Physiological,pharmacokinetic and liver metabolism comparisons between 3-, 6-, 12- and 18-month-old male Sprague Dawley rats under ketamine-xylazine anesthesia

The main objective of this study was to compare the physiological changes (withdrawal and corneal reflexes, respiratory and cardiac frequency, blood oxygen saturation, and rectal temperature) following intraperitoneal administration of ketamine (80 mg/kg) and xylazine (10 mg/kg) to 3-, 6-, 12- and 18-month-old male Sprague Dawley rats (n=6/age group). Plasma pharmacokinetics, liver metabolism, and blood biochemistry were examined for a limited number of animals to better explain anesthetic drug effects. Selected organs were collected for histopathology. The results for the withdrawal and corneal reflexes suggest a shorter duration and decreased depth of anesthesia with aging. Significant cardiac and respiratory depression, as well as decreased blood oxygen saturation, occurred in all age groups however, cardiac frequency was the most affected parameter with aging, since the 6-, 12-, and 18-month-old animals did not recuperate to normal values during recovery from anesthesia. Pharmacokinetic parameters (T_1/2 and AUC) increased and drug clearance decreased with aging, which strongly suggests that drug exposure is associated with the physiological results. The findings for liver S9 fractions of 18-month-old rats compared with the other age groups suggest that following a normal ketamine anesthetic dose (80 mg/kg), drug metabolism is impaired, leading to a significant increase of drug exposure. In conclusion, age and related factors have a substantial effect on ketamine and xylazine availability, which is reflected by significant changes in pharmacokinetics and liver metabolism of these drugs, and this translates into shorter and less effective anesthesia with increasing age.     

Arterial blood gas tensions and acid-base status of Wistar rats during thiopental and halothane anesthesia.

Arterial blood gas tensions and acid-base status of spontaneously-breathing, unanesthetized Wister rats were compared with values obtained during 4 hr of thiopental and 6 hr of halothane (1%) anesthesia. During thiopental anesthesia, marked respiratory depression occurred (PaCO-2:57.0 plus or minus 10.0 MM Hg, PaO-2:70.4 plus or minus 11.2 MM Hg). Thirty-six percent of the rats died. During inhalation of room air and 1% halothane, PaO-2 decreased also, whereas PaO-2 did not change. Twenty-seven percent of the original number of rats died. Lowered arterial oxygen tension may have caused death; no rats died during inhalation of oxygen and 1% halothane. This technic insured sufficient analgesia for surgical procedures without marked alterations of the acid base status and is recommended for long-term anesthesia of small laboratory animals like rats.     

Respiratory, cardiovascular, and metabolic adjustments to hypoxemia during sleep in piglets

The influence of sleep on ventilation, metabolic rate, cardiovascular function, and regional distribution of blood flow during hypoxemia (PaO2 of 45-50 mm Hg (1 mm Hg = 133.3 Pa)) was studied in piglets at 6+/-1 and 34+/-5 days (mean+/-SD). Measurement of ventilation and metabolic rate was done in a metabolic chamber, and blood flow was measured using the microsphere technique. A subgroup of animals was instrumented for cardiac output measurement (dye-dilution technique) and continuous monitoring of the hemoglobin saturation in oxygen (SaO2). We found that although sleep did not influence the metabolic and cardiac output response to hypoxemia, it affected the ventilatory response as well as the brain and the respiratory muscle blood flows. During active sleep in the older animals, the ventilatory response to hypoxemia was smaller than in the other two states; marked drops in SaO2 occurred with changes in the breathing pattern; and that state was associated with the highest rate of brain blood flow. As well, age affected the ventilatory and metabolic response, but not the cardiovascular response to hypoxemia. The age-dependent ventilatory changes with hypoxemia (smaller ventilatory response in the young than in the older animals) were related to the different levels of oxygen consumption. In summary, active sleep was responsible for all the sleep-dependent changes in the response to a moderate degree of hypoxemia.     

