Evaluation of anesthetic, analgesic, and cardiorespiratory effects in dogs after intramuscular administration of dexmedetomidine-butorphanol-tiletamine-zolazepam or dexmedetomidine-tramadol-ketamine drug combinations

Ketamine-Propofol Coadministration for Induction and Infusion Maintenance in Anesthetized Dogs: Effects on Electroencephalography and Antinociception

The effects of concurrent ketamine and propofol (ketofol) constant rate infusion (CRI) were examined in six dogs. The K:P ratio was 1:2, with an initial CRI of 0.25/0.5 mg/kg/min over ten minutes, followed by a 0.5 mg/kg ketamine bolus for induction. During induction, a comprehensive EEG frequency spectrum from delta to gamma was observed, accompanied by subanesthetic-dose ketofol-induced behavioral excitation, including nystagmus, tongue flicking, salivation and active muscle activity. The dogs were maintained on three 15 min decremental doses of ketofol CRI (0.8/1.6, 0.4/0.8 and 0.2/0.4 mg/kg/min). This phase featured a significant decrease in the Patient State Index, electromyographic activity and a shift to low beta waves (SEF95: 13-18 Hz). Additionally, profound antinociception to electric stimulation and a stable heart rate and blood pressure (MBP 81.5-110 mmHg) were observed, as well as a merging of ketamine and propofol EEG characteristics during maintenance. In the recovery phase, a return to beta and gamma EEG patterns and excitement behavior occurred, accompanied by a significant reduction in antinociception, highlighting features of low doses of ketofol. This study reveals biphasic EEG dynamic changes, associated behaviors and robust antinociception and cardiovascular function, suggesting the utility of ketofol as a total intravenous anesthetic combination in dogs.

Electroencephalographic and Cardiovascular Changes Associated with Propofol Constant Rate of Infusion Anesthesia in Young Healthy Dogs

This study aimed to evaluate electroencephalography (EEG) and cardiovascular changes associated with propofol constant rate of infusion (CRI) anesthesia in dogs. Six dogs were each given propofol CRI to induce different anesthetic phases including induction (1 mg/kg/min for 10 min), and decremental maintenance doses of 2.4 mg per kg per min, 1.6 mg per kg per min, and 0.8 mg per kg per minute over 45 min. Processed EEG indices including patient state index (PSI), (burst) suppression ratio (SR), and spectral edge frequency (95%) were obtained continuously until the dogs recovered to sternal recumbency. The dogs were intubated and ventilated. Cardiovascular and EEG index values were compared between anesthetic phases. The PSI, SR, mean arterial blood pressure, and subjective anesthetic depth scores were highly correlated throughout anesthetic depth changes. The PSI decreased from 85.0 ± 17.3 at awake to 66.0 ± 29.0 at induction, and then sharply reduced to 19.7 ± 23.6 during maintenance and returned to 61.5 ± 19.2 at extubation. The SR increased from 15.4 ± 30.9% at induction to 70.9 ± 39.8% during maintenance and decreased to 3.4 ± 8.9% at extubation. We concluded that EEG indices can be used to aid in tracking ongoing brain state changes during propofol anesthesia in dogs.

Intraocular pressure and cardiovascular effects of dexmedetomidine premedication and tiletamine-zolazepam for anesthetic induction in dogs

Background and Aim

The effect of anesthetic drugs on intraocular pressure (IOP) is an important concern in ophthalmic surgery. The impact of dexmedetomidine (DEX) combined with tiletamine-zolazepam on IOP is scarcely studied. This study aimed to evaluate IOP and cardiovascular effects in dogs after premedication with 5 μg/kg (DEX5) or 10 μg/kg (DEX10) of intramuscular DEX followed by intravenous tiletamine-zolazepam administration for induction of anesthesia in healthy dogs.

Materials and Methods

Eighteen dogs, American Society of Anesthesiologists I or II, without ocular abnormality were investigated. All dogs were randomly divided into the DEX5 (n = 9) and DEX10 groups (n = 9). The IOP, heart rate (HR), systolic blood pressure (SBP), oxygen saturation, and sedation scale were measured before premedication (baseline), after premedication at 5, 10, 15, and 20 min, after tiletamine-zolazepam administration, after endotracheal intubation, and post-operative.

