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Relative effects of xylazine-atropine, xylazine-atropine-ketamine, and xylazine-atropine-pentobarbital combinations and time-course effects of the latter two combinations on brain stem auditory-evoked potentials in dogs.

Brain stem auditory-evoked potentials (BAEP) were recorded in 4 dogs to analyze the relationship between acoustic stimulus intensities and peak latencies of each wave, and to investigate the relative effects of xylazine-atropine, xylazine-atropine-ketamine, and xylazine-atropine-pentobarbital combinations and the time-course effects of the latter 2 drug combinations on BAEP. Click stimulations fixed at a stimulus rate of 10/s and a frequency of 4 kHz were delivered at intensities ranging from 10- to 110-dB sound pressure level (SPL) in 10-dB steps for analyzing the relationship between the acoustic stimulus intensities and the peak latencies and at an intensity of 110-dB SPL for investigating the effects of the sedative and anesthetic drug combinations and their time-course effects on BAEP. Waves I to VI were identified with stimulus intensity of greater than or equal to 50-dB SPL. Wave VII was observed in some records, but was excluded from statistical analysis. As stimulus intensity was increased from 50- to 110-dB SPL, the latency decreased for all waves during xylazine-atropine-ketamine anesthesia. There were no statistically significant differences in the peak latencies of each wave in BAEP among xylazine-atropine, xylazine-atropine-ketamine, and xylazine-atropine-pentobarbital combinations 20 minutes after drug administration, except that the latency of wave VI during xylazine-atropine sedation was significantly (P less than 0.01) shorter than that detected during xylazine-atropine-ketamine or xylazine-atropine-pentobarbital anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗

Comparison of anesthetic and cardiorespiratory effects of tiletamine-zolazepam-xylazine and tiletamine-zolazepam-xylazine-butorphanol in ferrets.

Nine ferrests were used in a crossover study to determine the anesthetic effects of intramuscular (i.m.) administration of a low dose of tiletamine-zolazepam (1.5 mg/kg body weight)-xylazine (1.5 mg/kg body weight); a high dose of tiletamine-zolazepam (3 mg/kg body weight)-xylazine (3 mg/kg body weight); and tiletamine-zolazepam (1.5 mg/kg body weight)-xylazine (1.5 mg/kg body weight)-butorphanol (0.2 mg/kg body weight). All ferrets became laterally recumbent within two minutes following the administration of each drug combination. The tiletamine-zolazepam-xylazine-butorphanol combination induced significantly longer (p less than 0.05) durations of tail clamp analgesia (mean +/- standard deviation [SD], 90.0 +/- 17.1 min versus 17.8 +/- 15.8 min and 41.9 +/- 26.3 min) and endotracheal intubation (mean +/- SD, 84.8 +/- 21.7 min versus 5.2 +/- 10.3 min and 26.3 +/- 29.8 min) than the low-dose tiletamine-zolazepam-xylazine and high-dose tiletamine-zolazepam-xylazine combinations, respectively. Heart rates and the times from dorsal recumbency to standing were not significantly different among the three treatment groups. However, systolic blood pressure was significantly lower in the tiletamine-zolazepam-xylazine-butorphanol group. Ventilatory function was more depressed in the tiletamine-zolazepam-xylazine-butorphanol group than in the low-dose tiletamine-zolazepam-xylazine and high-dose tiletamine-zolazepam-xylazine groups. A short period of hypoxia was observed in the tiletamine-zolazepam-xylazine-butorphanol-treated ferrets. Tiletamine-zolazepam-xylazine-butorphanol was found to be the best of the three combinations evaluated in these ferrets. The addition of butorphanol to the low-dose tiletamine-zolazepam-xylazine combination greatly enhanced the duration of analgesia, endotracheal intubation, and dorsal recumbency. However, since hypoxemia occurred during the tiletamine-zolazepam-xylazine-butorphanol anesthesia, oxygen (O2) insufflation is recommended. Doubling the dose of the low-dose tiletamine-zolazepam-xylazine increased the duration of analgesia and endotracheal intubation without prolonging the recovery when compared to the low-dose tiletamine-zolazepam-xylazine group.

Analgesics, Opioid↗

Comparison of xylazine with tiletamine-zolazepam (Telazol) and xylazine-ketamine anesthesia in rabbits.