Aging increases the susceptiblity to methamphetamine-induced dopaminergic neurotoxicity in rats: correlation with peroxynitrite production and hyperthermia

Methamphetamine (METH) produces dopaminergic neurotoxicity by the production of reactive oxygen (ROS) and nitrogen (RNS) species. The role of free radicals has also been implicated in the process of aging. The present study was designed to evaluate whether METH-induced dopaminergic neurotoxicity and hyperthermia is a result of peroxynitrite production and if these effects correlate with age. One-, six- and 12-month-old male rats (n = 8) were administered a single dose of METH (0, 5, 10, 20, and 40 mg/kg, intraperitoneally). The formation of 3-nitrotyrosine (3-NT) as a marker of peroxynitrite production as well as dopamine and its metabolites DOPAC and HVA were measured in the striatum 4-h after METH-administration. Rectal temperature was monitored every 30 min after METH administration until 4 h. At 40 mg/kg METH, a 100% mortality in 12-month-old animals was observed, whereas no deaths occurred in 1- or 6-month-old rats. An age-dependent increase in hyperthermia was observed after METH-administration. A similar pattern of dose-dependent increase in the formation of 3-NT and in the depletion of dopamine and its metabolites with age was observed in the striatum. Furthermore, no effect was observed at 5 mg/kg METH in 1-month-old animals, whereas the effect was significant in 6- and 12-month-old animals. These data suggest that aging increases the susceptibility of the animals toward METH-induced peroxynitrite generation and striatal dopaminergic neurotoxicity.     

Anesthesia of wild red howler monkeys (Alouatta seniculus) with medetomidine/ketamine and reversal by atipamezole

Wild red howler monkeys (Alouatta seniculus) were translocated during the flooding of the forest at a hydroelectric dam site in French Guiana. For a variety of minor clinical procedures, 96 monkeys were anesthetized with various intramuscular injections of combinations of medetomidine and ketamine. The howler population was composed of healthy animals (42 males and 54 females) of various ages. Medetomidine (150 μg/kg) associated with ketamine (4 mg/kg) gave the best results and was used on 63 animals. The injection rapidly resulted in complete immobilization with good to excellent myorelaxation. The induction stage was quiet, with absence of both corneal and pedal withdrawal reflexes in 57 animals after 2.9 ± 1.4 min. Six animals required an additional injection. Rectal temperature and respiratory and heart rates decreased during anesthesia, whereas relative oxyhemoglobin saturation increased. One death occurred during anesthesia. One abortion and one death also occurred the day following anesthesia but were more probably a result of capture stress. Atipamezole given i.m. at a dose of five times the medetomidine dose 38.4 ± 8.0 min after the anesthetic injection led to standing recovery in 7.1 ± 4.5 min. Spontaneous recovery occurred in 17 animals before the atipamezole injection after an average of 30.6 ± 9.6 min. Total recovery time was shorter in young animals. Medetomidine/ketamine induced good myorelaxation and provided considerably shortened immobilization duration, which are two notable advantages for field studies. We recommend this association for short procedures including minor surgery in red howler monkeys. Am. J. Primatol. 45:399–410, 1998. © 1998 Wiley-Liss, Inc.     

Increased incidence of isoproterenol-induced ventricular fibrillation in aging rats

Prolonged beta-adrenergic stimulation obtained by subcutaneous injection of isoproterenol in unanesthetized, unrestrained rats elicited ventricular fibrillation in approximately 80% of animals at 10-12 months of age. Ventricular fibrillation failed to occur in 1-month-old rats and involved only 12% of rats at 2 months. Senescence appeared not to increase the frequency of ventricular fibrillation since a similar incidence was seen in rats at 10-12 and 19-21 months. In all instances, ventricular fibrillation was preceded by ECG changes consistent with acute subendocardial ischemia. To evaluate whether acute beta-adrenergic stimulation elicits comparable cardiovascular effects in animals of different age, a dose-response curve to intravenous injection of isoproterenol was performed in anesthetized rats. Changes in heart rate, systemic arterial pressure, left ventricular pressure, and dP/dt were not different among animal groups. It was concluded that the arrhythmogenic potential of isoproterenol may not be related to differences in cardiac beta-receptor sensitivity with age as suggested by the comparable changes in the inotropic and chronotropic actions of isoproterenol in the animal groups studied.     

