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

Objective

The 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.

Evaluation of butorphanol–azaperone–medetomidine (BAM) in captive blesbok immobilization (Damaliscus pygargus phillipsi)

Objective

The fixed-dose combination of butorphanol, azaperone and medetomidine (BAM; 30, 12 and 12 mg mL^?1, respectively) with subsequent antagonism by naltrexone–atipamezole was evaluated for reversible immobilization of captive blesbok (Damaliscus pygargus phillipsi).

A clinical study to evaluate the cardiopulmonary characteristics of two different anaesthetic protocols for immobilization of healthy chimpanzees (Pan troglodytes)

Objective

To characterize the cardiopulmonary characteristics of two different anaesthetic protocols (tiletamine/zolazepam ± medetomidine) and their suitability for the immobilization of healthy chimpanzees undergoing cardiac assessment.

Effects of medetomidine,l‐methadone,and their combination on arterial blood gases in dogs

ObjectiveTo investigate the influence of l–methadone on medetomidine–induced changes in arterial blood gases and clinical sedation in dogs.Study designProspective experimental cross–over study (Latin square design).AnimalsFive 1–year–old purpose bred laboratory beagle dogs of both sexes.MethodsEach dog was treated three times: medetomidine (20 μg kg^?1 IV), l–methadone (0.1 mg kg^?1 IV) and their combination. Arterial blood was collected for blood gas analysis. Heart and respiratory rates were recorded, and clinical sedation and reaction to a painful stimulus were scored before drug administration and at various time points for 30 minutes thereafter.ResultsArterial partial pressure of oxygen decreased slightly after medetomidine administration and further after medetomidine/l–methadone administration (range 55.2–86.7 mmHg, 7.4–11.6 kPa, at 5 minutes). A slight increase was detected in arterial partial pressure of carbon dioxide after administration of l–methadone and medetomidine/l–methadone (42.6 ± 2.9 and 44.7 ± 2.4 mmHg, 5.7 ± 0.4 and 6.0 ± 0.3 kPa, 30 minutes after drug administration, respectively). Arterial pH decreased slightly after administration of l–methadone and medetomidine/l–methadone. Heart and respiratory rates decreased after administration of medetomidine and medetomidine/l–methadone, and no differences were detected between the two treatments. Most dogs panted after administration of l–methadone and there was slight sedation. Medetomidine induced moderate or deep sedation, and all dogs were deeply sedated after administration of medetomidine/l–methadone. Reaction to a noxious stimulus was strong or moderate after administration of methadone, moderate or absent after administration of medetomidine, and absent after administration of medetomidine/l–methadone.Conclusions and clinical relevanceAt the doses used in this study, l–methadone potentiated the sedative and analgesic effects and the decrease in arterial oxygenation induced by medetomidine in dogs, which limits the clinical use of this combination.     

Clinicophysiological Effects of Spinally Administered Ketamine and Its Combination with Xylazine and Medetomidine in Healthy Goats

The study was conducted in 9 healthy adult goats of either sex, weighing 15–20 kg, to evaluate and compare the clinicophysiological effects of spinally administered ketamine alone and in combination with xylazine and medetomidine. Nine trials each of the three treatments were conducted randomly by injecting ketamine (2.5 mg/kg) (n = 9), ketamine and xylazine (2.5 mg/kg and 0.05 mg/kg) (n = 9) and ketamine and medetomidine (2.5 mg/kg and 10 μg/kg) (n = 9). The drugs were administered at the lumbosacral subarachnoid space under strict aseptic conditions. The treatments were evaluated on the basis of clinicophysiological, haematological, biochemical and haemodynamic observations. Ketamine produced mild to moderate analgesia of the hindquarters. Its combination with either xylazine or medetomidine produced complete analgesia of the hindquarters for 45–60 min. Ataxia was moderate in the ketamine group, whereas animals attained sternal recumbency in the combination groups. A moderate degree of sedation was recorded in the combination groups. Heart rate and respiratory rate depression in the combination groups and heart rate and respiratory rate stimulation in ketamine group were recorded. Haematological parameters decreased in all the groups. Increase in serum glucose, creatinine and urea nitrogen was recorded in all the groups. Serum electrolytes did not show any significant change. The results showed that the combination of ketamine with xylazine or medetomidine at these dose rates produced a comparable degrees of analgesia of hindquarters with transient and minimal cardiopulmonary side effects.     

A comparison of the efficacy and cardiorespiratory effects of four medetomidine-based anaesthetic protocols in the red fox (Vulpes vulpes)