Although widely used to provide short term anesthesia, ketamine-xylazine does not always produce satisfactory anesthesia. We compared the efficacy of ketamine-xylazine to tiletamine-zolazepam-xylazine for producing surgical anesthesia in rabbits. Four of six rabbits receiving ketamine-xylazine and all of the 12 animals given tiletamine-zolazepam-xylazine were anesthetized successfully. The mean surgical anesthesia time in the ketamine-xylazine group was 35 +/- 6 minutes as compared to the tiletamine-zolazepam-xylazine group, 72 +/- 8 minutes (p less than 0.05). There was no significant difference in the interval between the injection of the different anesthetic mixtures and the loss of either the righting reflex, the jaw reflex or the toe web pinch reflex. Respiratory rates and arterial oxygen partial pressure were higher in the ketamine-xylazine group (p less than 0.05). However, in both groups arterial blood pressure and arterial PO2 were lowered, while arterial PCO2 was elevated. No nephrotoxicity occurred. Tiletamine-zolazepam-xylazine provides effective surgical anesthesia in rabbits and in many cases may be preferable to conventional ketamine-xylazine regimen.

Anesthesia↗

Sedation with xylazine and lumbosacral epidural administration of lidocaine and xylazine for umbilical surgery in calves.

OBJECTIVE: To determine whether anesthesia consisting of sedation induced by intramuscular administration of xylazine hydrochloride and lumbosacral analgesia induced by epidural administration of lidocaine and xylazine is useful for umbilical surgery in neonatal calves. DESIGN: Prospective study. ANIMALS: 6 neonatal male dairy calves. PROCEDURE: Calves were sedated with xylazine (0.1 mg/kg [0.045 mg/lb] of body weight, i.m.), and 5 minutes later a 2% solution of lidocaine (0.18 to 0.24 ml/kg [0.08 to 0.11 ml/lb]) and xylazine (0.05 mg/kg [0.022 mg/lb]) were administered into the lumbosacral epidural space. Calves were positioned in dorsal recumbency, and the umbilical structures were resected. Local infusion of lidocaine, cranial to the umbilicus, was required in 5 of 6 calves to provide adequate analgesia. Xylazine sedation was reversed with tolazoline (1 mg/kg [0.45 mg/lb], i.v.). RESULTS: Calves maintained adequate cardiac output and oxygen delivery throughout the procedure but were hypotensive. Reversal of xylazine-induced sedation with tolazoline caused transient sinus bradycardia and sinus arrest, accompanied by severe systemic arterial hypotension. All calves regained a suckle reflex within 10 minutes and were able to stand within 90 minutes. CLINICAL IMPLICATIONS: Intramuscular administration of xylazine for sedation and epidural administration of lidocaine and xylazine for analgesia failed to provide satisfactory analgesia for umbilical resection without supplemental local infiltration of lidocaine. The anesthetic protocol is most useful when respiratory compromise or cost are concerns and the surgical procedure can be completed in < 1 hour. Caution should be exercised when tolazoline is administered intravenously to reverse xylazine-induced sedation in calves.

Adrenergic alpha-Agonists↗

Cardiac performance in cats after administration of xylazine or xylazine and glycopyrrolate: echocardiographic evaluations.

Cardiac performance was evaluated in 9 healthy cats sedated with xylazine. Each cat was evaluated echocardiographically before and after the administration of xylazine or xylazine and glycopyrrolate. Each cat was echocardiographically evaluated during manual restraint only (control value), after IM administration of 0.55 mg of xylazine/kg of body weight, after IM administration of 2.2 mg of xylazine/kg, and after IM administration of 0.011 mg of glycopyrrolate/kg followed 10 minutes later by IM administration of 2.2 mg of xylazine/kg. Echocardiographic indices of cardiac performance (fractional shortening, left ventricular wall amplitude, aortic amplitude, mitral valve E point septal separation) indicated a significant decrease (P less than 0.05) in the left ventricular function and heart rate after the small (0.55 mg/kg) and large (2.2 mg/kg) dosages of xylazine. With the administration of glycopyrrolate, the bradycardia was minimized, but cardiac performance was not improved. After administration of glycopyrrolate, cardiac performance decreased, but the decrease was not significant when compared with the ventricular performance of the cats after administration of the large dosage of xylazine. Compared with control values, the reduction in left ventricular function values associated with administration of xylazine or xylazine and glycopyrrolate was independent of the heart rate. Therefore, the alpha-2 adrenergic agonist xylazine has a marked depressive effect on cardiac performance in the cat, and premedication with glycopyrrolate may not completely alleviate the undesirable bradycardia, but may actually be detrimental to the cardiovascular system.

