Effect of flight transport stress on blood parameters in beagles and the anti‐stress effect of dangshen

Abstract

Background

This study investigated the effect of flight transport stress on beagles' routine blood indexes and biochemical parameters and evaluated the anti‐stress effect of dangshen (Codonopsis pilosula).

Methods

We selected 12 beagles and divided them into two groups. One group was treated with dangshen decoction two hours before the flight, and the other group was untreated. Their routine blood indexes and clinical biochemical parameters were tested and analyzed before transport, after unloading and after adaptation for 1, 2, 3, 4, 5, and 6 days after administering dangshen.

Results

We found that flight transportation stress adversely influenced many of the beagles' routine blood indexes. These recovered during adaptation, with dangshen administration assisting recovery of most indexes. Flight transport stress also adversely influenced biochemical indexes in the beagles. Again these recovered during adaptation, and dangshen aided in the recovery.

Conclusion

Thus, we found that flight transport adversely affected the beagles' blood indexes, and dangshen reversed the damage from transport stress.

INTRODUCTION

Transportation stress is complex. During transport, in addition to the possibility of increased respiratory and heart rates, elevated body temperature, muscle tremors, enuresis, and vomiting, beagles can go into shock and collapse, altering routine blood and biochemical parameters. After transportation, beagles can adapt, and these levels can be restored to normal physiological levels. Research has shown that dangshen has numerous effects, such as alleviating radiation and fatigue, regulating blood sugar, enhancing immunity, increasing cardiac output, and improving ventricular systolic function and hypertension. This experiment tested the beagles' blood parameters after multiple stresses resulting from capture, crowding, heat, turbulence, acceleration and deceleration due to transport and dangshen decoction to study the blood index changes before and after transport and to explore the time required for adaptation after transportation and the anti‐stress effect to provide a basis for researching effective anti‐stress drugs.

METHODS

Laboratory animals

We randomly selected 12‐month‐old male beagles of similar weights (~10 kg), purchased from Zhenhe Laboratory Animal Co., Ltd, FuZhou (quality certification no. 35002100000051). Animal experiments were conducted in the Laboratory Animal Center of Guangzhou Military General Hospital. The animal experiment certificate number was 00113439, and the certificate number for experimental facility use was SYXK (Y) 2014‐0100. No clinical abnormalities were observed before the experiment, canine distemper checks were negative, and breeding was conventionally managed.

Reagents

Biochemical reagents included a C‐reactive protein (CRP) quantitative determination kit, lot no. 20150412; alanine aminotransferase (ALT) kit, lot no. 20150322; aspartate aminotransferase (AST) kit, lot no. 20150122; triglyceride kit (TG), lot no. 20150112; total cholesterol kit (COHL), lot no. 20141212; blood glucose kit, lot no. 20150312; total protein (TP) kit, lot no. 20150222; creatine kinase (CK) kit, lot no. 20150322; α‐amylase (AMYL) kit, lot no. 20150112; albumin (ALB) kit, lot no. 20150322; urea nitrogen (UREA) kit, lot no. 20141212; creatinine (CREA) kit, lot no. 20150312; uric acid (UA) kit, lot no. 20150122; and multiterm untreated material 2, lot no. kk097. All materials were purchased from Shanghai Kehua Bio‐Engineering Co., Ltd.

Routine blood examination reagents included diluent, lot no. D15042301; hemolytic agent, lot no. L14102301; cleaning fluid, lot no. C15050401; and wash concentrate, lot no. C15020301. All materials were purchased from Bio Lab Medical (Guangzhou) Co., Ltd.

Instruments and equipment

Equipment included the Hitachi 7060 fully automated biochemical analyzer (Japan), the ABX VetABC fully automated hemanalysis instrument (France), and the LGR‐WSD20 automatic temperature and humidity recorder from Hangzhou Loggertech Co., Ltd.

Experimental method

Twelve approximately 12‐month‐old beagles (10 kg) were selected and marked with row numbers while on full stomachs. Their health conditions were checked before transportation to identify any clinical symptoms. The beagles were divided into two groups of 6 animals each. One group received 20 mL of dangshen decoction (from 28 g dangshen and water) two hours before the flight, and the other group remained untreated.

