Peri-operative body temperatures in isoflurane-anaesthetized rabbits following ketamine-midazolam or ketamine-medetomidine

OBJECTIVE: To investigate alterations in peri-operative body temperatures and oesophageal-skin temperatures in isoflurane-anaesthetized rabbits following either ketamine-midazolam or ketamine-medetomidine induction of anaesthesia. ANIMAL POPULATION: Fifty client-owned rabbits, (25 male, 25 female) of different breeds anaesthetized for elective neutering (age range: 3-42 months; mass range: 1.15-4.3 kg). STUDY DESIGN: Randomized, blinded clinical study. METHODS: Pre-anaesthetic rectal temperature was measured. A 24 SWG catheter was placed in a marginal ear vein after local anaesthesia. Ketamine (15 mg kg(-1)) with medetomidine (0.25 mg kg(-1)) (group KMT) or with midazolam (3 mg kg(-1)) (group KMZ) was injected intramuscularly (IM). Following endotracheal intubation anaesthesia was maintained with isoflurane in oxygen. Carprofen (3 mg kg(-1)) and glucose saline (5 mL kg(-1) hour(-1)) were administered through the intravenous catheter. Room temperature and humidity, skin temperature (from tip of pinna) and oesophageal temperature were measured during anaesthesia. Ovariohysterectomy or castration was performed. Rectal temperature was taken when isoflurane was discontinued (time zero) and 30, 60 and 120 minutes thereafter. Atipamezole (0.5 mg kg(-1)) was administered IM to rabbits in group KMT at zero plus 30 minutes. Mass, averaged room temperature and duration of anaesthesia data were compared using a two-tailed t-test. Age, averaged room humidity, rectal temperature decrease, oesophageal temperature decrease and oesophageal-skin difference data were compared using a Kruskal-Wallis test. p < 0.05 was considered significant. RESULTS: The averaged oesophageal-skin temperature difference was significantly greater in group KMT [median 9.85 degrees C (range 6.42-13.85 degrees C)] than in group KMZ [4.38 degrees C (2.83-10.43 degrees C)]. Rectal temperature decreased over the anaesthetic period was not significantly different between the two groups; however, oesophageal temperature decrease was significantly less in group KMT [1.1 degrees C (-0.1-+2.7 degrees C)] than in group KMZ [1.4 degrees C (0.6-3.1 degrees C)]. CONCLUSIONS: Oesophageal-skin temperature difference is larger in rabbits anaesthetized with ketamine-medetomidine combination than ketamine-midazolam. CLINICAL RELEVANCE: The oesophageal temperature in rabbits anaesthetized with ketamine-medetomidine and isoflurane decreases significantly less than in animals anaesthetized with ketamine-midazolam and isoflurane, during anaesthesia.     

Hyperthermia in the rabbit. II. Studies on influencing respiration with exogenic hyperthermia]

Rectal temperature, respiratory rate, arterial and venous pH and arterial and venous pCO2 were recorded at intervals of 15-30 minutes in female broiler rabbits exposed an environmental temperature of 35 degrees C, until they died. Respiratory rate and blood pH rose, and pCO2 fell, until a rectal temperature of 42 degrees C was reached. Upon further increase in rectal temperature the respiratory rate and pH began to fall, while pCO2 began to rise. The rabbits died when rectal temperature reached 43 degrees C. Features of respiratory function peculiar to the rabbit were discussed.     

A comparison of auricular, rectal and pulmonary artery thermometry in dogs with anesthesia-induced hypothermia

Objective: To determine if a correlation exists among auricular, rectal and pulmonary artery (PA) temperatures in hypothermic dogs. Design: Prospective study. Setting: Angiography suite at a college of veterinary medicine. Animals: Sexually intact female research hounds (13.9–25.4 kg; n=8). Measurements and main results: Dogs were anesthetized for instrumentation with a percutaneously placed, thermistor‐tipped, PA catheter. Anesthesia was maintained until the core body temperature decreased to 36.6°C (97.8°F). Anesthesia was discontinued, and auricular and rectal temperatures were obtained every 15 minutes until the PA temperature reached 38.3°C (100.9°F). A strong correlation was noted among the 3 methods of temperature measurement (P<0.001; R≥0.846). No statistical difference was detected among measurement methods at baseline, the minimum temperature attained, nor the median temperature attained. However, at the maximum temperature attained, auricular measurements (37.7±0.4°C or 99.8±0.7°F) were lower than either the rectal (38.3±0.3°C or 100.9±0.5°F) or PA (38.3±0.3°C or 100.9±0.5°F) temperature measurements (P=0.001). Conclusion: There is a strong correlation among rectal, auricular and PA temperatures. Auricular temperature may be used to monitor core body temperature during postoperative rewarming; however, it might be slightly lower than core temperature as normothermia is reached.     