Animals↗

Increasing xylazine dose-enhanced anesthetic properties of telazol-xylazine combination in swine.

We evaluated combinations of telazol, ketamine, and xylazine (TKX), telazol and xylazine (TX), telazol, xylazine, and xylazine (T2X), and ketamine and xylazine (KX) for chemical restraint and anesthesia induction in swine. Forty healthy mixed-breed pigs were randomly assigned to the four treatment groups with 10 pigs in each group. For TKX, TX, and T2X combinations, anesthetics were premixed by adding xylazine and ketamine, sterile water and xylazine, or xylazine alone directly into the telazol vial. For KX, anesthetic agents were drawn up separately, then mixed in the same syringe immediately before injection. All anesthetics were given as a single intramuscular injection. All four anesthetic combinations induced a rapid onset of sternal recumbency within 1.55 +/- 0.5 min and lateral recumbency within 2.27 +/- 0.6 min in pigs after intramuscular injection. There was no significant difference among treatments in these regards. The T2X combination induced a significantly longer duration of analgesia than did either TKX, TX, or KX. The T2X combination also induced a significantly longer duration of tolerance for endotracheal intubation and duration of lateral recumbency. Heart and respiratory rates were not significantly different among the four treatment groups. Vomiting was not observed in any of the treated pigs throughout the procedure. Recovery quality and duration from time of drug administration to recovery of pig walking unassisted were similar in three treatment groups but was shorter in KX-treated pigs. We concluded that all four anesthetic combinations were suitable for chemical restraint but that only TKX, TX, and T2X were suitable for anesthesia induction in pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗

Acute reversible cataract induced by xylazine and by ketamine-xylazine anesthesia in rats and mice.

Combined administration of ketamine and xylazine is used increasingly for safe, effective anesthesia of small laboratory animals. We found that rats injected systemically with ketamine and xylazine at doses recommended for effective anesthesia developed acute reversible lens opacities. Mice given the same drug doses were similarly affected. Testing of each drug alone demonstrated that xylazine was the causative agent. The appearance of cataract was associated to varying degree with proptosis, suppression of the blink reflex, corneal surface drying, and mydriasis. All of these ocular effects, including cataract also could be induced locally by topical application of xylazine to one eye, with untreated contralateral eyes showing no drug effects. A possible cause of xylazine-induced transient lens opacification is trans-corneal water loss and alteration of aqueous humor composition due to corneal exposure. Additional action on aqueous humor formation and the lens itself may be due to the alpha-2-adrenoceptor nature of xylazine. Whatever the cause of cataract induction, the occurrence of this phenomenon during ketamine-xylazine anesthesia appears to be associated with marked changes in the physiological state of the eye. Therefore, the side-effects of anesthetic drug combination should be considered prior to its use on animals for studies of ocular physiology.

Acute Disease↗

Cardiorespiratory and metabolic effects of xylazine, detomidine, and a combination of xylazine and acepromazine administered after exercise in horses.

OBJECTIVE: To determine sedative, cardiorespiratory and metabolic effects of xylazine hydrochloride, detomidine hydrochloride, and a combination of xylazine and acepromazine administered i.v. at twice the standard doses in Thoroughbred horses recuperating from a brief period of maximal exercise. ANIMALS: 6 adult Thoroughbreds. PROCEDURE: Horses were preconditioned by exercising them on a treadmill to establish a uniform level of fitness. Each horse ran 4 simulated races, with a minimum of 14 days between races. Simulated races were run at a treadmill speed that caused horses to exercise at 120% of their maximal oxygen consumption. Horses ran until they were fatigued or for a maximum of 2 minutes. One minute after the end of exercise, horses were treated i.v. with xylazine (2.2 mg/kg of body weight), detomidine (0.04 mg/kg), a combination of xylazine (2.2 mg/kg) and acepromazine (0.04 mg/kg), or saline (0.9% NaCl) solution. Treatments were randomized so that each horse received each treatment once, in random order. Cardiopulmonary indices were measured, and samples of arterial and venous blood were collected immediately before and at specific times for 90 minutes after the end of each race. RESULTS: All sedatives produced effective sedation. The cardiopulmonary depression that was induced was qualitatively similar to that induced by administration of these sedatives to resting horses and was not severe. Sedative administration after exercise prolonged the exercise-induced increase in body temperature. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of xylazine, detomidine, or a combination of xylazine-acepromazine at twice the standard doses produced safe and effective sedation in horses that had just undergone a brief, intense bout of exercise.