An automatic temperature and humidity recorder was used to record temperature and humidity changes during transport. The beagles' loading densities were approximately 2/m². Seven milliliters of venous blood was drawn from the hindlimbs of all dogs at 5:00 am on the day of transport, 5 mL of which were put into non‐anticoagulative test tubes to separate the serum by centrifugation; biochemical tests were conducted within the prescribed time; and 2 mL of blood was put into test tubes containing EDTA‐K2 anticoagulative agent and shaken evenly for routine blood examination. At 6:21 am, the beagles were transported to the airport in a single‐layer bus, arriving at Fuzhou Changle International Airport at 7:36 am, departing from the airport at 11:40 am, arriving at Guangzhou Baiyun International Airport at 13:00, arriving at the China Southern Airlines Guangzhou Airport warehouse at 15:00, departing from the warehouse at 20:30, and finally arriving at the laboratory on a single‐layer bus at 22:36. At this time, they were given a small dose of normal saline, and their blood was sampled before transportation at 22:50. They were adaptively maintained for 6 days, during which time blood samples were drawn at the same time daily (22:50) for blood and biochemical testing.

Blood parameters examined

The blood parameters examined included blood platelets (PLT), mean platelet volume (MPV), red blood cells (RBC), hemoglobin (HGB), hematocrit value (HCT), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), red blood cell distribution width (RDW), white blood cells (WBC), monocyte absolute value (MON#), lymphocyte percentage (LYM%), neutrophilic absolute value (GRA#), monocyte percentage (MON%), lymphocyte absolute value (LYM#) and neutrophil percentage (GRA%).

Biochemical parameters examined

The biochemical parameters examined included alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein (TP), albumin (ALB), blood glucose (GLU), globulin (GLO), C‐reactive protein (CRP), uric acid (UA), urea (UREA), amylase (AMY), creatinine (CREA), triglycerides (TG), total cholesterol (COHL) and creatine kinase (CK).

Statistical analysis

Experimental data were statistically analyzed by SPSS 17.0, and the results are shown as the mean ± standard deviation. Variance was analyzed by repeated measurements of a single factor to compare untreated group data before and after transport and by repeated measurements of double factors to compare the untreated and test group data. To further compare pairs, the LSD test was used for equal variances, and Dunnett's T3 test was used for unequal variances.

RESULTS AND DISCUSSION

Temperature and humidity on the test flight

Ambient temperature varied from 26.1°C to 38.6°C and the humidity ranged from 53.8% to 100% during the test period. The temperature curve over time is shown in Figure  (temperature, °C, time, min), and the humidity curve over time is shown in Figure  (humidity, %, time, min).

Blood examination and biochemical index test results

Routine blood and biochemical index test results before and after transportation and after 6 days of adaptation are shown in Tables  and .

