Medetomidine Ketamine Research Articles

Comparison of intramuscular alfaxalone with medetomidine-ketamine for inducing anaesthesia in Trachemys scripta spp. undergoing sterilization

ObjectiveTo compare the effect of two anaesthetic protocols on heart rate (HR), time to muscle relaxation and tracheal intubation and time to surgical plane of anaesthesia, in Trachemys scripta spp. undergoing oophorectomy. Study designProspective randomized clinical study. AnimalsA total of 43 healthy female turtles. MethodsMorphine (1.5 mg kg–1) was injected subcutaneously 2 hours before anaesthesia induction. The turtles were randomly administered either medetomidine (0.2 mg kg–1) and ketamine (10 mg kg–1) (group MK; n = 23) or alfaxalone (20 mg kg–1) (group A; n = 20) intramuscularly followed by bupivacaine (2 mg kg–1) administered subcutaneously along the incision site. Anaesthesia was maintained with isoflurane delivered in oxygen (100%). HR and the anaesthetic depth score (ADS) were recorded every 5 minutes from induction to recovery. A Friedman test followed by Wilcoxon tests with Bonferroni adjustment were used to compare these non-parametric data (HR and ADS) between groups and over time. Time to muscle relaxation of neck and limbs (TMR), tracheal tube insertion (TTTI) and stage of surgical anaesthesia (TADS≤3) were recorded and compared between groups using a Welch’s t test after logarithmic transformation. ResultsMedian values of TMR, TTTI and TADS≤3 were 4, 9.5 and 25 minutes in group A, respectively, and 14, 20 and 35 minutes in group MK (TMR, TTTIp ≤ 0.0001; TADS≤3p = 0.001). Plane of anaesthesia was significantly deeper in group A than in group MK for the first 20 minutes (p < 0.01). HR at 10 and 15 minutes post injection was significantly lower in group MK (28 beats minute–1) than in group A (36 and 34 beats minute–1) (p < 0.02). Conclusions and clinical relevanceAfter intramuscular injection in Trachemys scripta spp., tracheal intubation, muscle relaxation and a surgical plane of anaesthesia developed faster with alfaxalone than medetomidine–ketamine.

Comparison of Anesthetic Efficacy of Intranasal Administration of Medetomidine / Ketamine and Diazepam / Ketamine Combinations on New Zealand White Rabbits

This study aimed to determine the anesthetic efficacy of intranasal medetomidine/ketamine and diazepam/ketamine combinations in New Zealand White rabbits. For this purpose, 12 adult New Zealand White rabbits weighing 2.3‐4.1 kg were used by randomly dividing the animals into two groups of six animals: Medetomidine ‐ Ketamine (MK) and Diazepam ‐ Ketamine (DK). Intranasally, medetomidine (0.2 mg kg‐1) and ketamine (10 mg kg‐1) combination was administered to the MK group and, diazepam (1 mg kg‐1) and ketamine (10 mg kg‐1) to the DK group. Before and 5, 10, 15, 20, 25, 30, 45, and 60 minutes after anesthesia, loss, and recovery of the reflexes were evaluated. Onset and duration of the anesthesia, duration of the surgical anesthesia, and the total anesthesia time were also recorded. Loss and recovery time of reflexes was shorter in the DK group compared to the MK group. Respiratory rate, heart rate, and SpO2 decreased as expected in both groups but all parameters, especially SpO2, were lower in the MK group comparing the DK group. These results showed that both MK and DK combinations administered IN provide anesthesia in the time and depth that minor surgical procedures and clinical applications could be performed. Although it seems promising considering its practicality and anesthetic efficacy, it is clear that more detailed studies with more animals are needed before the safety of these protocols can be established.Their use, recommended for routine clinical procedures when considered SpO2, was severely decreased, especially in the MK group.

The impact of vatinoxan on medetomidine–ketamine–midazolam immobilization in Patagonian maras (Dolichotis patagonum)