Acepromazine↗

The effect of xylazine and xylazine followed by insulin on blood glucose and insulin in the dairy cow.

The effect of xylazine and xylazine followed 20 minutes later by insulin upon glucose metabolism and plasma insulin concentrations was examined in three cows. After doses of 0.18 mg per kg xylazine given intramuscularly (IM) or 0.15 mg per kg given intravenously (IV) hepatic glucose production increased, plasma insulin concentrations decreased to 25 to 33 per cent of control values, and there was a prolonged hyperglycaemia. When 200 units of soluble insulin were given 20 minutes after similar doses of xylazine there was a rapid fall in blood glucose and a reduction in the rate of glucose production by the liver. Xylazine-induced hyperglycaemia arose from a combination of increased hepatic glucose production and reduced plasma insulin concentrations. Peripheral tissues were still responsive to insulin and when adequate insulin was available blood glucose concentrations rapidly decreased.

Animals↗

Pharmacokinetics of xylazine, 2,6-dimethylaniline, and tolazoline in tissues from yearling cattle and milk from mature dairy cows after sedation with xylazine hydrochloride and reversal with tolazoline hydrochloride.

Xylazine hydrochloride was administered i.m. at 0.35 mg/kg to 13 steers and 10 lactating dairy cows at Time 0. Ten minutes later, tolazoline hydrochloride was given i.v. at 4 mg/kg. Tissue and milk samples were analyzed using gas chromatography with nitrogen and phosphorous detection to determine concentrations of xylazine, 2,6-dimethylaniline (a toxic metabolite of xylazine), and tolazoline (at various intervals). Concentrations of xylazine and 2,6- dimethylaniline were below the limit of quantitation (10 microg/kg) by 72 hours in tissues and 12 hours in milk. The concentration of tolazoline was below 10 microg/kg by 96 hours in tissues and 48 hours in milk. Based on the results of these residue studies submitted by the sponsoring agency to the Ministry of Agriculture and Forestry in New Zealand, withholding periods for both xylazine hydrochloride and tolazoline hydrochloride injection were established.

Adrenergic alpha-Agonists↗

Evaluation of lidocaine, xylazine, and a combination of lidocaine and xylazine for epidural analgesia in llamas.

Epidural analgesia was achieved at weekly intervals in 6 adults llamas by injection of 2% lidocaine, 10% xylazine, and a combination of 2% lidocaine/10% xylazine at the sacrococcygeal junction. Analgesia was determined by lack of response to pin prick or hemostat pressure in the perineal area. Ataxia could not be accurately evaluated because of the llamas' tendency to assume sternal recumbency when restrained. Time to onset of analgesia was not different between lidocaine (3.16 +/- 0.31 minutes) and lidocaine/xylazine (3.50 +/- 0.56 minutes), but results for both groups were different than those for xylazine (20.67 +/- 3.37 minutes). Duration of analgesia was different among all groups (lidocaine, 71.0 +/- 6.15 minutes; xylazine, 186.83 +/- 14.86 minutes; lidocaine/xylazine, 325.83 +/- 29.39 minutes). Mild sedation developed in 4 llamas given xylazine alone. Lidocaine/xylazine caused mild sedation in 2 llamas and moderate sedation in 1 llama. Significant changes in pulse or respiratory rates were not observed among drugs, but changes were observed over time with all drugs. As has been reported in other species, lidocaine/xylazine provided rapid onset and prolonged duration of analgesia.

Analgesia, Epidural↗

Clinical effects of azaperone-metomidate, as compared to propionylpromazine-xylazine-metomidate or xylazine-ketamine combinations in anaesthesia of dogs.