Routine blood test results

Index	Before stressing	After stressing 0 h	Breeding for 1d	2d	3d	4d	5d	6d
WBC/(109/L) Blank	5.82 ± 1.05	6.75 ± 1.66	8.40 ± 1.37**	7.35 ± 1.27*	7.33 ± 1.53	8.68 ± 2.37*	7.40 ± 0.85*	6.15 ± 0.55
Fed group	6.93 ± 0.44□	9.57 ± 1.99	6.50 ± 1.51■	6.72 ± 1.59	6.95 ± 2.29	10.88 ± 4.77	7.45 ± 0.83	7.45 ± 0.83
RBC (1012/L) Blank	6.92 ± 0.39	8.16 ± 0.65**	7.36 ± 0.38*	7.30 ± 0.21*	7.44 ± 0.27*	7.65 ± 0.94	7.28 ± 0.85	6.84 ± 0.56
Fed group	9.74 ± 1.45■	7.57 ± 0.67	7.53 ± 0.70	6.94 ± 0.29	7.44 ± 2.52	6.92 ± 0.50	7.66 ± 1.27	11.16 ± 0.95■
HGB (g/L) Blank	135 ± 10	165 ± 13**	156 ± 9**	158 ± 12**	161 ± 8**	163 ± 17*	146 ± 5*	132 ± 20
Fed group	187 ± 37□	159 ± 8	156 ± 19	145 ± 8□	158 ± 52	147 ± 10	163 ± 17	234 ± 19■
HCT (L/L) Blank	410 ± 38	526 ± 52**	468 ± 25*	473 ± 38*	473 ± 23**	448 ± 32	453 ± 47	409 ± 66
Fed group	591 ± 152□	480 ± 28	473 ± 57	435 ± 19	455 ± 152	425 ± 29	465 ± 53	697 ± 45■
PLT (109/L) Blank	335.5 ± 42.1	228.3 ± 87.2*	302.0 ± 66.7	255.7 ± 112.3	281.2 ± 59.0*	309.0 ± 47.3	313.0 ± 81.6	333.7 ± 40.0
Fed group	282.7 ± 132.6	251.7 ± 42.4	262.5 ± 84.2	277.8 ± 128.4	258.2 ± 124.0	303.2 ± 72.1	262.3 ± 65.3	127.2 ± 85.8■
MCV (Fl) Blank	59.7 ± 3.0	64.3 ± 1.8**	63.7 ± 1.5**	63.7 ± 2.1**	63.7 ± 1.5**	62.5 ± 1.6	62.3 ± 1.4*	62.0 ± 2.2
Fed group	61.5 ± 5.8	63.7 ± 3.4	62.8 ± 3.7	62.7 ± 3.5	61.3 ± 3.7	61.3 ± 3.1	61.3 ± 2.9	62.5 ± 4.0
MCH (pg) Blank	19.12 ± 0.71	20.28 ± 0.75*	21.2 ± 0.75**	21.2 ± 0.96**	21.7 ± 0.59**	21.3 ± 0.73**	21.5 ± 0.73**	21.1 ± 0.62**
Fed group	19.58 ± 1.27	21.10 ± 1.39	20.72 ± 1.36	20.83 ± 1.34	21.45 ± 1.38	21.22 ± 1.40	21.40 ± 1.49	20.97 ± 1.34
MCHC (g/L) Blank	318.3 ± 9.7	323.1 ± 7.9	332.8 ± 5.0*	332.7 ± 9.1*	340.7 ± 2.5**	341.5 ± 6.3**	345.2 ± 5.5**	336.0 ± 7.5**
Fed group	319.2 ± 13.8	331.8 ± 5.6	330.3 ± 4.5	332.0 ± 5.9	349.0 ± 5.1■	344.8 ± 8.8	350.7 ± 10.5	334.8 ± 7.4