The effects of spontaneous and mechanical ventilation on central cardiovascular function and peripheral perfusion during isoflurane anaesthesia in horses

OBJECTIVE: To compare the effects of spontaneous breathing and mechanical ventilation on haemodynamic variables, including muscle and skin perfusion measured with laser Doppler flowmetery, in horses anaesthetized with isoflurane. STUDY DESIGN: Prospective controlled study. ANIMALS: Ten warm-blood trotter horses (five males, five females). Mean mass was 492 kg (range 420-584 kg) and mean age was 5 years (range 4-8 years). MATERIALS AND METHODS: After pre-anaesthetic medication with detomidine (10 microg kg(-1)) anaesthesia was induced with intravenous (IV) guaifenesin and thiopental (4-5 mg kg(-1) IV) and maintained using isoflurane in oxygen. The horses were positioned in dorsal recumbency. In five animals breathing was initially spontaneous (SB) while the lungs of the other five were ventilated mechanically using intermittent positive pressure ventilation (IPPV). Total anaesthesia time was 4 hours with the ventilatory mode changed after 2 hours. During anaesthesia, heart rate (HR) cardiac output (Qt) stroke volume (SV) systemic arterial blood pressures (sAP), and pulmonary arterial pressure (pAP) were recorded. Peripheral perfusion was measured in the semimembranosus and gluteal muscles and on the tail skin using laser Doppler flowmetry. Arterial (a) and mixed venous (v) blood gases, pH, haemoglobin concentration [Hb], haematocrit (Hct), plasma lactate concentration and muscle temperature were measured. Oxygen content, venous admixture (s/Qt) oxygen delivery (DO(2)) and oxygen consumption (VO(2)) were calculated. RESULTS: During mechanical ventilation, HR, sAP, pAP, Qt, SV, Qs/Qt and PaCO(2) were lower and PaO(2) was higher compared with spontaneous breathing. There were no differences between the modes of ventilation in the level of perfusion, DO(2), VO(2), [Hb], (Hct), or plasma lactate concentration. After the change from IPPV to SB, left semimembranosus muscle and skin perfusion improved, while muscle perfusion tended to decrease when SB was changed to IPPV. Low-frequency flow motion was seen twice as frequently during IPPV compared with SB. CONCLUSIONS: Mechanical ventilation impaired cardiovascular function compared with SB in horses during isoflurane anaesthesia. Muscle and skin perfusion changes occurred with ventilation, although further studies are needed to elucidate the underlying mechanisms.     

Postanesthetic hyperthermia in cats: a retrospective comparison between hydromorphone and buprenorphine

OBJECTIVE: To determine the prevalence of postanesthetic hyperthermia [rectal temperature >40 degrees C (104 degrees F)] in a clinical population of cats. STUDY DESIGN: Retrospective study. ANIMAL POPULATION: One hundred and twenty-five cats with an age range of 2 months to 16.1 years, and weighing 3.9 +/- 1.5 kg. MATERIALS AND METHODS: Data were obtained from the medical records of 125 cats that underwent general anesthesia. Information on perioperative rectal temperatures, breed, sex, weight, surgical procedure, anesthetic time, surgery time, anesthetic and analgesic drugs were retrieved. STATISTICAL ANALYSES: Five groups of cats were compared; group 1 (n = 15) received acepromazine and no opioids; group 2 (n = 17) received acepromazine and buprenorphine; group 3 (n = 19) received acepromazine, buprenorphine and ketoprofen; group 4 (n = 45) received acepromazine and hydromorphone and group 5 (n = 29) received acepromazine, hydromorphone and ketoprofen. Data conformed to a split-plot repeated measures analysis of variance and was analyzed using SAS PROC MIXED. Post hoc tests were by means of Bonferroni t-test; < or = 0.05 was considered significant. RESULTS: Rectal temperature was significantly decreased in all groups at the end of anesthesia. Rectal temperature was significantly elevated at 1, 1.5, 2, 3, 4 and 5 hours after the end of anesthesia in group 4, and at 2, 3 and 4 hours in group 5. Sixty-four percent of cats in group 4 and 69% in group 5 had rectal temperatures >40 degrees C (104 degrees F) at one or more times in the postanesthetic period. The highest temperature recorded was 42.5 degrees C (108.5 degrees F) in one cat in group 4. Mean rectal temperature did not exceed the preoperative temperature at any time during the postanesthetic period in group 1, 2 and 3 animals. CONCLUSIONS: This study indicates an association between hyperthermia and perioperative administration of hydromorphone in cats. CLINICAL RELEVANCE: When hydromorphone is used in cats their body temperature should be closely monitored.     

