±1.49 mg/dl respectively. The mean calcium and phosphorus concentrations were 9.48±1.45 mg/dl and 3.7±0.53 mg/dl respectively. Concentrations of serum electrolytes sodium, potassium and chloride were 72.44±15.84 mmol/L, 5.07±0.78 mmol/L and 83.54±13.8 mmol/L respectively. Concentration of triglycerides was at 330.29±137.9 mg/dl. As many internal and external factors influence the parameters, with careful interpretation these reference intervals play very crucial role in monitoring health condition of sloth bear.

Keywords : Biochemistry Reference Intervals Sloth Bear Serum


From human to animals hematological and serum biochemical parameters play pivotal role in assessing health status. In this context establishment of biochemical reference intervals is very crucial. Sloth bear (Melursus ursinus ursinus), a member of family Ursidae is native to the Indian subcontinent. Due to continuing loss of habitat and poaching the population has reduced drastically. Sloth bears have also been used as pets due to their tameable nature (Servheen et al., 1999). As the population is gradually declining, the animal has been listed as vulnerable under the IUCN red list (IUCN 2016). In India, Wildlife SOS is playing very important role in conservation of species from human exploitation and poaching for Chinese medicine ( Reference intervals for major hematological parameters have been generated in an earlier study (Shanmugam et al., 2008). Reference intervals for serum biochemical parameters have been reported by two studies conducted on 3 (1 male and 2 females) and 11 (5 males and 6 females) sloth bears by Bush and Smith (1980) and Veeraselvam et al. (2014) respectively. Due to difficulty in the sample collection study of a large population on large population is still lacking and mostly unfeasible. In the present study was conducted on 35 sloth bears and reference intervals for major serum biochemical parameters have been generated which may be used in future for regular health monitoring or post therapeutic health assessment. As conservation of animals under captivity is taking place, regular monitoring of health also gaining its importance.

Materials and Methods

Animals of either sex (n=35) were restrained chemically with xylazine and ketamine at 2mg/kg and 5mg/kg body weight respectively. Blood samples were collected from the jugular vein and serum was separated. Samples were brought to the laboratory under cold chain. All the biochemical parameters were estimated manually as soon as possible using commercial kits (Coral Clinical Systems) as per manufacturer’s instructions. Data was analyzed with Microsoft excel version 2012 and 95% confidence intervals were generated as per Walton (2001).

Results and Discussion

In total 12 major serum biochemical parameters were analyzed in the present study. The values for mean, standard deviation and 95% confidence interval are presented in Table 1. As there are only few studies conducted on sloth bears, data have been compared with the two studies on sloth bear (Bush and Smith 1980; Veeraselvam et al., 2014) and other members of Ursidae family like brown bear at Sweden and Croatia (Graesli et al., 2014), black bears (Hellgren et al., 1993), Andean bears (Castellanos et al., 2010) and polar bear (Tryland et al., 2002). Mean value of serum total protein was 7.32±1.05 g/dl is similar to the values reported by Bush and Smith (1980) (7.9±0.2 g/dl) and Veeraslvam et al. (2014) (6.8±0.3 g/dl) for sloth bear. Total protein is also similar to the concentration reported in Andean bear (7.73 g/dl), polar bear (7.6±0.6 g/dl) but the lower limit reported for brown bear (4.8-7.2 g/dl) is very low, this could be due to the effect of diet or underlying diseases. Total protein concentration is also known to provide information on protein deficiency disorders/diseases and dehydration status. ALT and AST are two common enzymes used to assess liver or muscle damage. The mean ALT concentration (Table 1) is much lower compared to report on sloth bear viz. 103.5±1.9 U/L by Bush and Smith (1980) this could be due to  muscle damage or very small number of animals (n=3) used for the study.

Table 1: Serum biochemical parameters of sloth bear.  avalues for the parameters recorded in brown bear, Andean bear and polar bear were converted from mmol/L to mg/dl etc. using conversion factors (calcium 0.2495, creatinine 88.42, urea nitrogen 0.3571 and triglycerides 0.0113) for interpretation under discussion