ObjectiveTo compare cardiovascular and ventilatory effects, immobilization quality and effects on tissue perfusion of a medetomidine–ketamine–midazolam combination with or without vatinoxan (MK-467), a peripherally acting α2-adrenoceptor antagonist. Study designRandomized, blinded, crossover study. AnimalsA group of nine healthy Patagonian maras (Dolichotis patagonum). MethodsMaras were immobilized twice with: 1) medetomidine hydrochloride (0.1 mg kg–1) + ketamine (5 mg kg–1) + midazolam (0.1 mg kg–1) (MKM) + saline or 2) MKM + vatinoxan hydrochloride (0.8 mg kg–1), administered intramuscularly. Drugs were mixed in the same syringe. At 20, 30 and 40 minutes after injection, invasive blood pressure, heart rate, respiration rate, end-tidal CO2, haemoglobin oxygen saturation, and muscle oxygenation were measured, arteriovenous oxygen content difference was calculated. Muscle tone, jaw tone, spontaneous blinking and palpebral reflex were evaluated. Times to initial effect, recumbency, initial arousal and control of the head were recorded. Paired t test, Wilcoxon matched-pairs signed rank test and analysis of variance were used to compare protocols; (p < 0.05). ResultsVatinoxan significantly reduced systolic (p = 0.0002), mean (MAP; p < 0.0001) and diastolic (p < 0.0001) arterial blood pressures between 20 and 40 minutes. MAPs at 30 minutes (mean ± standard deviation) with MKM and MKM + vatinoxan were 105 ± 12 and 71 ± 14 mmHg, respectively. Without vatinoxan, four animals were hypertensive (MAP > 120 mmHg), whereas with vatinoxan, four animals were hypotensive (MAP < 60 mmHg). Muscle and jaw tone were significantly more frequently present with MKM (both p = 0.039). Other measurements did not significantly differ between protocols. Conclusions and clinical relevanceIn Patagonian maras, vatinoxan attenuated the increase in blood pressure induced by medetomidine. Muscle and jaw tone were more frequently present with MKM, indicating that quality of immobilization with vatinoxan was more profound.

ANESTHESIA WITH MEDETOMIDINE-KETAMINE AND DEXMEDETOMIDINE-KETAMINE IN MOUNTAIN GORILLAS (GORILLA BERINGEI BERINGEI).

Between December 2002 and September 2017, 125 anesthetic procedures involving free-living and orphaned captive mountain gorillas (Gorilla beringei beringei) were performed in the Virunga Massif and Bwindi Impenetrable Forest in East-Central Africa. Of these 125 immobilizations, 114 records were complete enough for inclusion into this study. Anesthetic and physiologic data from these 114 cases were analyzed, of which 57 used medetomidine-ketamine and 57 used dexmedetomidine-ketamine administered intramuscularly. With the use of estimated weights, the mean induction dosage (mg/kg ± SD) for medetomidine was 0.033 ± 0.003 (n = 42), for dexmedetomidine 0.018 ± 0.005 (n = 53), and for ketamine 3.66 ± 0.95 (n = 95). Mean time from injection of induction dose to recumbency was 6.8 ± 3.1 min (n = 74). Atipamezole was administered intramuscularly to reverse anesthesia. First signs of recovery occurred at 5.0 ± 4.0 min, and full recovery was 19.0 ± 17.0 min after administration of the reversal agent. No significant differences in physiologic parameters or anesthetic time variables were noted between healthy and unhealthy individuals. Mean heart rate was 72.0 ± 17.6 beats/min (n = 83) and mean oxygen saturation was 96.5% ± 4.2 (n = 62). Mean respiratory rate was 27 ± 9 breaths/min (n = 84) and mean body temperature 36.6°C ± 1.2 (n = 61). The current protocol has several advantages for field use in this species given its quick induction, few observed side effects, and ability to reverse so that the animal can return more quickly to its social group.

Efficacy comparison of intraperitoneal anaesthesia and post-operative analgesia regimens in laboratory rats.

Effective and safe anesthesia for rodents has long been a leading concern among biomedical researchers. Intraperitoneal injection constitutes an alternative to inhalant anesthesia. The aim of this study was to identify a safe, reliable, and effective anesthesia and postoperative analgesia protocol for laboratory rats exposed to painful procedures. Twenty-seven female Wistar rats in an ongoing study that required surgery were randomized into groups for three different intraperitoneal anesthesia protocols and three different analgesia regimens. The anesthesia groups were (1) medetomidine + ketamine (MK), (2) ketamine + xylacine (KX), and (3) fentanyl + medetomidine (FM). Three analgesia groups were equally distributed among the anesthesia groups: (1) local mepivacaine + oral ibuprofen (MI), (2) oral tramadol + oral ibuprofen (TI), and (3) local tramadol + oral tramadol + + oral ibuprofen (TTI). A core was assigned to measure anesthesia (0-3) and analgesia (0-2) effectiveness; the lower the score, the more effective the treatment. The mean MK score was 0.44 versus 2.00 for FM and 2.33 for KX. Mean score for analgesia on the first postoperative day was TTI (4.66) TI (9.13), and MI (10.14). Mean score 48 hours after surgery was TTI (3.4), TI (6.71), and MI (9.5). These differences were statistically significant. MK was shown to be a reliable, safe, and effective method of anesthesia. The TTI analgesia regimen is strongly recommended in light of these results.