Effect of cadmium sulphate on the metabolism of carbohydrates in organism of rats of different ages

The influence of cadmium sulfate on concentration of glucose, lactate, piruvate, alpha-ketoglutarate, malate, oxaloacetate in blood of 3-, 6- and 18-month-old poisoned rats was established the results of our researches. It was found, that poisoning of rats by cadmium sulfate causes the rise of concentration of glucose, metabolites of citric acid cycle and glycolysis in blood of animals of all age groups explored. The research results prove that in blood of 3-month-old poisoned rats the level of glycolysis and citric acid cycle activation is considerably higher in comparison with that of 6- and 18-month-old animals. As a result, a comparison of age-specific dynamics of changes of carbohydrate metabolism indices in the blood of rats, poisoned by cadmium showed that the organism of 3-month-old rats is more sensitive to toxic influence of cadmium.     

The adrenal medulla and adrenergic innervation of the ventricles of the heart during the postnatal period of ontogenesis of the white rat (histofluorescent study)

The sympathetic innervation of the cardiac ventricles and dynamics of catecholamine contents in the adrenal medulla have been investigated in inbred white rats (1-3-week-old, immature, mature and old animals). During 1-3 weeks of age, development of adrenergic innervation of the heart is observed, in 1.5-month-old rats in approaches that in mature animals. In the old rats the arrangement density and fluorescent intensity of the adrenergic terminals of the cardiac ventricles in comparison to those in the mature animals decreases considerably. Catecholamine contents in the adrenal medulla in 3-week-old rats practically reaches those specific for mature animals. In the old animals the amount of catecholamines in the adrenal medulla decreases by 20%, comparing to those in the mature animals. Thus, maturation of the mediator link of the sympatho-adrenomedullary system is performed in it later than the hormonal one, while processes of old age involution are more intensive.     

Distribution of the kinin-breakdown activity in areas of the rat brain in the dynamics of spontaneous hypertension

Kinin-damaging activity (KDA) has been studied in 8 brain areas of normotensive rats and rats with spontaneous hypertension, aged 3 to 12 months. A significant depression in KDA was revealed in midbrain, striatum, thalamus, and pituitary body of normotensive rats 6 months of age, as compared to 3-month-old animals. A tendency towards KDA increase was noted in the hypothalamus. In 12-month-old normotensive rats KDA level returned to baseline (3 months of age). Comparison of KDA in rats with spontaneous hypertension aged 3 to 12 months has revealed no age-dependent differences and it is, therefore, believed that rats with spontaneous hypertension lack certain mechanisms inducing a considerable decrease of KDA in 6-month-old normotensive rats.     

Effect of graded doses of tri-iodothyronine on ventricular myosin ATPase activity and isomyosin profile in young and old rats.

Ventricular myosin ATPase activity, V1 isomyosin content and serum T3 (tri-iodothyronine) values decrease with age in male Fischer 344 rats. To determine if the age decrement in ATPase activity and V1 isomyosin content are caused by decreased T3 levels or an age-related decrease in V1 isomyosin induction by T3, 3-, 12- and 24-month-old male Fischer 344 rats were given constant T3 infusions by osmotic minipump. Rats at all ages were given 0.75, 5 and 15 micrograms(/100 g per 24 h) doses of T3, whereas 12- and 24-month-old rats were given an additional 0.4 microgram dose. In control rats, T3 levels decreased from 97 +/- 2.7 at 3 months to 75 +/- 4.7 ng/100 ml at 24 months. Likewise, Ca2+-activated myosin ATPase activity decreased from 1.04 +/- 0.05 to 0.68 +/- 0.05 mumol of Pi/min per mg of protein, and the relative proportion of V1 of isomyosin decreased from 90 +/- 4.0 to 26 +/- 2.0%. The lowest (0.4 microgram) T3 dose, which was sufficient to restore T3 levels in 24-month-old animals to 3-month control values, abolished the age decrement in myosin ATPase activity and markedly increased the proportion of V1 isomyosin present in the ventricle. These findings indicate that the senescent ventricle responds readily to small doses of T3 and strongly suggest that the age decrement in serum T3 levels is sufficient to contribute to the age-related decrease in myosin ATPase activity and V1 isomyosin content. Since these parameters correlate with ventricular contractility, the age decrement in T3 levels may also contribute to the decreased ventricular contractility and cardiac output observed in senescent rats.     