Effects of treadmill exercise on sweating in three breeds of goats

OBJECTIVE: To compare the sweating responses of three breeds of goats to exercise at 30 degrees C. DESIGN: Factorial experiment with two goats of each of three breeds exercised for 60 min at 3 km/h and 30 degrees C on 6 days. PROCEDURE: Two mature females of the Anglo-Nubian, Saanen and Toggenburg breeds were used. Rectal temperature, respiration rate and sweating rate at three sites were recorded every 20 min during six replicates of exercise at 48 h intervals on a treadmill. RESULTS: Respiration rate varied with time and breed (P < 0.01) and increased from 20 +/- 2 breaths/min to 135, 195 and 260/min after 60 min exercise in Anglo-Nubian, Saanen and Tottenburg goats, respectively. Bread differences in rectal temperature were small but significant (P < 0.001), and mean values increased from 38.9 degrees C before exercise to 39.7 degrees C after 1 h exercise. The breed x sites interaction for sweating was significant (P < 0.01). On the rump breed differences in sweating rate were not significant. On the loin, Toggenburg goats started to sweat most rapidly and reached maximal values of 80.2 +/- 10.6 g/m2/h after 20 min and then decreased to 70.0 +/- 4.3 g/m2/h at 60 min. Sweating rate on the ear was highest in Toggenburg goats, followed by those of Saanen and Anglo-Nubian goats (P < 0.05), but the differences were small (7 g/m2/h); peak values of 67.3 to 76.1 g/m2/h were recorded after 20 min. CONCLUSION: Respiration and sweating rates increased significantly during exercise in all three breeds of goats, but breed differences were marked only for respiration rate. The goats sweated more on the rump than on the loin on ear, with peak values after 40 min of exercise.     

Dobutamine-induced augmentation of cardiac output does not enhance respiratory gas exchange in anesthetized recumbent healthy horses

The influence of pharmacologic enhancement of cardiac output on the alveolar-to-arterial oxygen tension (difference (P[A-a]O2), physiologic right-to-left shunt fraction (Qs/Qt), and physiologic dead space-to-tidal volume ratio (VD/VT) ws studied in halothane-anesthetized horses in left lateral, right lateral, and dorsal recumbencies. Adult horses were anesthetized, using xylazine (2.2 mg/kg, IM), guaifenesin (50 mg/kg, IV), thiamylal (4.4 mg/kg, IV), and halothane (1.5% to 2% inspired) in 100% O2. Mechanical ventilation was controlled to maintain arterial eucapnia (PaCO2) 35 to 45 mm of Hg) for a period lasting at least 1 hour. Dobutamine was administered at dosages of 1, 3, and 5 micrograms/kg/min, IV, on a randomized basis. The P(A-a)O2, Qs/Qt, and VD/VT were calculated during equilibration and after each dobutamine infusion was given. The P(A-a)O2 and Qs/Qt were significantly (P less than 0.05) greater and VD/VT tended to be greater in horses in dorsal recumbency, compared with those values in horses in left lateral or right lateral recumbency. Cardiac output was similar in all horses, regardless of body position (recumbency). The qualitative relationship between horses in the 3 recumbent positions were not altered by dobutamine. Cardiac output was significantly (P less than 0.05) increased by 3 or 5 micrograms of dobutamine/kg/min in all horses, whereas P(A-a)O2, Qs/Qt, and VD/VT were not significantly altered by dobutamine. The results of the present study failed to substantiate our clinical observations of decreased P(A-a)O2 and Qs/Qt in anesthetized compromised horses given dobutamine.     