COMPARISON OF ANESTHESIA OF ADULT GIRAFFE (GIRAFFA CAMELOPARDALIS) USING MEDETOMIDINE-KETAMINE WITH AND WITHOUT A POTENT OPIOID.

Two anesthetic protocols in adult giraffe were compared by retrospective study. Thirteen anesthesia records for medetomidine-ketamine (MK) and seven for medetomidine-ketamine with a potent opioid (MKO) were evaluated for differences in demographic, behavioral, drug, and respiratory parameters. Giraffe stood significantly more quickly with MKO vs MK though MK animals were physically restrained to preclude premature standing as part of normal recovery practices (5.5 min vs 21.4 min, P = 0.01). Regurgitation was recorded in 5/13 and resedation in 4/13 MK animals. The range of values for blood lactate was higher in MKO (5.18-11.25 mM/L) than in MK giraffe (0.78-6.08 mM/L). Despite limitations of a retrospective study, both MK and MKO giraffe anesthesia protocols exhibit benefits and side effects. Awareness and management of these factors will improve outcomes until standardized, prospective studies of giraffe immobilization offer more comprehensive guidance on protocol selection.

Clinical evaluation of intranasal medetomidine–ketamine and medetomidine–S(+)-ketamine for induction of anaesthesia in rabbits in two centres with two different administration techniques

ObjectiveThe aim was to compare efficacy and side effects of induction with medetomidine–ketamine or medetomidine–S(+)-ketamine by intranasal (IN) instillation in rabbits and to evaluate both protocols during subsequent isoflurane anaesthesia. Study designProspective, blinded, randomized experimental study in two centres. AnimalsEighty-three healthy New Zealand White rabbits undergoing tibial or ulnar osteotomy. MethodsMedetomidine (0.2 mg kg−1) with 10 mg kg−1 ketamine (MK) or 5 mg kg−1 S(+)-ketamine (MS) was administered IN to each rabbit in a randomized fashion. In Centre 1 (n = 42) rabbits were held in sternal recumbency, and in Centre 2 (n = 41) in dorsal recumbency, during drug instillation. Adverse reactions were recorded. If a rabbit swallowed during endotracheal intubation, half of the initial IN dose was repeated and intubation was re-attempted after 5 minutes. Anaesthesia was maintained with isoflurane. Heart rate, blood pressure, endtidal carbon dioxide concentration and blood gases were recorded. Data were analysed using Student's t-test, Mann–Whitney test and Fisher's exact test. ResultsIn all, 39 animals were assigned to the MK group and 44 to the MS group. Two rabbits in the MS group held in dorsal recumbency died after instillation of the drug. Eight (MK) and 11 rabbits (MS) were insufficiently anaesthetized and received a second IN dose. One rabbit in MK and three in MS required an isoflurane mask induction after the second IN dose. There were no significant differences between treatments for induction, intraoperative data, blood gas values and recovery data. Conclusion and clinical relevanceThis study indicated that medetomidine–ketamine and medetomidine-S(+)-ketamine were effective shortly after IN delivery, but in dorsal recumbency IN administration of S(+)-ketamine led to two fatalities. Nasal haemorrhage was noted in both cases; however, the factors leading to death have not been fully elucidated.

Propofol–medetomidine–ketamine total intravenous anaesthesia in thiafentanil–medetomidine-immobilized impala (Aepyceros melampus)

ObjectiveTo characterize a propofol–medetomidine-ketamine total intravenous anaesthetic in impala (Aepyceros melampus). Study designProspective clinical study. AnimalsTen adult female impala. Materials and methodsImpala were immobilized at 1253 m above sea level with 2.0 mg thiafentanil and 2.2 mg medetomidine via projectile darts. Propofol was given to effect (0.5 mg kg−1 boluses) to allow endotracheal intubation, following which oxygen was supplemented at 2 L minute−1. Anaesthesia was maintained with a constant-rate infusion of medetomidine and ketamine at 5 μg kg−1 hour−1 and 1.5 mg kg−1 hour−1, respectively, and propofol to effect (initially 0.2 mg kg−1 minute−1) for 120 minutes. The propofol infusion was titrated according to reaction to nociceptive stimuli every 15 minutes. Cardiopulmonary parameters were monitored continuously and arterial blood gas samples were analysed intermittently. After 120 minutes' maintenance, the thiafentanil and medetomidine were antagonized using naltrexone (10:1 thiafentanil) and atipamezole (5:1 medetomidine), respectively. ResultsAll impala were successfully immobilized. The median dose [interquartile range (IQR)] of propofol required for intubation was 2.7 (1.9–3.3) mg kg−1. The propofol–medetomidine–ketamine combination abolished voluntary movement and ensured anaesthesia for the 120 minute period. Propofol titration showed a generally downward trend. Median (IQR) heart rate [57 (53–61) beats minute−1], respiratory rate [10 (9–12) breaths minute−1] and mean arterial blood pressure [101 (98–106) mmHg] were well maintained. Arterial blood gas analysis indicated hypoxaemia, hyper- capnia and acidaemia. Butorphanol (0.12 mg kg−1) was an essential rescue drug to counteract thiafentanil-induced respiratory depression. All impala regurgitated frequently during the maintenance period. Recovery was calm and rapid in all animals. Median (IQR) time to standing from antagonist administration was 4.4 (3.2–5.6) minutes. Conclusions and clinical relevanceA propofol–medetomidine–ketamine combination could provide adequate anaesthesia for invasive procedures in impala. The propofol infusion should begin at 0.2 mg kg−1 minute−1 and be titrated to clinical effect. Oxygen supplementation and airway protection with a cuffed endotracheal tube are essential.