Reversible immobilization of free-ranging African lions (Panthera leo) with medetomidine-tiletamine-zolazepam and atipamezole

A combination of medetomidine-tiletamine-zolazepam was used to conduct six immobilizations of free-ranging lions (Panthera leo) in Waza National Park, Cameroon, during 1999 and 2000. Drugs were administered by dart injection at 0.07+/-0.01 (mean+/-SD) mg/kg of medetomidine and 1.8+/-0.5 mg/kg of tiletamine-zolazepam. Chemical immobilization was characterized by smooth inductions (14.1+/-6 min), satisfactory analgesia, and muscle relaxation. One animal was treated for bradypnea. No major alterations of physiologic parameters (heart and respiratory rates, rectal temperature) were seen during immobilization in the other lions. Relative arterial oxygen saturation was measured in two animals and revealed mild hypoxemia. The animals received atipamezole at 0.3+/-0.1 mg/kg intramuscularly for reversal of anesthesia. Recoveries were uneventful. All animals were radiocollared, and no mortalities occurred during an 18-mo follow-up period. Use of medetomidine-tiletamine-zolazepam for anesthesia and reversal of anesthesia with atipamezole appear to be useful for reversible immobilization of free-ranging lions.     

Respiratory Cardiac Arrhythmia in Postnatal Ontogenesis of Rats

Development of the respiratory cardiac arrhythmia and the role of parasympathetic nervous system in its origin have been studied in rats aged from 4–6 days to 6 months of life. In rat pups of the first week of life, small fluctuations of cardiac rhythm were observed with the frequency close to fluctuations of respiratory rhythm. However, at this age they had neither regular character nor clear connection with phases of the respiratory cycle. On the 2–3rd week the amplitude of fluctuations rose and their association with respiration was established; however, unlike the respiratory arrhythmia observed in other animals and human, in rat pups there was deceleration but not acceleration of heart beating. By to the 6-week age the respiratory arrhythmia reached the maximal values, then its amplitude began to decrease. Bilateral transection of the vagus nerves in rat pups did not cause reduction of the respiratory arrhythmia. Thus, in rats the central influences on the heart can be transduced by bypassing the system of vagus nerves.     

Onset and evolution of nephropathy in rats with spontaneous diabetes mellitus

The occurrence of renal diabetic complications was studied in diabetic nonobese IIM/FmeSS (eSS) rats. The results were compared with eumetabolic Wistar rats paired by sex and age. Between 6 and 12 months of age, eSS male rats had higher fructosamine values and glucose intolerance as well as increasing proteinuria and uremia. Enhancement in water, calcium and phosphorus fractional excretion with a concomitant lower sodium excretion, was observed from 12 months of age on. 18- and 21-month-old eSS rats exhibited fasting hyperglycaemia and rising values of fructosamine, glucose intolerance and glycosuria. Simultaneously, a notorious worsening of proteinuria as well as alterations in glomerular filtration were verified. Optic microscopy of 12-month-old eSS rat kidneys showed areas of tubular dilatation with protein cylinders. In 21-month-old eSS animals, kidneys appeared overtly damaged. Increased capsular, glomerular and Henle's thin loop diameters were verified in 12- and 21-month-old eSS rats. Glomeruli showed diffuse hypertrophy of mesangial tissue and thickening of the basement membrane. Areas of markedly atrophic and dilated tubules containing acidophilic proteinaceous material were observed. At age of 21 months, kidneys of eumetabolic Wistar control rats presented foci of interstitial and pielic inflammatory infiltrates.     

Respiratory and cardiovascular effects of thyrotropin-releasing hormone as modified by isoflurane, enflurane, pentobarbital and ketamine

Thyrotropin-releasing hormone (TRH) possesses significant arousing and cardio-respiratory stimulant actions. The effects of a 2 mg/kg i.v. bolus dose of TRH on respiration and systemic hemodynamics were compared in conscious, freely-moving rats and during anesthesia with 4 different anesthetics. Fifty-four male Sprague-Dawley rats weighing 285 +/- 4 g (mean +/- S.E.M.) were divided into 5 groups: conscious, enflurane (2%), isoflurane (1.4%), pentobarbital (8 mg/kg/h i.v.), and ketamine (60 mg/kg/h i.v.). Anesthetized rats were intubated and breathed oxygen or anesthetic/oxygen spontaneously. Aortic blood pressure, heart rate, cardiac output, respiratory rate, arterial blood pH, blood gases, lactate and glucose were measured, and data were collected over a 20 min baseline period and for 130 min post-TRH. TRH increased respiratory rate in all groups; concomitant changes in arterial PCO2 indicated increased minute ventilation in the inhalation agent groups but not in the i.v. anesthetic groups or in the awake group. Significant respiratory depression in the enflurane group was rapidly reversed by TRH. The respiratory stimulant and arousing effects of TRH were smallest with ketamine anesthesia. The hemodynamic responses to TRH were consistent with a pattern of sympathoadrenalmedullary activation and were relatively uniform across groups despite anesthetic-induced alterations in baseline values. TRH or its analogues may prove useful as an analeptic in clinical anesthesia.     