Post-anesthetic hyperthermia in cats

OBJECTIVE: To assess whether administration of hydromorphone and, or ketamine are associated with post-anesthetic hyperthermia in cats undergoing routine surgery. STUDY DESIGN: Prospective clinical study. ANIMALS: Forty healthy, adult cats undergoing ovariohysterectomy (OVH), castration, or declaw surgery. MATERIALS AND METHODS: Each cat was assigned randomly to one of four groups (n = 10). For pre-anesthetic medication, all cats received subcutaneous (SC) glycopyrrolate (0.01 mg kg(-1)) and acepromazine (0.02 mg kg(-1)) and either hydromorphone (0.1 mg kg(-1) SC) or medetomidine (7.5 microg kg(-1) SC). Anesthesia was induced with either diazepam (0.1 mg kg(-1)) and ketamine (5 mg kg(-1)) or propofol (6 mg kg(-1) injected to effect). Group 1 (HDK) received hydromorphone and diazepam-ketamine. Group 2 (HP) received hydromorphone and propofol. Group 3 (MDK) received medetomidine and diazepam-ketamine. Group 4 (MP) received medetomidine and propofol. Rectal temperature was measured before drugs were given, at tracheal extubation and at hourly intervals for 5 hours thereafter. RESULTS: During the 5 hours after anesthesia and surgery, at least one cat in every group had a rectal temperature >39.2 degrees C (102.5 degrees F). The percentage of observations for which a cat's temperature exceeded its pre-anesthetic temperature in groups HDK, HP, MDK, and MP were 86%, 80%, 25%, and 34%, respectively. Maximum temperatures in groups HDK, HP, MDK, and MP were 41.6 degrees C (107.0 degrees F), 40.3 degrees C (104.2 degrees F), 39.2 degrees C (102.6 degrees F), and 40.1 degrees C (104.1 degrees F), respectively. By 5 hours after tracheal extubation there were no differences in temperature between the treatment groups. CONCLUSION: For up to 5 hours following anesthesia and surgery, cats might have body temperatures that exceed their pre-anesthesia body temperatures. The use of hydromorphone is associated with post-anesthetic hyperthermia. However, hyperthermia may occur when other drugs are used. CLINICAL RELEVANCE: Cats given hydromorphone should be closely monitored for hyperthermia following anesthesia and surgery.     

Reassessment of the toxicity of Hypericum perforatum (St John's wort) for cattle

OBJECTIVE: To investigate the clinical effect of administering sufficient Hypericum perforatum to cattle to deliver quadruple the reported oral toxic dose. ANIMALS: Thirty-six yearling Hereford (n = 18) and Angus (n = 18) steers. DESIGN: A series of six experiments was conducted, each using 12 animals in a 2 x 2 factorial design, with two breeds of cattle (Hereford, Angus) and two dose levels of hypericin, 1.5 mg/kg (treated group) and 0 mg/kg (control group). Each set of 12 steers was used in duplicate experiments, with all animals alternated between treated and control groups. PROCEDURES: Treated groups received finely milled H. perforatum administered orally in gelatin capsules to provide 1.5 mg hypericin/kg body weight. All cattle were then exposed to direct sunlight for 5 h per day for 5 successive days. Rectal temperatures were measured immediately before and at the end of each sunlight exposure session. Rectal temperature above 40 degrees C, together with some other clinical sign of hypericin poisoning, was considered indicative of intoxication. RESULTS: No animals developed a rectal temperature above 40 degrees C or other clinical signs of hypericin poisoning. CONCLUSIONS: While the reported bovine oral toxic dose of 3 g dried plant/kg body weight, for flowering stage, presumed narrow leaved biotype, H. perforatum, is probably correct, the corresponding dose for hypericin of 0.37 mg/kg is incorrect. Based on its known concentration in this plant the toxic dose of hypericin for partially pigmented Hereford-cross cattle is estimated at about 10.5 mg/kg body weight and more than this for fully pigmented cattle. This would imply that cattle of the former type should be about three and a half times better protected against H. perforatum toxicity than are unpigmented, wool protected, Merino sheep. Cattle, particularly if fully pigmented, may have a role in grazing management to control H. perforatum.     