RDW % Blank	11.37 ± 1.34	14.85 ± 0.36**	14.41 ± 0.62**	14.15 ± 1.19**	13.88 ± 0.44*	11.78 ± 0.76	11.95 ± 0.78	12.48 ± 0.84
Fed group	13.57 ± 2.49	15.12 ± 1.13	14.72 ± 1.35	14.65 ± 1.36	11.88 ± 0.87■	12.67 ± 2.45	12.83 ± 1.40	12.65 ± 1.19
MPV (Fl) Blank	9.33 ± 1.01	9.07 ± 0.51	8.40 ± 0.98**	8.75 ± 0.73	8.77 ± 1.11	8.72 ± 0.83	8.62 ± 0.83*	10.03 ± 2.19
Fed group	11.62 ± 1.89	9.70 ± 1.03	8.75 ± 1.15	8.83 ± 1.28	9.73 ± 1.36	9.17 ± 1.02	10.07 ± 2.12	11.98 ± 2.48
LYM% Blank	67.6 ± 3.6	64.0 ± 4.1	58.0 ± 5.7**	57.2 ± 4.7**	62.5 ± 4.0*	63.1 ± 4.2**	65.6 ± 4.6	68.3 ± 2.9
Fed group	61.0 ± 4.2	58.8 ± 3.4□	61.3 ± 3.4	59.5 ± 3.5	61.6 ± 2.5	61.2 ± 3.4	63.5 ± 6.5	56.5 ± 7.4□
MON% Blank	9.33 ± 0.96	11.18 ± 1.38*	12.57 ± 1.28**	12.55 ± 1.57**	12.53 ± 0.71**	12.57 ± 0.89**	12.08 ± 1.35*	10.85 ± 1.33
Fed group	11.27 ± 2.07	13.22 ± 0.56□	10.80 ± 1.48	11.30 ± 0.76	11.57 ± 1.46	12.45 ± 1.30	11.03 ± 1.38□	13.45 ± 0.69■
GRA% Blank	23.05 ± 2.77	24.85 ± 3.03	29.43 ± 4.97**	30.25 ± 3.33**	24.98 ± 4.12	24.33 ± 3.49	22.37 ± 3.38	20.90 ± 3.10
Fed group	27.73 ± 4.09	27.97 ± 2.99	27.90 ± 4.07	29.20 ± 4.01	26.80 ± 2.89	26.32 ± 3.32	25.47 ± 5.67	30.05 ± 7.40□
LYM# Blank	3.90 ± 0.72	4.23 ± 0.90	4.78 ± 0.69**	4.17 ± 0.97	4.62 ± 0.99*	5.38 ± 1.30*	5.17 ± 0.81**	4.42 ± 1.11
Fed group	4.25 ± 0.46	5.57 ± 1.07	3.90 ± 0.86■	3.93 ± 0.82	4.25 ± 1.47	6.53 ± 2.71	4.67 ± 0.58	3.50 ± 0.93
MON# Blank	0.52 ± 0.17	0.72 ± 0.30	1.02 ± 0.26**	0.88 ± 0.15**	0.82 ± 0.23	1.05 ± 0.37**	0.92 ± 0.25*	0.75 ± 0.15
Fed group	0.75 ± 0.10	1.23 ± 0.29□	0.63 ± 0.10■	0.70 ± 0.15	0.77 ± 0.27	1.33 ± 0.72	0.77 ± 0.20	0.80 ± 0.28
GRA# Blank	1.52 ± 0.39	1.78 ± 0.54	2.57 ± 0.67**	2.27 ± 0.31**	1.88 ± 0.52	2.23 ± 0.82*	1.87 ± 0.39	1.50 ± 0.35
Fed group	2.05 ± 0.31	2.77 ± 0.73□	1.97 ± 0.64■	2.08 ± 0.73	1.93 ± 0.61	3.02 ± 1.39	2.02 ± 0.50	2.07 ± 0.82