Monitoring the stress-level of rats with different types of anesthesia: A tail-artery cannulation protocol

IntroductionFunctional MRI in rats under anesthesia can largely minimize motion artifacts and attenuate the stress of the animal. However, two issues remain to be clarified and improved. First, fMRI results obtained with different types of anesthesia during surgical preparation and imaging show a large variability, which could be caused by the variable stress level of the rodents. Second, the most common surgical procedure used for anesthesia, blood gas analysis and mean arterial blood-pressure (MABP) monitoring is the femoral vein and artery catheterization that makes longitudinal studies difficult. Methods:In order to examine the variability of the stress level with three different anesthesia protocols using isoflurane (Iso), medetomidine–ketamine (MK) or propofol–remifentanil (PR), we measured the plasma corticosterone (CORT) concentration with 125I-radioimmunoassay in blood samples collected prior to, immediately after and 60min after surgery. Tail-artery and vein catheterization was adapted for long-term monitoring of MABP with periodic blood sampling and is proposed as a less invasive and technically simple alternative to femoral vessel catheterization in fMRI preparation protocols. Results:We show that the CORT concentration depends on the anesthesia protocol with both alternatives providing more efficient stress reduction than the protocol using Iso. However, only the protocol using PR achieved a significant hormone reduction during surgery. Stress was not reliably manifested in changes in heart-rate and breathing-rate. Anesthesia and strain related changes in these two physiological parameters may be assigned to the pharmacological effects of the premedication and anesthetic agents. The results indicate also that MABP can be monitored over a long period of time (e.g. functional imaging session) through an arterial access point in the rat tail after cannulation with the proposed procedure. Discussion and conclusion:Animals can experience stress during fMRI preparation protocols without obvious signs in commonly monitored physiological parameters. Our results challenge the efficiency of surgical protocols using Iso as mono-anesthetic agent, even when extended with topical analgesia. It was demonstrated that the CORT-based stress-level measurement through tail-artery cannulation can be used for developing anesthesia protocols (i.e. the presented PR protocol) when setting up future fMRI studies. The proposed surgical method for the tail is expected to facilitate longitudinal fMRI studies with permanent arterial access.

Comparison of xylazine–ketamine and medetomidine–ketamine anaesthesia in the Iberian ibex (Capra pyrenaica)

A comparison was made between two anaesthetic combinations in 35 free-ranging adult Iberian ibexes (Capra pyrenaica), from May to December 2005. Sixteen ibexes (10 males, 6 females) were captured using xylazine–ketamine (3.0 ± 0.4 + 3.0 ± 0.4 mg/kg) and 19 ibexes (12 males, 7 females) with medetomidine–ketamine (0.10 ± 0.02 + 2.1 ± 0.3 mg/kg). Anaesthetic times were evaluated, as well as clinical variables (respiratory and heart rates, rectal temperature, haemoglobin oxygen saturation), haematological and biochemical variables, at the time of induction and after 1 h. The heart rate of ibex immobilized with medetomidine–ketamine was higher than those immobilized with xylazine–ketamine. Stabilization of the heart rate of ibex immobilized with medetomidine–ketamine came earlier than those immobilized with xylazine–ketamine. Rectal temperature decreased and stabilized in both groups, but earlier in the xylazine–ketamine group, and hypoxemia was observed in both groups. The white blood cell count of ibex immobilized with medetomidine–ketamine was lower than those immobilized with xylazine–ketamine throughout anaesthesia, while sodium concentration was higher only after 1 h of anaesthesia. In ibex immobilized with xylazine–ketamine, the neutrophil count, serum creatinine kinase activity and aspartate aminotransferase activity increased after 1 h of immobilization, while triglycerides decreased. Changes found in haematological and biochemical variables suggest no major differences in the different drug combinations used, but clinical findings of this study, as well as hypoxemia, hypothermia and bradycardia, were important records that should be taken into account when performing a safe operation.