Eighteen dogs of Tanzanian breeds divided into three groups of 6 were anaesthetized using either azaperone-metomidate (2 mg/kg, i.m. and 10 mg/kg i.p., respectively), propionyl promazine-xylazine-metomidate (2 mg/kg i.m., 1 mg/kg i.m. and 10 mg/kg i.p., respectively), or xylazine-ketamine (1 mg/kg i.m. and 11 mg/kg i.m., respectively). The clinical effects on respiration rate, heart rate and body temperature were studied until recovery. Hypersensitivity to noise was associated with azaperone metomidate anaesthesia. The other combination produced a smooth and uneventful induction and recovery from anaesthesia. Muscle relaxation and analgesia were adequate in all groups. Duration of xylazine-ketamine anaesthesia was shortest (30 +/- 5 minutes) followed by azaperone metomidate (50 +/- 15 minutes) and the longest duration was with propionyl promazine-xylazine-ketamine (120 minutes). Azaperone and metomidate was associated with marked increases in cardiac and respiration rates and marked hypothermia, which persisted throughout. Minimal changes were observed in the other combinations. Azaperone-metomidate seems to be preferable due to the moderate period of anaesthesia adequate for most operations. However, all the three combinations offer a practical application because of the convenient route of administration.

Anesthesia↗

Effects of ketamine, xylazine, and a combination of ketamine and xylazine in Pekin ducks.

Effects of ketamine, xylazine, and a combination of ketamine and xylazine were studied in 12 male Pekin ducks (7 to 12 weeks old; mean [+/- SD] body weight, 3.1 +/- 0.3 kg). After venous and arterial catheterization and fixation of a temperature probe in the cloaca, each awake duck was confined, but not restrained, in an open box in a dimly lit room. Blood pressure and lead-II ECG were recorded. Three arterial blood samples were collected every 15 minutes over a 45-minute period (control period) and were analyzed for pHa, PaCO2 and PaO2. After the control period, each duck was assigned at random to 1 of 3 drug groups: (1) ketamine (KET; 20 mg/kg of body weight, IV), (2) xylazine (XYL; 1 mg/kg, IV), and (3) KET + XYL (KET 20 mg/kg and XYL, 1 mg/kg; IV). Measurements were made at 1, 5, 10, 15, 30, 45, 60, and 90 minutes after drug administration. All ducks survived the drug study. Cloacal temperature was significantly (P less than or equal to 0.05) increased above control cloacal temperature at 90 minutes after the administration of ketamine, and from 10 through 90 minutes after administration of ketamine plus xylazine. In ducks of the KET group, pHa, PaCO2, and PaO2, remained unchanged after administration of the drug. In ducks of the XYL group, pHa and PaO2 decreased significantly (P less than or equal to 0.05) from control values for all time points up to and including 15 minutes after drug administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Comparison of Telazol, Telazol-ketamine, Telazol-xylazine, and Telazol-ketamine-xylazine as chemical restraint and anesthetic induction combination in swine.

The use of Telazol (T, tiletamine and zolazepam, 4.4 mg T/kg) alone, Telazol-ketamine (TK, 4.4 mg T/kg and 2.2 mg K/kg), Telazol-xylazine (TX, 4.4 mg T/kg, 2.2 mg X/kg), and Telazol-ketamine-xylazine (TKX, 4.4 mg T/kg, 2.2 mg K/kg, and 2.2 mg X/kg) as chemical restraint and anesthetic induction combination was compared in pigs. Forty mixed-breed healthy pigs (24.4 +/- 5.6 kg, mean +/- SD) were randomly assigned to the four treatment groups (T, TK, TX, TKX) with 10 pigs in each group. All the anesthetics were premixed by adding sterile water, ketamine, xylazine, or xylazine and ketamine directly into the Telazol vial and given as a single intramuscular injection. All four anesthetic combinations induced a rapid onset of sternal recumbency within 1.76 +/- 1.0 minutes and lateral recumbency within 3.02 +/- 2.2 minutes in pigs after intramuscular injection; there was no significant difference among treatments. The combinations TX and TKX induced analgesia (as evident by a lack of response to needle prick in the middle portion of the pinna and flank regions) duration of 29.0 +/- 11.0 and 36.0 +/- 12.2 minutes, respectively, and ability to tolerate tracheal intubation (as evident by lack of coughing and chewing response to a laryngoscope) for a period of 34.0 +/- 8.4 and 39.0 +/- 9.9 minutes, respectively. The combinations T and TK did not induce analgesia nor conditions suitable for intubation. Duration of lateral recumbency was 29.9 +/- 10, 33.1 +/- 6.9, 52.2 +/- 6.9, and 61.5 +/- 10.7 minutes in T-, TK-, TX-, and TKX-treated pigs, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia Recovery Period↗

Chemical immobilization of rhebok (Pelea capreolus) with carfentanil-xylazine or etorphine-xylazine.