Cardiorespiratory effects of diazepam-ketamine, xylazine-ketamine and thiopentone anesthesia in male Wistar rats--a comparative analysis

Several anesthetics are known to cause respiratory and cardiovascular depression in humans and animals; but, these diverse effects have not been extensively investigated in laboratory rodents. The objective of this study is to choose a suitable anesthetic combination for use in surgical models eg. coronary artery ligation in rats. Male Wistar rats were anesthetized with three different drugs viz. diazepam-ketamine (DK) (2.5 mg/Kg, intraperitoneally (i.p); 50 mg/Kg, i.p), xylazine-ketamine (XK) (5 mg/Kg i.p; 50 mg/Kg i.p) and thiopentone (T) (40 mg/Kg i.p) and the respiratory and cardiovascular functions were assessed after coronary artery ligation. Heart rate (HR), mean arterial pressure (MAP), partial pressure of carbon dioxide (PaCO2), partial pressure of oxygen (PaO2), oxygen saturation percentage (O2 sat (%)), arterial blood pH and rectal body temperature were studied in detail. During the anesthetic regime, HR was lower till 60 min in XK and T ligated group (333 +/- 6; 304 +/- 8 beats/min) and it was near normalcy in the case of DK ligated group (394 +/- 6 beats/min). Significant respiratory depression was particularly reflected in the T ligated group with an increase in PaCO2 at 30 min (40.32 +/- 2.64 mmHg), which decreased to 38.2 +/- 2.23 mmHg at 60 min. Throughout the investigation, DK showed the least overall effects compared to XK and T on respiratory functions. Thus, DK could be considered to be a suitable anesthetic for use in a surgical model such as coronary artery ligation in albino rats.     

Age Related Changes from Youth to Adulthood in Rat Brain Cortex: Nitric Oxide Synthase and Mitochondrial Respiratory Function

Age related changes in brain cortex NO metabolism were investigated in mitochondria and cytosolic extracts from youth to adulthood. Decreases of 19%, 40% and 71% in NO production were observed in mitochondrial fractions from 3, 7, and 14 months old rats, respectively, as compared with 1-month-old rats. Decreased nNOS protein expression in 14 months old rats was also observed in mitochondria as compared with the nNOS protein expression in 1-month-old rats. Low levels of eNOS protein expression close to the detection limits and no iNOS protein expression were significantly detected in mitochondrial fraction for both groups of age. NO production in the cytosolic extracts also showed a marked decreasing tendency, showing higher levels than those observed in mitochondrial fractions for all groups of age. In the cytosolic extracts, however, the levels were stabilized in adult animals from 7 to 14 months. nNOS protein expression showed a similar age-pattern in cytosolic extracts for both groups of age, while the protein expression pattern for eNOS was higher expressed in adult rats (14 months) than in young animals. As well as in mitochondrial extracts iNOS protein expression was not significantly detected in cytosolic extracts at any age. RT-PCR assays indicated increased levels of nNOS mRNA in 1-month-old rats as compared with 14 months old rats, showing a similar pattern to that one observed for protein nNOS expression. A different aged pattern was observed for eNOS mRNA expression, being lower in 1-month-old rats as compared with 14 months old animals. iNOS mRNA was very low expressed in both groups of age, showing a residual iNOS mRNA that was not significantly detected. State 3 respiration rates were 78% and 85% higher when succinate and malate-glutamate were used as substrates, respectively, in 14 months rats as compared with 1-month-old rats. No changes were observed in state 4 respiration rates. These results could indicate 1 that nNOS and eNOS mRNA and protein expression can be age-dependent, and confirmed the nNOS origin for the mitochondrial NOS. During rat growth, the respiratory function seems to be modulated by NO produced by the different NOS enzymes: nNOS, eNOS and mtNOS present in the cytosol and in the mitochondria.     