Evaluation of Medetomidine–Ketamine–Butorphanol Anesthesia with Atipamezole–Naltrexone Antagonism in Captive Male Guanacos (Lama guanicoe)

Seven captive adult male guanacos (Lama guanicoe) weighing 112.0 +/- 10.9 kg (mean +/- standard deviation) were anesthetized with a combination of medetomidine (90.0 +/- 8.8 microg/kg), ketamine (2.7 +/- 0.3 mg/kg), and butorphanol (0.3 +/- 0.03 mg/kg) administered intramuscularly to evaluate its anesthetic and cardiopulmonary effects. Inductions were smooth and rapid, with a mean time to initial effect of 3 +/- 1.5 min and a mean time to recumbency of 5.1 +/- 3.1 min. Anesthesia was predictable, smooth, and characterized by excellent muscle relaxation. Spontaneous ventilation was maintained throughout anesthesia in all animals. Marked bradycardia ranging from 24 to 52 beats/min was noted across all time points for all individuals. Median heart rates decreased during the procedures, but median heart rate, temperature, respiratory rate, and end-tidal carbon dioxide values over the 20 min monitoring period were not significantly different. Mean arterial partial pressure of oxygen (PaO2) on initial sampling was 65.9 +/- 14.8 mm Hg, with six of seven animals exhibiting hypoxemia (PaO2 <80 mm Hg). After oxygen supplementation for 20 min, mean PaO2 values showed statistically significant increases to a mean value of 127.7 +/- 32.4 mm Hg (P = 0.0014). Mean arterial partial pressure of carbon dioxide (PaCO2) showed a significant increase over the monitoring period (P = 0.0004), and mild hypoventilation (PaCO2 >45 mm Hg) was noted in four animals. Mean total duration of procedure time was 23.3 +/- 3.3 min. All guanacos received 0.45 +/- 0.04 mg/kg atipamezole and 2.7 +/- 0.25 mg/kg naltrexone administered intramuscularly for anesthetic antagonism. Recoveries were smooth and uncomplicated. Mean time to sternal recumbency after antagonist administration was 7.7 +/- 4.5 min, and time to successful standing was 12.9 +/- 5.0 min, with all animals standing on first attempt.

Atipamezole changes the antinociceptive effects of butorphanol after medetomidine–ketamine anaesthesia in rats

ObjectiveTo investigate the effects of atipamezole administered before butorphanol, on tail-flick latency (TFL) and also following medetomidine–ketamine anaesthesia in rats. Study designProspective, randomized experimental study. AnimalsThirty-four adult male Sprague–Dawley rats weighing 260–390 g. MethodsTFL in 50 °C water was used to measure antinociception. In the first experiment, rats received saline (n = 5) or atipamezole (n = 5) followed by butorphanol treatments. In the second experiment, three groups of rats received saline (n = 8), atipamezole (n = 8) or atimpamezole (n = 8) followed by butorphanol 60 minutes after medetomidine–ketamine administration. ResultsIn the first experiment, butorphanol significantly increased TFL compared to baseline. Atipamezole significantly decreased this effect. In the second experiment, TFL was significantly increased after recovery from medetomidine–ketamine anaesthesia compared to baseline. This was almost completely blocked by atipamezole. Atipamezole with butorphanol after recovery from the anaesthesia significantly reduced TFL compared to saline but still significantly increased TFL compared to the baseline. Conclusion and clinical relevanceAtipamezole attenuated the analgesic effects of butorphanol. When postoperative atipamezole is used to hasten recovery from anaesthesia in rats, it may interfere with the postoperative analgesic effect of butorphanol.