S. No. Parameter Mean Standard Deviation 95% Confidence Interval
1 Total protein (g/dl) 7.32 1.05 6.97-7.6
2 ALT (U/L) 36.78 7.52 34.3-39.3
3 AST (U/L) 56.37 27.02 47.4-65.3
4 Creatinine (mg/dl) 1.08a 0.24 1.0-1.15
5 Urea (mg/dl) 13.4 2.74 12.4-14.30
6 BUN (mg/dl) 6.24a 1.49 5.7-6.7
7 Calcium (mg/dl) 9.48a 1.45 8.9-9.96
8 Phosphorus (mg/dl) 3.78a 0.53 3.6-3.95
9 Sodium (mmol/L) 72.44 15.84 67.1-77.6
10 Potassium (mmol/L) 5.07 0.78 4.81-5.3
11 Chloride (mmol/L) 83.54 13.8 78.97-88.1
12 Triglycerides (mg/dl) 330.29a 137.9 284.6-375.9

But the value is similar to the concentration as found in brown bear (11-47 U/L) but much higher than Andean bear (21.43±19.41 U/L) though the range falls within. ALT value is also higher than 24±9 U/L in polar bear. As like ALT, concentration of AST was also alos much lower than 125±14.0 U/L reported by Veeraselvam et al. (2014) but the value falls within the lower limit of brown bear (45-215 U/L), almost similar to Andean bear (30.23±20.68 U/L) and polar bear (67±37 U/L). This could be due to factors like tissue damage, chronic diseases.

Creatinine, urea and BUN are being used to assess renal function both in humans and animals. Mean creatinine concentration in sloth bear was 1.08±0.24 mg/dl which is similar to an earlier report on sloth bear (1.24±0.09 mg/dl by Veeraselvam et al., 2014), in brown bear (0.77-2.46 mg/dl) and polar bear (1.21±0.25 mg/dl). But the upper limit 2.46mg/dl recorded in brown bear is quite higher compared to sloth bear. This could be due to dietary influence, as brown bear do consume fish in contrary to sloth bear where carbohydrate comprised as main dietary component under captivity. Similarly urea and BUN values of sloth bear are much lower to the values reported earlier 18.3±4.0 mg/dl by Bush and Smith (1980) and 19.08±0.55mg/dl by Veeraselvam et al. (2014). This could be due to dietary influence. But values are in corroboration with brown bear, Andean bear (BUN 13.35±4.39 mg/dl), polar bear and black bear. As with Creatinine, urea nitrogen values also influenced by animal dietary and age factors.

It is well known about the importance of calcium and phosphorus in bone growth and other sensory functions. The mean calcium and phosphorus values for sloth bear were 9.48±1.45mg/dl and 3.79±0.53 mg/dl respectively (Table 1). The values are in corroboration with earlier studies 9.6±0.8mg/dl calcium and 5.3±1.4mg/dl phosphorus by Bush and Smith (1980) and .47±0.29 mg/dl calcium, 5.11±0.15 mg/dl phosphorus by Veraselvam et al. (2014). Both diet and age factors also influence the serum calcium and phosphorus concentration. Serum electrolytes like sodium, potassium and chloride play crucial role in monitoring health status of the animal. These parameters also assayed along with creatinine and BUN to assess renal function and electrolytes are very good indicators of the state of hydration. In the present study concentration of sodium, potassium and chloride were 72.44±15.84 mmol/L, 5.07±0.78 mmol/L and 83.55±13.8 mmol/L respectively. Only one report is available for sloth bear in terms of electrolytes. The sodium and chloride concentrations were much lower compared to 136.6±5.6mmol/L sodium and 102.8±2.8 mmol/L by Bush and Smith (1980) but potassium concentration is in corroboration. Same trend has been observed with studies on other bear specie viz. brown bear (128-141 mmol/L sodium) and polar bear (138±5.4 mmol/L sodium). Unlike sodium chloride concentration fell within range recorded for brown bear (88-104 mmol/L) and polar bear (100±3.6 mmol/L). As lot many factors affect the concentration of electrolytes it is difficult to correlate with particular reason.

Concentration of serum triglycerides varied too widely in sloth bear from 97.87-563.8 mg/dl. The same trend has also been observed in other species viz. brown bear (150.44-477.87 mg/dl), Andean bear (648.67±145.13 mg/dl), polar bear (238.93±79.64 mg/dl) and black bear (169±48 mg/dl). This could be due to diet and seasonal variation as the earlier study on sloth bear indicated that triglyceride concentration varies with season and diet (Shanmugam et al., 2011). As all most all the parameters are being influenced by many internal and external factors a careful judgment can yield good interpretation regarding health status of the animal.


The authors are greatly thankful to the Director of the Indian Veterinary Research Institute, Izatnagar for providing necessary facilities to carry out the work and thanks to Wildlife SOS staffs for all co operations.


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