*P < .05, **P < .01, compared with the Untreated group before stressing; ^□P < .05, ^■P < .01, compared with the Untreated group at the same time point.

Biochemical index test results

Index	Before stressing	After stressing 0 h	Breeding for 1d	2d	3d	4d	5d	6d
AMY (U/L) Blank	867.3 ± 113.4	640.3 ± 114.3*	482.5 ± 116.1**	384.0 ± 61.0**	423.3 ± 62.0**	622.0 ± 70.7**	831.7 ± 46.8	871.3 ± 45.8
Fed group	922.2 ± 107.3	515.3 ± 149.6	457.0 ± 149.6	452.0 ± 197.9	602.2 ± 115.1■	851.7 ± 142.0□	932.5 ± 113.6	941.3 ± 105.7
ALT (U/L) Blank	37.7 ± 12.8	43.7 ± 7.5	19.3 ± 7.7*	17.3 ± 11.3*	15.5 ± 6.9*	25.2 ± 8.8	34.8 ± 10.6	36.5 ± 7.3
Fed group	30.8 ± 11.8	39.5 ± 14.7	30.0 ± 18.0	23.2 ± 9.6	18.2 ± 4.4	26.8 ± 8.6	31.5 ± 9.0	33.2 ± 6.7
AST (U/L) Blank	40.0 ± 4.1	35.2 ± 5.6	29.0 ± 7.6*	9.5 ± 5.2**	15.5 ± 6.9**	19.3 ± 4.9**	35.3 ± 6.8	40.2 ± 7.4
Fed group	46.0 ± 9.4	31.7 ± 13.8	24.3 ± 6.3	19.0 ± 3.3■	24.3 ± 6.3□	31.7 ± 9.1■	41.0 ± 6.4	39.3 ± 5.2
TP (g/L) Blank	70.8 ± 3.6	56.4 ± 4.3**	40.6 ± 6.2**	31.1 ± 6.4**	31.2 ± 4.3**	46.1 ± 5.3**	64.4 ± 4.4	69.5 ± 5.8
Fed group	71.9 ± 5.9	62.3 ± 5.3■	36.4 ± 7.7	32.4 ± 6.5	30.7 ± 5.9	50.9 ± 5.5	72.1 ± 6.8	70.0 ± 6.4
ALB(g/L) Blank	34.5 ± 1.5	26.1 ± 2.9**	18.9 ± 2.5**	14.1 ± 2.5**	15.1 ± 2.5**	17.9 ± 2.5**	31.1 ± 2.9	34.3 ± 1.7
Fed group	35.4 ± 1.7	33.4 ± 1.7■	17.4 ± 3.5	14.9 ± 3.3	16.3 ± 3.8	19.4 ± 1.7	34.5 ± 1.8	33.5 ± 1.5
GLU (mmol/L) Blank	4.10 ± 0.58	1.32 ± 0.41**	2.20 ± 0.52**	1.55 ± 0.23**	1.45 ± 0.28**	1.92 ± 0.60**	3.6 ± 0.58	4.0 ± 0.63
Fed group	4.37 ± 0.45	1.48 ± 0.34	2.45 ± 0.21	1.95 ± 0.42	2.80 ± 0.36■	3.45 ± 0.34■	4.33 ± 0.35□	4.37 ± 0.44
UREA (mmol/L) Blank	6.60 ± 1.29	5.94 ± 1.19	4.31 ± 1.15**	2.77 ± 0.77*	2.29 ± 0.78*	3.92 ± 1.20*	5.50 ± 1.08	6.44 ± 0.89
Fed group	8.07 ± 0.92	6.19 ± 1.87	4.45 ± 1.56	3.00 ± 1.17	4.84 ± 1.24■	5.94 ± 0.78□	7.32 ± 0.91□	6.75 ± 1.35
CREA (umol/L) Blank	81.5 ± 4.5	47.8 ± 6.4**	44.5 ± 6.6**	32.8 ± 6.1**	26.8 ± 5.3**	37.7 ± 6.1**	63.5 ± 7.4**	79.3 ± 5.2
Fed group	79.8 ± 8.4	43.3 ± 4.4	41.8 ± 8.0	35.7 ± 8.8	28.5 ± 7.5	40.7 ± 6.4	71.0 ± 5.4	77.3 ± 4.1
UA (umol/L) Blank	26.3 ± 3.8	24.7 ± 4.9	18.2 ± 4.8**	17.5 ± 4.2*	15.2 ± 3.4**	12.7 ± 4.2**	22.5 ± 5.0**	25.5 ± 5.2
Fed group	24.0 ± 4.9	22.7 ± 2.2	14.8 ± 4.9	18.7 ± 5.6	11.0 ± 4.0	10.3 ± 2.5	21.3 ± 5.2	25.2 ± 3.2
CHOL (mmol/L) Blank	4.46 ± 0.78	3.81 ± 0.84	2.85 ± 0.86*	2.11 ± 0.42**	2.34 ± 0.62**	3.23 ± 0.78	4.11 ± 0.51	4.54 ± 0.76
Fed group	4.60 ± 0.83	2.90 ± 0.65■	2.44 ± 0.77	2.16 ± 0.45	2.24 ± 0.40	2.92 ± 0.71	4.32 ± 0.74	4.29 ± 0.62
TG (mmol/L) Blank	0.41 ± 0.10	0.45 ± 0.10	0.39 ± 0.07	0.51 ± 0.21	0.58 ± 0.09*	0.50 ± 0.06*	0.43 ± 0.08	0.43 ± 0.07
Fed group	0.41 ± 0.09	0.41 ± 0.10	0.41 ± 0.10	0.55 ± 0.27	0.49 ± 0.12	0.44 ± 0.11	0.45 ± 0.11	0.50 ± 0.09
CK (U/L) Blank	9.83 ± 3.06	258.67 ± 46.70**	180.00 ± 72.97**	100.00 ± 22.80**	64.00 ± 16.19**	95.33 ± 15.19**	70.33 ± 9.46**	86.33 ± 12.58**
Fed group	17.83 ± 8.03□	164.17 ± 95.78□	149.17 ± 154.97	104.50 ± 66.12	67.17 ± 20.79	98.17 ± 12.62	78.67 ± 9.05■	87.67 ± 9.75
GLOB (g/L) Blank	36.2 ± 3.6	30.3 ± 3.4*	21.7 ± 4.7**	17.0 ± 5.0**	16.1 ± 4.4**	28.2 ± 3.5**	33.3 ± 3.0	35.2 ± 4.9
Fed group	36.5 ± 4.8	28.9 ± 4.0	19.0 ± 4.5	17.5 ± 3.7	14.35 ± 3.26	31.45 ± 4.29	37.55 ± 5.63	36.52 ± 5.23
CRP (mg/L) Blank	0.50 ± 0.18	0.42 ± 0.17	0.47 ± 0.19	0.57 ± 0.23	0.52 ± 0.17	0.47 ± 0.16	0.53 ± 0.18	0.50 ± 0.19
Fed group	0.57 ± 0.15	0.57 ± 0.08	0.40 ± 0.09	0.63 ± 0.12	0.57 ± 0.12	0.53 ± 0.14	0.55 ± 0.14	0.57 ± 0.08