Comparison of the effects of three different combinations of general anesthetics on the electroretinogram of dogs

The objective of this study is to compare the effects of three different anesthetic combinations on the electroretinogram in the same animals under similar laboratory conditions. Thiopental-isoflurane (TI), medetomidine-ketamine (MK), and xylazine-ketamine (XK) were used on each of 12 healthy miniature schnauzer dogs (MS) with a period of at least 3 weeks in between subsequent anesthesia protocols, using the Dog Standard Protocol. The scotopic ERGs consisted of scotopic low stimulus strength (S) responses designated S1, S2, S3, S4, and S5, at 1, 5, 10, 15, and 20 min after dark adaptation, respectively, and scotopic standard stimulus strength (S-ST) responses. The photopic ERGs consisted of a photopic single flash (P) response and 31 Hz flicker (P-FL) responses. For S-ST (2.5 cd s/m(2)), the amplitude of the a-wave using TI was significantly lower than that using MK (adjusted P = 0.05) and XK (adjusted P = 0.03), and the implicit time of the a-wave was significantly shorter than that using MK (adjusted P = 0.04). For P (2.5 cd s/m(2)), the amplitude of the b-wave using XK was significantly higher than that using MK (adjusted P = 0.01). The implicit times of the b-wave using TI was significantly longer and shorter than that of MK for S1, S2 and P-FL and for S4 and S-ST, respectively, and than that of XK for S2 and P-FL and for S5 and S-ST, respectively. The results of the present study showed that TI affected both the amplitude and the implicit time of the a-wave for S-ST and the implicit time of the b-wave relatively more so than was the case when using XK or MK. Therefore, it appears that either XK or MK could be advantageous to use rather than TI for clinical studies.

Anesthetic and cardiopulmonary effects of intramuscular morphine, medetomidine, ketamine injection in dogs

ObjectiveTo determine the quality and duration of anesthesia and the cardiopulmonary effects of a morphine, medetomidine, ketamine (MMK) combination administered intramuscularly (IM) to dogs. Study designDescriptive injectable anesthetic protocol evaluation. AnimalsEight intact adult Beagle dogs: five males, three females. MethodsThe electrocardiogram, heart rate, direct arterial blood pressure, and core body temperature were monitored in eight chronically instrumented dogs. Each dog received 0.2 mg kg−1 morphine sulfate, 20 μg kg−1 medetomidine hydrochloride, and 5 mg kg−1 ketamine hydrochloride IM. Anesthetic and analgesic effects (clamping the tail and metatarsus) were categorized, and the times to lateral recumbency, orotracheal intubation, extubation, and sternal recumbency were recorded. Respiratory, cardiovascular, temperature, and acid-base variables were recorded 5 minutes before, and 3, 10, 20, 30, 45, 50, and 60 minutes after MMK. Atipamezole, 100 μg kg−1 IM, was administered 60 minutes after MMK administration and data recorded 10 minutes later. ResultsThe onset of anesthesia was uneventful and rapid. Time to lateral recumbency was 7.1 ± 4.1 minutes. The tracheas of four dogs were orally intubated in 5.1 ± 0.8 minutes. After MMK administration most dogs were unresponsive to noxious stimulation from 20 to 60 minutes and heart rate, cardiac index and venous blood pH were significantly decreased from baseline values. Arterial blood pressure increased initially and then returned to baseline values. Times to extubation (four dogs) and return to sternal recumbency after atipamezole administration were 2.8 ± 1.8 and 4.3 ± 4.4 minutes, respectively. ConclusionThe IM administration of MMK produced anesthesia and analgesia in Beagle dogs. Hemodynamic data were within accepted normal values. Atipamezole administration produced rapid return to consciousness in all dogs. Clinical relevanceMorphine/medetomidine/ketamine may be used for minor medical and surgical procedures requiring short-term anesthesia and analgesia but it is not recommended for medical procedures that are painful.

A Comparative Clinical Study of Three Different Dosages of Intramuscular Midazolam–Medetomidine–Ketamine Immobilization in Cats

A low dose of midazolam-medetomidine-ketamine (MMK) combination was evaluated in three increasing dosages. Each of the 18 cats was randomly allocated for several times to one of four groups. Five minutes after premedication with intramuscular (IM) 0.04 mg/kg atropine, group A (n = 43), B (n = 40) and C (n = 28) all were anaesthetized with 0.5 mg/kg midazolam, combined with 10, 20 or 30 microg/kg medetomidine, and 1.0, 2.0 or 3.0 mg/kg ketamine, respectively, IM in one syringe. Group D (n = 11) received the established combination of 50 microg/kg medetomidine and 10.0 mg/kg ketamine for comparison. Because this study was in cooperation with a project on dental prophylaxis, cats had to be immobilized for approximately 1 h. Therefore, anaesthesia was prolonged with propofol to effect, if necessary. Duration of MMK anaesthesia was between 30 +/- 15, 45 +/- 19 and 68 +/- 28 min in groups A, B and C respectively. A significant decrease of respiratory rate was observed with increasing dosage, but venous carbon dioxide (pCO(2)) and pH values in combination with arterial oxygen saturation (SpO(2)) values were not alarming. The diastolic blood pressure particularly showed an increase. MMK combination A showed the best cardiovascular results, but it cannot be recommended due to disadvantages like a long induction time sometimes accompanied by excitations and the short duration of surgical immobilization. Dosage C in contrast had fewer side effects but less favourable cardiovascular results and a longer recovery period. However, either dosage B or C was suitable as a repeatable IM immobilization method for non-invasive procedures in healthy cats.