Comparison of temperature readings from a percutaneous thermal sensing microchip with temperature readings from a digital rectal thermometer in equids

OBJECTIVE: To compare temperature readings from an implantable percutaneous thermal sensing microchip with temperature readings from a digital rectal thermometer, to identify factors that affect microchip readings, and to estimate the sensitivity and specificity of the microchip for fever detection. DESIGN: Prospective study. ANIMALS: 52 Welsh pony foals that were 6 to 10 months old and 30 Quarter Horses that were 2 years old. PROCEDURES: Data were collected in summer, winter, and fall in groups 1 (n = 23 ponies), 2 (29 ponies), and 3 (30 Quarter Horses), respectively. Temperature readings from a digital rectal thermometer and a percutaneous thermal sensing microchip as well as ambient temperature were recorded daily for 17, 23, and 19 days in groups 1 through 3, respectively. Effects of ambient temperature and rectal temperature on thermal sensor readings were estimated. Sensitivity and specificity of the thermal sensor for detection of fever (rectal temperature, >or= 38.9 degrees C [102 degrees F]) were estimated separately for data collection at ambient temperatures 15.6 degrees C. RESULTS: Mean ambient temperatures were 29.0 degrees C (84.2 degrees F), -2.7 degrees C (27.1 degrees F), and 10.4 degrees C (50.8 degrees F) for groups 1 through 3, respectively. Thermal sensor readings varied with ambient temperature and rectal temperature. Rectal temperatures ranged from 36.2 degrees to 41.7 degrees C (97.2 degrees to 107 degrees F), whereas thermal sensor temperature readings ranged from 23.9 degrees (75 degrees F) to 42.2 degrees C (75 degrees to 108 degrees F). Sensitivity for fever detection was 87.4%, 53.3%, and 58.3% in groups 1 to 3, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The thermal sensor appeared to have potential use for initial screening of body temperature in equids at ambient temperatures > 15.6 degrees C.     

Effects of increasing temperatures on physiological changes in pigs at different relative humidities

The effects of relative humidity (RH) and high ambient temperature (T) on physiological responses and animal performance were studied using 12 groups (10 gilts per group) in pens inside respiration chambers. The microclimate in the chamber was programmed so that T remained constant within a day. Each day, the T was increased by 2 degrees C from low (16 degrees C) to high (32 degrees C). Relative humidity was kept constant at 50, 65, or 80%. The pigs' average initial BW was 61.7 kg (58.0 to 65.5 kg), and their average ending BW was 70.2 kg (65.9 to 74.7 kg). Respiration rate (RR), evaporative water (EW), rectal temperature (RT), skin temperature (ST), voluntary feed intake (VFI), water-to-feed ratio (rW:F), heat production (HP), and ADG were analyzed. The animals had free access to feed and water. We determined the T above which certain animal variables started to change: the so-called inflection point temperature (IPt) or "upper critical temperature." The first indicator of reaction, RR, was in the range from 21.3 to 23.4 degrees C. Rectal temperature was a delayed indicator of heat stress tolerance, with IPt values ranging from 24.6 to 27.1 degrees C. For both these indicators the IPt was least at 80% RH (P < 0.05). Heat production and VFI were decreased above IPt of 22.9 and 25.5 degrees C, respectively (P < 0.001). For each degree Celsius above IPt, the VFI was decreased by 81, 99, and 106 g/(pig.d) in treatments 50, 65, and 80% RH, respectively. The ADG was greatest at 50% RH (P < 0.05). Ambient temperature strongly affects the pigs' physiological changes and performance, whereas RH has a relatively minor effect on heat stress in growing pigs; however, the combination of high T and high RH lowered the ADG in pigs. The upper critical temperature can be considered to be the IPt above which VFI decreased and RT then increased. Temperatures of the magnitude of both these IPt are regularly measured in commercial pig houses. We conclude that the upper critical temperatures for 60-kg, group-housed pigs fed ad libitum are between 21.3 and 22.4 degrees C for RR, between 22.9 and 25.5 degrees C for HP and VFI, and between 24.6 and 27.1 degrees C for RT. It is clear that different physiological and productive measurements of group-housed, growing-finishing pigs have different critical temperatures.     