Results

There were no significant differences between the groups at any time point. The DEX5 and DEX10 groups had significantly decreased HR values at 10 min compared with baseline. The IOP at 20 min was significantly lower compared to the baseline in the DEX10 group. Moreover, the DEX10 group showed increased IOP, HR, SBP, and sedation scale values after induction and intubation compared with 20 min, but these values did not differ significantly from baseline. All parameters of both groups did not change significantly between post-operative and baseline.

Conclusion

Intramuscular DEX (10 μg/kg) is an appropriate premedication in ophthalmic examination or surgical procedures. Moreover, it could be combined with tiletamine-zolazepam for generalized anesthesia in dogs with an ophthalmic problem, as it had no clinically significant effects on IOP or cardiovascular values.

Cardiopulmonary (No Ventilation) and Anesthetic Effects of Dexmedetomidine-Tiletamine in Dogs

The aim of the present study was to evaluate the anesthetic and cardiopulmonary effects of dexmedetomidine in combination with tiletamine (without zolazepam) as a general anesthetic. The study was divided into two phases. In Phase 1, 18 adult healthy mixed-breed dogs were randomly allocated into three groups: Group TD8 (4.5 mg kg⁻¹ tiletamine and 8 μg kg⁻¹ dexmedetomidine), Group TD10 (4.5 mg kg⁻¹ tiletamine and 10 μg kg⁻¹ dexmedetomidine), or Group TD12 (4.5 mg kg⁻¹ tiletamine and 12 μg kg⁻¹ dexmedetomidine). After drug administration, the heart rate (HR), respiratory rate (f_R), mean arterial pressure (MAP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), peripheral hemoglobin oxygen saturation (SpO₂), behavioral score, quality of induction and recovery, extent of ataxia, the time taken for induction, and the duration of anesthesia were recorded. The recovery time and quality were recorded after administration of atipamezole (50 μg kg⁻¹) after 60 min. In phase 2, the feasibility of combining dexmedetomidine (10 μg kg⁻¹) and tiletamine (4.5 mg kg⁻¹) as general anesthetics for orchiectomy was evaluated in dogs (n = 6). HR, f_R, MAP, SAP, DAP, temperature, SpO₂, behavioral scores, and adverse reactions were recorded during each surgical procedure. In phase 1, the dogs were anesthetized for 5 min after administration of drugs and achieved a maximum behavioral score in TD10 and TD12 after 10 min. Although HR, MAP, SAP, DAP, and NIBP decreased in all three groups, they still maintained within the normal range. In phase 2, orchiectomy was completed smoothly in all dogs with little fluctuation in the physiological variables. We found that a combination of tiletamine (4.5 mg kg⁻¹) and dexmedetomidine (10 μg kg⁻¹) intramuscularly induced moderate anesthesia in dogs and could be utilized for short-term anesthesia and minor surgery.

Sedative and analgesic effects of two subanaesthetic doses of ketamine in combination with methadone and a low dose of dexmedetomidine in healthy dogs

OBJECTIVE

To evaluate the sedative, analgesic and recovery characteristics of two subanaesthetic ketamine doses in combination with dexmedetomidine and methadone for intramuscular sedation in healthy Beagles.

STUDY DESIGN

Randomized, blinded, crossover, experimental study.

ANIMALS

Six healthy adult Beagles.

METHODS

Dogs were randomly given three treatments: dexmedetomidine (3 μg kg^-1) and methadone (0.3 mg kg^-1) combined with ketamine at 1 and 2 mg kg^-1 (K1 and K2, respectively) or saline (K0), intramuscularly. Sedation score, response to tail clamping and rectal temperature were recorded at baseline, 5, 15, 25, 35, and 45 minutes posttreatment. Pulse rate (PR), respiratory rate, oxygen haemoglobin saturation and noninvasive blood pressure were also recorded at baseline and every 5 minutes until 45 minutes posttreatment. Onset and duration of recumbency, response to venous catheterization and recovery quality were also assessed. Sedation and physiological variables were compared between treatments and within treatments compared to baseline (analysis of variance). Nonparametric data were analysed with the Friedman and Cochran's Q tests; p < 0.050.