Transient hypercapnic stress causes exaggerated and prolonged elevation of cardiac and renal interstitial norepinephrine levels in conscious hypertensive rats

The responses of sympathetic nerve activity to transient stress can be exaggerated in salt-sensitive (SS), hypertensive subjects. Cardiac and renal interstitial norepinephrine (iNE) levels during and after transient hypercapnia were investigated in conscious SS rats. Dahl SS and salt-resistant (SR) 6-wk-old rats were fed a high-salt diet, and at 12 wk iNE levels in the heart and kidney were determined using microdialysis with probes inserted in the left ventricular (LV) wall and kidney. A telemetry system determined blood pressure and heart rate (HR) in separate animals. After recovery from the operation, data were collected before, during, and after exposure to normoxic 10% CO(2) for 25 min under unanesthetized conditions. The plasma NE concentrations at baseline did not differ between the two strains. Both cardiac and renal iNE levels were much higher in SS rats than in SR rats at baseline as well as during hypercapnic stress. After stress, the markedly increased iNE levels of SS rats were prolonged in the LV as well as in the kidney. During hypercapnic stress, HR decreased in both SS and SR rats, while sudden increases in HR immediately after the withdrawal from stress were followed by its slower reduction in SS rats compared with SR rats. In conclusion, transient hypercapnic stress causes exaggerated and prolonged elevation of iNE levels in the heart as well as in kidneys of SS animals.     

Effect of age on bone mineral density and the serum concentration of endogenous nitric oxide synthase inhibitors in rats

Results of previous studies have indicated that bone mineral density (BMD) is decreased in aged animals and elderly humans, and that treatment with nitric oxide (NO) donors prevents bone loss. Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase (NOS) inhibitor, can inhibit NO synthesis. In the study reported here, we examined age-related changes in the serum content of ADMA and in BMD in various skeletal regions. The BMD in the lumbar part of the spine, the femur, and the tibia in 12-month-old rats was markedly increased, compared with that in 6-month-old rats, and the BMD in 20-month-old rats was decreased, compared with that in 12-month-old rats. Serum concentration of ADMA in 20-month-old rats was significantly increased, compared with that in 6- or 12-month-old rats. A similar age-related change in the concentration of lipid peroxide also was seen in the three age groups. These results suggest that the increased amount of endogenous ADMA may be associated with an age-related decrease in BMD in rats.     

Evaluation of two combinations of Domitor, Zoletil 100, and Euthatal to obtain long-term nonrecovery anesthesia in Sprague-Dawley rats

We sought to evaluate a new protocol designed to maintain long-term, nonrecovery, surgical anesthesia in Sprague-Dawley rats. In the first phase, two groups of rats were anesthetized with two different dose combinations of Domitor (medetomidine) and Zoletil 100 (tiletamine-zolazepam) to investigate their efficacy in induction of anesthesia. One combination comprised Domitor at 35 microg/kg and Zoletil 100 at 40 mg/kg, whereas the other comprised Domitor at 50 microg/kg and Zoletil 100 at 20 mg/kg. Both combinations effectively induced deep anesthesia and caused no mortality, but the duration of anesthesia differed statistically. In the second phase, we induced anesthesia with both Domitor-Zoletil 100 dose combinations then investigated the possibility of maintaining anesthesia for 5 h by administering Euthatal (pentobarbitone) intra-arterially at 10 mg/kg hourly. Depth of anesthesia, mortality, physiological parameters, blood gas analysis, hematology, clinical chemistry, and postmortem histopathology were recorded. Euthatal provided stable long-term anesthesia with both dose combinations of Domitor-Zoletil 100. Seven of 8 (88%) animals anesthetized with Domitor at 50 microg/kg and Zoletil 100 at 20 mg/kg successfully were maintained under deep anesthesia for 5 h. Higher mortality (36% versus 12%) occurred in group of animals treated with Domitor at 35 microg/kg and Zoletil 100 at 40 mg/kg. This difference may be linked to dose-related respiratory depression, as alterations of arterial gas levels were noted. Our findings suggest that, when long-term nonrecovery anesthesia is required, doses of 50 microg/kg Domitor and 20 mg/kg Zoletil 100 are preferable when given with Euthatal to maintain physiological conditions in animals.