High rectal temperature indicates an increased risk of unexpected recovery in anaesthetized badgers

OBJECTIVE: To identify factors associated with sudden early recovery (SER) from anaesthesia in badgers (Meles meles). STUDY DESIGN: Experimental trial. ANIMALS: Ninety-three adult wild badgers. METHODS: Animals were randomly assigned to receive one of four anaesthetics based on medetomidine (M) ketamine (K) and butorphanol (B) combined in different ratios: (i) MKB 20:40:80 microg kg(-1); (ii) MKB 20:40:60 microg kg(-1); (iii) MKB 20:60:40 microg kg(-1); and (iv) ketamine alone 0.2 mg kg(-1). For each animal, induction time was measured and physiological variables (heart rate, respiratory rate and rectal temperature) were recorded at 5-minute intervals during anaesthesia. Cases of SER were recorded and binary logistic regression applied to identify predictive factors. RESULTS: Fourteen animals (15%) exhibited SER. Rectal temperature was the only variable that was a significant predictor of SER. Animals showing SER had significantly higher rectal temperatures which, in contrast to other cases, did not fall during the first 10 minutes of anaesthesia, which was when most SERs occurred. CONCLUSION AND CLINICAL RELEVANCE: We recommend that (i) rectal temperature is closely monitored during wild badger anaesthesia and (ii) that animals with higher than expected temperatures are treated with additional caution.     

Effects of slow infusion of a low dosage of endotoxin on systemic haemodynamics in conscious horses

The effects of intravenous (iv) infusion of endotoxin for 60 mins at a cumulative dosage of 0.03 micrograms/kg bodyweight on systemic arterial, right atrial and pulmonary arterial pressures, heart rate, cardiac output, and derived pulmonary vascular resistance and total peripheral vascular resistance were compared to the effects of iv infusion of saline solution in four healthy horses. Heart rate was increased significantly after endotoxin infusion, although diastolic arterial pressure, systolic arterial pressure, electronically averaged arterial pressure, cardiac output, total peripheral resistance, and right atrial pressure did not change significantly. Average pulmonary arterial pressure was increased significantly by endotoxin infusion. This was accompanied by a trend toward increased diastolic pulmonary arterial pressure (P = 0.1), systolic pulmonary arterial pressure (P = 0.08) and pulmonary vascular resistance (P = 0.07). These results suggest that low dosages of endotoxin produce pulmonary hypertension without causing hypotensive, hypodynamic shock.     

Use of lithium dilution and pulse contour analysis cardiac output determination in anaesthetized horses: a clinical evaluation

OBJECTIVE: To assess the suitability of a human algorithm for calculation of continuous cardiac output from the arterial pulse waveform, in anaesthetized horses. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty-four clinical cases undergoing anaesthesia for various conditions. MATERIALS AND METHODS: Cardiac output (Qt), measured by lithium dilution (QtLiDCO), was compared with a preceding, calibrated Qt measured from the pulse waveform (QtPulse). These comparisons were repeated every 20-30 minutes. Positive inotropes or vasopressors were administered when clinically indicated. Cardiac indices from 30.7 to 114.9 mL kg(-1) minute(-1) were recorded. Unusually shaped QtLiDCO curves were rejected and the measurement was repeated immediately. RESULTS: Eighty-nine comparisons were made between QtLiDCO and QtPulse. The bias between the mean (+/-SD) of the two methods (QtLiDCO - QtPulse) was -0.07 L minute(-1)(+/-3.08) (0.24 +/- 6.48 mL kg(-1) minute(-1)). The limits of agreement were -12.72 and 13.2 mL kg(-1) minute(-1) (Bland & Altman 1986; Mantha et al. 2000). Linear regression analysis demonstrated a correlation coefficient (r2) of 0.89. Cardiac output in individual patients varied from 49.1 to 183% of the initial measurement at the time of calibration. Linear regression of log-transformed Qt variation for each method found a mean difference of 9% with limits of agreement of -4.1 to 22.1%. CONCLUSIONS AND CLINICAL RELEVANCE: This method of pulse contour analysis is a relatively noninvasive and reliable way of monitoring continuous Qt in the horse under anaesthesia. The ability to easily monitor Qt might decrease morbidity and mortality in the anaesthetized horse.     