Anaesthetic and cardiopulmonary effects of intramuscular morphine, medetomidine and ketamine administered to telemetered cats.

The quality and duration of anaesthesia, cardiorespiratory effects and recovery characteristics of a morphine, medetomidine, ketamine (MMK) drug combination were determined in cats. Six healthy, adult female cats were administered 0.2 mg/kg morphine sulphate, 60 microg/kg medetomidine hydrochloride, and 5 mg/kg ketamine hydrochloride intramuscularly. Atipamezole was administered intramuscularly at 120 min after MMK administration. Time to lateral recumbency, intubation, extubation and sternal recumbency were recorded. Cardiorespiratory variables and response to a noxious stimulus were recorded before and at 3 min and 10 min increments after drug administration until sternal recumbency. The time to lateral recumbency and intubation were 1.9+/-1.2 and 4.3+/-1.2 min, respectively. Body temperature and haemoglobin saturation with oxygen remained unchanged compared to baseline values throughout anaesthesia. Respiratory rate, tidal volume, minute volume, heart rate, and blood pressure were significantly decreased during anaesthesia compared to baseline values. One cat met criteria for hypotension (systolic blood pressure <90 mmHg). End tidal carbon dioxide increased during anaesthesia compared to baseline values. All but one cat remained non-responsive to noxious stimuli from 3 to 120 min. Time to extubation and sternal recumbency following atipamezole were 2.9+/-1.1 and 4.7+/-1.0 min, respectively. MMK drug combination produced excellent short-term anaesthesia and analgesia with minimal cardiopulmonary depression. Anaesthesia lasted for at least 120 min in all but one cat and was effectively reversed by atipamezole.

ANESTHESIA OF CAPTIVE AFRICAN WILD DOGS (LYCAON PICTUS) USING A MEDETOMIDINE–KETAMINE–ATROPINE COMBINATION

Seven captive male African wild dogs (Lycaon pictus) weighing 25-32 kg each, were anesthetized by i.m. injection via hand syringe with a combination of 1.5 mg/kg ketamine, 40 microg/kg medetomidine, and 0.05 mg/kg atropine. Following endotracheal intubation, each animal was connected to a bain closed-circuit system that delivered 1.5% isoflurane and 2 L/min oxygen. Atipamezole (0.1 mg/kg i.v.; 0.1 mg/kg i.m.) was given at the end of each procedure (60 min following injection of medetomidine/ketamine/atropine). Time to sternal recumbency was 5-8 min. Times to standing after atipamezole administration were 8-20 min. This anesthetic regimen was repeated on three separate occasions (September 2000, February 2002, and October 2002) on all males to perform electroejaculation procedures. Each procedure was <80 min from injection to standing. Dogs showed excellent muscle relaxation during the procedures. Arterial blood samples were collected at 10-min intervals for blood gases in one procedure (September 2000). Separate venous samples were taken from each dog during each procedure for hematology and biochemistry. These values were within the normal range for this species. Arterial hemoglobin oxygen saturation (SpO2) and heart rate (HR) were monitored continuously in addition to other anesthesia monitoring procedures (body temperature, respiratory rate [RR], capillary refill time, blink response, pupil position, deep pain perception reflex). All dogs maintained relatively stable SpO2 profiles during monitoring, with a mean (+/-SD) SpO2 of 92% +/-5.4%. All other physiological variables (HR, RR, body temperature, blood pressure) were within normal limits. Following each procedure, normal behavior was noted in all dogs. All the dogs were reunited into the pack at completion of their anesthetic procedures. An injectable medetomidine-ketamine-atropine combination with maintenance by gaseous isoflurane and oxygen provides an inexpensive, reliable anesthetic for captive African wild dogs.