Twelve adult rhebok (Pelea capreolus) were immobilized using a combination of 0.4 mg/kg xylazine and either 0.01 mg/kg of carfentanil (n = 6) or 0.01 mg/kg etorphine (n = 6), delivered i.m. using a remote injection system. Induction and recovery times, heart rate, respiratory rate, rectal temperature, oxygen saturation, end-tidal CO2 (ETCO2), anesthetic depth, indirect blood pressure, and arterial blood gases were recorded. Rhebok were not intubated but nasal oxygen was administered. Forty minutes after induction, anesthesia was antagonized with naltrexone and yohimbine. Mean initial heart rate was significantly higher in the carfentanil group than in the etorphine group. Mean initial oxygen saturation was consistent with hypoxia in both the carfentanil group and the etorphine group. In both groups, arterial pH decreased and partial pressure of carbon dioxide increased during the first 15 min of anesthesia, and values were similar in both groups. These findings were consistent with respiratory acidosis and decreased ventilation. Values for respiratory rate, temperature, oxygen saturation, ETCO2, and blood pressure were similar for both groups at all time periods. During the first 5 min of anesthesia, rhebok in the carfentanil group were more responsive to stimuli than rhebok in the etorphine group. After administration of antagonists, time to first arousal was significantly shorter in the etorphine group than in the carfentanil group. Although cardiopulmonary values were similar for the two groups, rhebok in the carfentanil group were at a comparatively lighter plane of anesthesia, and some individuals in this group required additional manual and chemical restraint for medical procedures to be performed. In conclusion, for captive adult rhebok, 0.01 mg/kg of etorphine and 0.4 mg/kg of xylazine are recommended over 0.01 mg/kg carfentanil and 0.4 mg/kg xylazine because of qualitatively better anesthetic episodes and shorter recovery times.

Adrenergic alpha-Agonists↗

[Intravenous anesthesia in the horse: comparison of xylazine-ketamine and xylazine-tiletamine-zolazepam combinations].

Intravenous anesthesia in the horse: Comparison of xylazine-ketamine and xylaxine-tiletamine-zolazepam combinations. Six healthy adult horses were anesthetized twice at random with following intravenous combinations: 1.1 mg/kg of body weight (BW) of xylazine followed by 2.2 mg/kg BW of ketamine (X-K) and 1.1 mg/kg BW of xylazine followed by 1.65 mg/kg BW of tiletamine-zolazepam (X-TZ). The modifications of some cardiorespiratory parameters and the duration of anesthesia were evaluated and compared for the 2 protocols used. Few significant differences were observed between the 2 protocols in regard to the cardiorespiratory parameters measured. The respiratory rate was lower (7 breaths per minute) and the heart rate was higher (34 beats per minute) with the X-TZ combination. The duration of anesthesia with this technique was 33 +/- 3 minutes (X +/- Sx) and longer than with X-K (18 +/- minutes (X +/- Sx)). Superficial analgesia lasted 14,5 +/- 3 minutes with the X-K combination and 31,7 +/- 3,2 minutes for the X-TZ combination. The 2 protocols are associated with a reduction of PaO2.

Anesthesia, Intravenous↗

Xylazine and xylazine-ketamine in dogs.

The cardiopulmonary consequences of IV administered xylazine (1.0 mg/kg) followed by ketamine (10 mg/kg) were evaluated in 12 dogs. Xylazine caused significant decreases in heart rate, cardiac output, left ventricular work, breathing rate, minute ventilation, physiologic dead space, oxygen transport, mixed venous partial pressure of oxygen, and oxygen concentration. It caused significant increases in systemic blood pressure, central venous pressure, systemic vascular resistance, tidal volume, and oxygen utilization ratio. The subsequent administration of ketamine was associated with significant increases in heart rate (transient increase), cardiac output, the alveolar-arterial PO2 gradient and venous admixture (transient increase), and arterial PCO2 (transient increase). It caused significant decreases in stroke volume (transient decrease), left ventricular stroke work (transient decrease), effective alveolar ventilation, arterial PO2 and oxygen content (transient decrease).

Anesthesia, General↗