高温环境下湖羊直肠温度和血液生化指标的监测

本研究以南方特色绵羊品种湖羊为研究对象，在夏季高温环境下，连续监测10 d湖羊直肠温度变化，测定血常规指标，并比较不同年龄、不同性别的湖羊在高温环境下血常规指标的差异；以湖羊高温环境下直肠温度的变化为基础，结合血常规指标，在湖羊群体内鉴别高温应激敏感和高温应激抗性湖羊个体。结果显示，湖羊最高直肠温度出现在环境温度最高的时段（11：00~15：00），最低温度一般出现在03：00左右，且以24 h为周期循环；平均最高直肠温度和最低直肠温度差在湖羊个体间差异显著（P<0.05）；高温暴露后湖羊群体淋巴细胞（LYM）、红细胞（RBC）、血红蛋白（HGB）数量及平均血红蛋白浓度（MCHC）均超出了绵羊正常参考值，且在不同性别和年龄上有一定的差异：母羊嗜碱性细胞、红细胞、血红蛋白、红细胞压积均有高于公羊的趋势，但差异不显著（P>0.05）；1周岁湖羊淋巴细胞（P>0.05）、嗜碱性细胞计数（P<0.01）及百分比（P<0.05）均高于半岁湖羊；依据温度变化结合血常规指标变化在湖羊群体中鉴别了高温应激敏感和抗性的湖羊个体，在测试的母羊群体中高温应激敏感湖羊占35.3%，高温应激抗性湖羊占26.5%。肌酸激酶（CK）含量在高温应激敏感和抗性湖羊个体间差异显著（P<0.05）。综合以上结果，高温环境下湖羊不同个体间直肠温度变化差异显著；从血常规指标来看，高温应激对母羊和1岁湖羊的影响比较大。试验结果为深入研究夏季高温应激对湖羊的影响及抗高温应激差异的分子机制提供了一定的依据。     

Effects of environmental temperature and ammoniation on utilization of straw by sheep

Eighteen sheep were used to compare diets based on ammoniated wheat straw (AWS) or untreated wheat straw (WS) at three thermal environments: hot (HE, 36 degrees C, 70% relative humidity (RH], thermoneutral (TNE, 24 degrees C, 70% RH) and cold (CE, 4 degrees C, 70% RH). Six sheep were housed in each environment for at least 21 d prior to the trial. Two periods of 28 d were used in a crossover design. Within each period, digestibility was measured both under ad libitum intake (collections on d 16 to 20) and at restricted intake (collections on d 24 to 28). Diets consisted of 59% straw, 20% alfalfa hay and 21% concentrate. Urea was added to the untreated straw diet (.75%) to compensate partially for the N present in the AWS. Rectal temperature and respiration rates indicated that sheep in the HE were heat-stressed. Sheep housed in the CE had lower rectal temperatures and respiration rates than sheep in the TNE, but they did not shiver or show other visible signs of cold stress. Voluntary DM intake increased from 604 to 806 g/d, and ad libitum DM digestibility increased from 55.5 to 58.2% when AWS was fed. At restricted intake, ammoniation increased diet digestibility from 58.8 to 61.4%. Voluntary intake was lower in the HE (588 g/d) compared to 763 g/d in the TNE and 764 g/d in the CE. Digestibility of DM at ad libitum intake was lower in the HE (54.6%) than in the TNE (57.5%) or CE (58.6%); respective results at restricted intake were 58.5, 61.0 and 60.7%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of electroacupuncture and butorphanol on respiratory and cardiovascular effects and rectal pain threshold after controlled rectal distention in mares

OBJECTIVE: To compare effects of electroacupuncture and butorphanol on hemodynamic and respiratory variables and rectal analgesia in mares after controlled rectal distention. ANIMALS: 8 healthy mares. PROCEDURE: Each horse received saline (0.9% NaCl) solution (0.01 mL/kg, IV; control treatment), butorphanol tartrate (0.1 mg/kg, IV), or 2 hours of electroacupuncture (EA) at acupoints Bladder 21, 25, and 27 on both sides of the vertebral column, Bai hui, and Stomach 36 (right side only). Order of treatments in each mare was randomized. At least 7 days elapsed between treatments. A balloon was inserted in the rectum of each mare, and controlled distention of the balloon (pressures of < or = 220 mm Hg) was used to measure nociceptive rectal pain threshold. Rectal temperature and cardiovascular and respiratory variables were measured before (baseline) and 5,15, 30, 60, 90, and 120 minutes after onset of each treatment. RESULTS: Butorphanol produced greater increases in rectal pain threshold, compared with EA (mean +/- SD, 214 +/- 24 vs 174 +/- 35 mm Hg of balloon pressure). Electroacupuncture produced minimal cardiovascular and respiratory changes. Although clinically not important, butorphanol produced moderate significant increases in heart and respiratory rates, arterial blood pressure, and rectal temperature and decreases in arterial oxygen tension. Arterial pH, carbon dioxide tension, bicarbonate concentrations, base excess, Hct, and concentration of total solids were not significantly different from baseline values after EA, butorphanol, and control treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Electroacupuncture and butorphanol (0.1 mg/kg, IV) may provide useful rectal analgesia in horses.     