ObjectiveTo evaluate the anaesthetic and cardiorespiratory effects of four anaesthetic protocols in red foxes (Vulpes vulpes).Study designProspective, blinded and randomized complete block design.AnimalsTen adult captive red foxes.MethodsFoxes were anaesthetized by intramuscular (IM) injection using four protocols in random order: medetomidine 40 μg kg^?1, midazolam 0.3 mg kg^?1 and butorphanol 0.1 mg kg^?1 (MMiB), medetomidine 40 μg kg^?1 and ketamine 4 mg kg^?1 (MK40/4), medetomidine 60 μg kg^?1 and ketamine 4 mg kg^?1 (MK60/4), medetomidine 40 μg kg^?1 and tiletamine/zolazepam 2 mg kg^?1 (MTZ). Time to lateral recumbency, induction time and time to recovery following IM administration of atipamezole 0.2 mg kg^?1 were recorded. Heart rate (HR), respiratory rate (_fR) and rhythm, blood pressure, rectal temperature, end-tidal CO₂ tension (Pe′Co₂), functional oxygen saturation and presence/absence of interdigital, palpebral and ear reflexes were recorded every 10 minutes, and following administration of atipamezole. Data were analysed using two-way repeated-measures anova with Bonferroni post tests; p < 0.05 was considered significant.ResultsAll protocols produced profound sedation with good muscle relaxation. Only the MMiB protocol diverged significantly from the others. Induction of anaesthesia and recovery time following atipamezole were significantly longer, and f_R and initial HR significantly lower with MMiB than with the other protocols. With all protocols, mean arterial blood pressure (MAP) was initially relatively high (140–156 mmHg), and decreased significantly over time. With all protocols, the administration of atipamezole resulted in a rapid, significant decrease in MAP and an increase in HR.Conclusions and clinical relevanceAll four protocols provided anaesthetic conditions suitable for minor procedures and allowed endotracheal intubation. The cyclohexanone protocols provided quicker and more reliable inductions and recoveries than the MMiB protocol.     

Anesthetic effects of ketamine–medetomidine–hydromorphone in dogs during high-quality,high-volume surgical sterilization program under field conditions

ObjectiveTo describe the anesthetic and adverse effects of an injectable anesthetic protocol in dogs as part of a high-volume sterilization program under field conditions in Belize.Study designProspective, observational, field study.AnimalsA total of 23 female and eight male dogs (14.2 ± 7.7 kg; age ≥ 8 weeks).MethodsUsing a volume per kg-based dose chart, dogs were administered ketamine (4.5 mg kg⁻¹), medetomidine (0.04 mg kg⁻¹) and hydromorphone (0.09 mg kg⁻¹) intramuscularly. After induction of anesthesia, an endotracheal tube was inserted and dogs were allowed spontaneous breathing in room air. Monitoring included peripheral oxygen saturation (SpO₂), mean arterial pressure (MAP), heart rate (HR), respiratory rate, rectal temperature and end-tidal carbon dioxide (Pe′CO₂). Meloxicam (0.2 mg kg⁻¹) was administered subcutaneously after surgery. Data were analyzed with linear models and chi-square tests (p < 0.05).ResultsOnset of lateral recumbency (3.4 ± 2 minutes) was rapid. Desaturation (SpO₂ < 90%) was observed at least once in 64.5% of dogs and was more frequent in large dogs (p = 0.019). Hypercapnia (Pe′CO₂ ≥ 50 mmHg; 6.7 kPa) was observed in 48.4% of dogs. MAP was 111 ± 19 mmHg, mean ± standard deviation. Hypertension (MAP ≥ 120 mmHg), bradycardia (HR ≤ 60 beats minute⁻¹) and tachycardia (HR ≥ 140 beats minute⁻¹) were observed in 45.2%, 16.1% and 3.3% of dogs, respectively. Hypotension and hypothermia were not observed. Sex was not significantly associated with any complication. Return of swallowing reflex and time to standing were 71 ± 23 and 152 ± 50 minutes after injection, respectively. Return of swallowing was significantly longer in large dogs.Conclusions and clinical relevanceAt the doses used, ketamine–medetomidine–hydromorphone was effective in dogs for high-volume sterilization. In this field setting, adverse effects included hypoventilation, hypoxemia and prolonged recovery.     

Comparison of the effects of butorphanol–midazolam–medetomidine and butorphanol–azaperone–medetomidine in wild common palm civets (Paradoxurus musangus)

ObjectiveTo assess the efficacy of butorphanol–azaperone–medetomidine (BAM) and butorphanol–midazolam–medetomidine (BMM) protocols for immobilization of wild common palm civets (Paradoxurus musangus) with subsequent antagonization with atipamezole.Study designProspective, randomized, blinded clinical trial.AnimalsA total of 40 adult wild common palm civets, 24 female and 16 male, weighing 1.5–3.4 kg.MethodsThe civets were randomly assigned for anesthesia with butorphanol, azaperone and medetomidine (0.6, 0.6 and 0.2 mg kg^–1, respectively; group BAM) or with butorphanol, midazolam and medetomidine (0.3, 0.4 and 0.1 mg kg^–1, respectively; group BMM) intramuscularly (IM) in a squeeze cage. When adequately relaxed, the trachea was intubated for oxygen administration. Physiological variables were recorded every 5 minutes after intubation. Following morphometric measurements, sampling, microchipping and parasite treatment, medetomidine was reversed with atipamezole at 1.0 or 0.5 mg kg^–1 IM to groups BAM and BMM, respectively. Physiological variables and times to reach the different stages of anesthesia were compared between groups.ResultsOnset time of sedation and recumbency was similar in both groups; time to achieve complete relaxation and tracheal intubation was longer in group BAM. Supplementation with isoflurane was required to enable intubation in five civets in group BAM and one civet in group BMM. All civets in group BAM required topical lidocaine to facilitate intubation. End-tidal carbon dioxide partial pressure was lower in group BAM, but heart rate, respiratory rate, rectal temperature, peripheral hemoglobin oxygen saturation and mean arterial blood pressure were not different. All civets in both groups recovered well following administration of atipamezole.Conclusions and clinical relevanceBoth BAM and BMM combinations were effective for immobilizing wild common palm civets. The BMM combination had the advantage of producing complete relaxation that allowed intubation more rapidly.