*P < .05, **P < .01, compared with the Untreated group before stressing; ^□P < .05, ^■P < .01, compared with the Untreated group at the same time point.

Effect of flight transport stress on routine blood parameters in beagles and the anti‐stress effect of dangshen

Compared with the value before transportation, MON% in beagles was significantly higher (P < .05) after transport at 0 h. WBC, GRA%, LYM#, MON# and GRA# were higher, but not significantly (P > .05), reflecting the body's physiological or pathological reaction on an empty stomach and under transportation stress. The WBC change indicated that the body's immune system was not obviously damaged. WBC, GRA%, LYM#, MON# and GRA# were significantly higher (P < .01) after adaptation for 1 day. LYM# showed no significant difference after adaptation for 2 days; MON# and GRA# showed no significant difference after adaptation for 3 days; WBCs showed no significant difference after adaptation for 6 days; and LYM% was lower after transport. These results reflected a possible compensatory immune response in the animals to various complex stresses, as suggested by the significantly lower PLT value.

Compared with the values before transport, MCH was significantly higher (P < .05) after transport at 0 h. RBC, HGB, HCT, MCV and RDW were much higher (P < .01) and MCHC was higher but not to a significant level (P > .05), showing that during flight transport, fasting and water deprivation in animals can lead to dehydration and concentrated plasma or that the body's metabolism is enhanced because of the inappropriate environment or other body stressors, resulting in manic vexation or excessive excitement of the beagles. MCH and MCHC remained much higher (P < .01) after adaptation for 6 days, showing that beagles' blood cells take a long time to recover after flight transport stress.

Compared with the untreated group before transport, WBCs in the treated group were significantly higher (P < .05), LYM% was significantly lower (P < .05), and LYM#, GRA%, MON# and GRA# were higher but not significantly (P > .05). LYM% was lower, but not significantly (P > .05), indicating that the beagles reacted defensively to the flight transport stress and that their immunity was enhanced after being treated with dangshen; thus, the intervention counteracted the negative effects of transport on the steady‐state immune system parameters.

Compared with the untreated group before transport, HGB and HCT in the treated group were significantly higher (P < .05), RBCs were much higher (P < .01), and MCV, MCH, MCHC, RDW and MPV were higher but not significantly (P > .05). This result shows that dangshen promoted hematopoiesis to enhance red blood cell function. RBC, HGB and HCT remained significantly higher (P < .01) after adaptation for 6 days, while PLT was significantly lower (P < .01), showing that dangshen replenished the blood and inhibited platelet aggregation.