Effect of consuming fungus-infected and fungus-free tall fescue and ergotamine tartrate on selected physiological variables of cattle in environmentally controlled conditions.

Two experiments were conducted to determine the physiological responses of consuming a fungus-free (FF) or fungus-infected (INF) tall fescue diet (Exp. 1) or the FF diet plus ergotamine tartrate at 30 ppm (FF/ET, Exp. 2) in a thermoneutral (21 degrees C) or heat-stressed environment (32 degrees C, dry bulb; 10 degrees C dew point). Treatment periods lasted 28 d after a 10-d adaptation period. Experiment 1 was replicated three times, and Exp. 2 was replicated twice, with eight Holstein steers in each replicate (mean BW = 185 kg). Feed intake (FI), rectal temperature (RT), and respiration rate (RR) were recorded daily, and heart rate (HR) and infrared temperatures at the ear canal (ECT), ear tip (ETT), pastern (PT), coronary band (CBT), and tail tip (TTT) were recorded weekly. Consumption of INF and FF/ET compared with FF diets decreased (P less than .10) FI, HR, ECT, PT, CBT, and TTT and elevated (P less than .10) RT and RR by 2.8, 2.77 kg/d; 17, 23 beats/min; .8, 1.1 degrees C; .9, 1.1 degrees C; .8, .9 degrees C; 1.1, 2.6 degrees C; .3, .5 degrees C; and 8, 8 breaths/min; respectively. Ear-tip temperature was reduced (P less than .10) 1.6 degrees C by consumption of INF but not by consumption of FF/ET. Reduction of peripheral temperatures is indicative of reduced blood flow to peripheral areas as a result of vasoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiopulmonary effects of dexmedetomidine in goats and sheep anaesthetised with sevoflurane

In sheep, alpha(2)-agonists can induce severe hypoxaemia. In goats, reports on changes in oxygenation are inconsistent. The aim of this study was to compare the cardiopulmonary effects of dexmedetomidine in six goats and four sheep anaesthetised with sevoflurane and maintained at approximately 1 minimal alveolar concentration. The animals were ventilated mechanically and held in an upright position to minimise the influence of positioning on pulmonary function. After baseline cardiopulmonary measures, 2 microg/kg dexmedetomidine was injected intravenously over one minute, and measurements were made for 120 minutes. In both species, respiratory resistance, alveolar dead space and shunt fraction increased and thoracic compliance decreased significantly; arterial, pulmonary arterial, pulmonary capillary wedge and central venous pressures increased and heart rate and cardiac output decreased significantly. Arterial oxygen tension decreased significantly, with no significant difference between the goats and sheep. Wide interindividual differences were observed in both the goats (mean [sd] 144 [149.1] mmHg, range 54.8 to 443.7 mmHg) and sheep (mean [sd] 129.8 [132.1] mmHg, range 33.7 to 352.8 mmHg), but the cardiovascular and respiratory changes were similar in the two species.     

Cardiovascular and haemodynamic effects of intramuscular doses of xylazine in conscious sheep

OBJECTIVE: To determine if a commonly used analgesic dose of xylazine has detrimental cardiovascular or haemodynamic effects in sheep. DESIGN: A physiological study following intramuscular administration of xylazine. PROCEDURE: Xylazine (50 micrograms/kg) was injected intramuscularly into six healthy Merino ewes. For 60 min heart rate, mean arterial blood pressure and cardiac output were recorded; arterial blood samples for the measurement of blood gas tensions were also collected. RESULTS: There were no significant changes in heart rate, mean arterial blood pressure, cardiac output or arterial carbon dioxide tension. A slight degree of arterial hypoxaemia was noted with a 10% reduction in arterial oxygen tension values at 30 min. CONCLUSION: The minimal changes to cardiovascular and respiratory values in this study verify the safety of previously suggested analgesic dosing regimens for sheep. Previously reported hypoxaemic effects in sheep as a result of intravenous xylazine administration appear to be reduced as a result of intramuscular administration.