Comparison of two injectable anesthetic regimes in feral cats at a large-volume spay clinic

Same-day mass sterilization of feral cats requires rapid onset, short-duration anesthesia. The purpose of this study was to compare our current anesthetic protocol, Telazol–ketamine–xylazine (TKX) with medetomidine–ketamine–buprenorphine (MKB). Feral female cats received either IM TKX (n = 68; 0.25 mL cat−1; tiletamine 12.5 mg, zolazepam 12.5 mg, K 20 mg, and X 5 mg per 0.25 mL) or MKB (n = 17; M 40 µg kg−1, K 15 mg kg−1, and B 10 µg kg−1). Intervals measured included time from injection to recumbency, time to surgery, duration of surgery, and time from reversal of anesthesia (TKX: yohimbine 0.50 mg cat−1 IV; MKB: atipamezole 0.50 mg cat−1 IM) to sternal recumbency. Following instrumentation (Vet/Ox 4403 and Vet/BP Plus 6500), physiological measurements were recorded at 5-minute intervals, and included rectal temperature, heart rate (HR), respiratory rate (RR), SpO2 (lingual or rectal probes), and indirect mean arterial blood pressure (MAP) (oscillometric method). Nonparametric means were compared using Mann–Whitney U-tests. Parametric means were compared using a two-factorial anova with Bonferroni's t-tests. The alpha-priori significance level was p < 0.05. Values were mean ± SD. Body weight (TKX: 2.9 ± 0.5 kg, MKB: 2.7 ± 0.7 kg), time to recumbency (TKX: 4 ± 1 minutes, MKB: 3 ± 1 minutes), time to surgery (TKX: 28 ± 7 minutes, MKB: 28 ± 5 minutes), and duration of surgery (TKX: 11 ± 7 minutes, MKB: 8 ± 5 minutes) did not differ between groups. In contrast, MKB cats required less time from reversal to sternal recumbency (TKX: 68 ± 41 minutes, MKB: 7 ± 2 minutes) and were recumbent for shorter duration (TKX: 114 ± 39 minutes, MKB: 53 ± 6 minutes). Temperature decreased during the study in both groups, but overall temperature was higher in MKB cats (38.0 ± 0.95 °C) than in TKX cats (37.5 ± 0.95 °C). RR, HR, and SpO2 did not change during the study in either group. However, overall HR and RR were higher in TKX cats (RR: 18 ± 8 breaths minute−1, HR: 153 ± 30 beats minute−1) compared to MKB cats (RR: 15 ± 7 breaths minute−1, HR: 128 ± 19 beats minute−1). In contrast, overall SpO2 was lower in the TKX group (90 ± 6%) compared to the MKB group (94 ± 4%). MAP was also lower in the TKX group (112 ± 29 mm Hg) compared to that in the MKB group (122 ± 20 mm Hg). However, MAP increased in the TKX group during surgery compared to pre-surgical values, but did not change in the MKB group. The results of this study suggested that MKB might be more suitable as an anesthetic for the purpose of mass sterilization of feral female cats.

Surgical implantation of radio transmitters in arctic foxes (Alopex lagopus) on Svalbard, Norway.

Twelve captive wild-caught adult arctic foxes (Alopex lagopus) were anesthetized a total of 24 times for an equal number of surgical procedures involving implantation of heart rate (HR) and core body temperature transmitters (Tb) between October 1995 and April 1997. Xylazine-ketamine and medetomidine-ketamine anesthesia was used, resulting in an unacceptably high death rate. One out of four foxes anesthetized with xylazine-ketamine died, whereas two of nine foxes anesthetized with medetomidine-ketamine died out of a total of 20 surgical procedures. Durations of the surgeries for implantation of Tb transmitters and HR transmitters were 73 +/- 7 min and 95 +/- 13 min, respectively.

Reversible Chemical Restraint of Fishers with Medetomidine-Ketamine and Atipamezole

We chemically restrained wild-caught fishers (Martes pennanti) as part of a captive management protocol designed to facilitate veterinary evaluation, treatment of injuries, and conditioning on a high caloric diet prior to their reintroduction in Pennsylvania. We evaluated medetomidine-ketamine (MED-KET) and atipamezole (ATI) for reversible restraint of fishers (n = 10) by monitoring anesthesia intervals and physiologic response. We administered MED-KET to fishers at 0.4 mg MED combined with 20.0 mg KET to males, and 0.2 mg MED combined with 10.0 mg KET to females. Atipamezole at 2.0 mg to males and 1.0 mg to females or physiologic saline was administered to fishers approximately 20 min post-MED-KET injection, Atipamezole reversed the anesthetic effects of MED-KET, reducing mean down time, alert time, and recovery time, Physiologic response to MED-KET and ATI was generally unremarkable. However, we observed bradycardia in females restrained with MED-KET, and a hypotensive response in both sexes upon administration of ATI. Medetomidine-ketamine would be useful for field or clinical restraint of fishers because induction was rapid, recovery was calm, and there were no adverse physiologic responses. Medetomidine-ketamine may enable invasive procedures such as tooth removal or surgery. Atipamezole enhanced practical field application of MEDKET because it effectively and safely reversed MED-KET restraint of fishers.