After an adaptation period, the index changes in the two beagle groups showed that dangshen enhanced the beagles' immunity and blood function and improved the body's recovery from damage.

Effect of flight transport stress on blood biochemical indexes and dangshen's anti‐stress effect

The beagles' biochemical index results before and after transport showed that flight transport stress, when the beagles were fasted and deprived of water, had an adverse effect because CK was significantly higher (P < .01) after transport than before transport and after adaptation for 6 days. This result indicated that flight transport stress damaged the muscle cell membrane system in the beagles, which remained incompletely recovered after adaptive breathing for 6 days. During index testing, CK in the treated group was significantly higher than that in the untreated group before transportation and significantly lower after transport at 0 h and after adaptation for 5 days, showing that dangshen enhanced the body's metabolism and promoted recovery from muscle damage. Transport stress caused the beagles to move in an agitated manner, resulting in oxygen deficit in the tissues and organs and increased liver cell membrane permeability and necrosis, thus causing the release of AST and ALT from the cells. During the experiment, after transport, all the beagles' serum AST levels were within the normal range but had significantly decreased (P < .05), while ALT was slightly increased but did not significantly differ (P > .05) from that before stress. AST and ALT can reflect the degree of liver cell damage, as ALT mainly exists in the liver cells and can be increased when liver cells have mild lesions, whereas AST mainly exists in the mitochondria and cytoplasm and can be released when mitochondria rupture after liver cell damage. Therefore, we believe that greater stimulation (eg, capture and restraint during blood collection) caused the beagles' serum AST and ALT concentrations to increase before transport, and subsequent transport stress had less effect on liver function, without seriously damaging the liver cells. Therefore, ALT was elevated, and AST was gradually restored. Compared with the untreated group, the treated group's AST and ALT levels recovered faster, showing that dangshen reduced liver function damage during transportation and promoted liver function recovery.

ALB and TP maintain osmotic pressure within the blood vessels and play roles as vegetative cells. They are produced by the liver; thus, when liver function is damaged, they subsequently decrease, and the degree of reduction positively correlates with the degree of liver damage. During the experiment, TP and ALB were significantly lower (P < .01) after transport than before transport at 0 h, showing that flight transport stress damaged the beagles' livers. After adaptation for 5 days, TP and ALB did not differ significantly, showing that the liver damage was gradually restored after an adaptive period. The results also showed that ALB and TP in the treated group were higher than those in the untreated group, showing that dangshen promoted liver injury repair.

GLU was significantly lower after transport than before, which was inconsistent with Jinjin Han's results, possibly due to the implementation of fasting during transport to prohibit the animals from obtaining outside nutritional supplements. Thus, GLU declined significantly after transport, which likely prompted the body's nutritional reserves to be excessively consumed. GLU did not significantly differ after adaptation for 5 days, showing that the body only slowly returns to normal after transport stress. Compared with the untreated group, the treated group's GLU was higher (P > .05) before transport, much higher (P < .01) after adaptive breathing for 3 and 4 days, and significantly higher (P < .05) after adaptive breathing for 5 days, indicating that dangshen reduced damage to the beagles' spleen and stomach function caused by transport stress and promoted recovery of digestion and absorption function, thereby returning the blood sugar level to normal.

In this experiment, after stress, CREA, UREA and UA first decreased and then increased to the same level as that before stress, showing that inadequate nutritional intake during flight transport stress results in malnutrition, dehydration and other symptoms in beagles, as well as damaged renal functions. During subsequent adaptation, glomerular filtration function recovered slowly. The treated group's UREA was higher than that of the untreated group, showing that dangshen can improve the body's energy reserves and reduce the kidney function damage caused by stress.

ACKNOWLEDGEMENTS

This work was financially supported by the Science and Technology Planning Project of the Guangdong Science and Technology Department (2015A030302073).

CONFLICTS OF INTEREST

None.

AUTHOR CONTRIBUTIONS

WL and XW conceived and designed the study; LYZ, CXY and XXG carried out experimental work and data analysis; WL, LYZ and CXY wrote the initial draft. All authors contributed to revising the manuscript. All authors gave final approval for publication.