RESULTS

Increased sedation was found at 15 (K0 and K1), 25 (all treatments) and 35 (K1) minutes compared with baseline. Sedation score, onset (3-12 minutes) and duration of recumbency (29-51 minutes) were similar between treatments. Recovery quality was considered acceptable in all cases. Response to tail clamping was inconsistent within treatments with no differences between them. None of the dogs responded to venous catheterization. There were no differences between treatments in physiological variables, except for PR which was higher in K2 than in K0. Oxygen supplementation was required in five and three dogs administered saline and ketamine, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The addition of 1 or 2 mg kg^-1 of ketamine to methadone and dexmedetomidine combination did not enhance sedation or antinociception in healthy dogs. Recovery quality was unaffected.

Tiletamine/zolazepam and dexmedetomidine with tramadol provide effective general anesthesia in rats

Background

Tiletamine/zolazepam is a dissociative anesthetic combination commonly used in small animals but information is limited in rats. The alpha-2 agonist, dexmedetomidine, has gained popularity in laboratory animal anesthesia. Tramadol is a weak opioid mu agonist. The aim of this study was to assess whether the tiletamine/zolazepam/dexmedetomidine (ZD) combination effectively provides a surgical anesthesia plane comparable to tiletamine/zolazepam/dexmedetomidine with tramadol (ZDT) in a minor procedure in rats.

Methods

Rats were induced with ZD or ZDT. After the loss of paw withdrawal, a small incision was made on the rats' left thighs as a surgical stimulus. Rats were maintained under a surgical anesthesia plane by assessing the loss of the paw withdrawal reflex for 45 minutes, then atipamezole was administered. Monitored anesthesia parameters included: (a) physiological parameters - pulse rate (PR), respiratory rate (RR), tissue oxygen saturation (%SpO2), and body temperature; (b) duration parameters - induction time, onset and duration of surgical anesthesia plane, onset of recovery, and recovery time.

Results

PR was significantly lower at 10 minutes in ZD and 5 minutes in ZDT groups. No difference was observed for RR, %SpO2, and body temperature. Likewise, there were no differences for duration parameters: induction time was less than 3 minutes; onset and duration of surgical anesthesia plane were approximately 5 and 45 minutes, respectively; onset of recovery (time to move) was 51 minutes; and recovery time was 52 minutes, respectively.

Conclusion

These data suggest the ZD combination provides a surgical anesthesia plane comparable to ZDT in a rat incisional pain model.

Effects of dexmedetomidine on perioperative stress response, inflammation and immune function in patients with different degrees of liver cirrhosis

Effects of dexmedetomidine (DEX) on perioperative stress response, inflammation and immune function in patients with different degrees of liver cirrhosis were investigated. A total of 94 patients with liver cirrhosis who were admitted to the Affiliated Hospital of Shandong University of Traditional Chinese Medicine from December 2016 to November 2017 were included, and randomly divided into control and observation group (n=47). Patients in control group were given remifentanil for anesthesia, while patients in observation group were treated with remifentanil and for DEX anesthesia. Venous blood was collected immediately before induction of anesthesia (T1), 10 min (T2) after the beginning of surgery, immediately after surgery (T3) and 2 h after surgery (T4). Hemodynamic parameters, stress response factors, adverse reactions and levels of inflammatory cytokines and T lymphocyte subsets were compared between the two groups. The mean arterial pressure in both groups was lower at T2-T4 than that at T1 (p<0.05), and mean arterial pressure was lower in observation group than in control group (p<0.05). Visual analogue pain score (VAS) of observation group was significantly lower than that of control group at 6, 12 and 24 h after operation (p<0.05). There was no significant difference between the two groups in incidence of nausea, vomiting, hypoxemia and delayed awakening (p>0.05). Incidence of postoperative agitation in observation group was significantly lower than that in control group (p<0.05). The levels of CD3⁺, CD4⁺, and CD4⁺/CD8⁺ in both groups were significantly lower at T2-T4 than those at T1 (p<0.05). Levels of IL-10 and TNF-α in both groups were significantly higher at T2-T4 than those at T1, but levels of IL-2 and TNF-α were significantly lower in observation group than in control group (p<0.05). In conclusion, the use of DEX for anesthesia in patients with liver cirrhosis can improve hemodynamic stability, reduce stress response and reduce inflammation level without affecting immune function, which has important clinical significance.

The Association of Shelter Veterinarians' 2016 Veterinary Medical Care Guidelines for Spay-Neuter Programs

As community efforts to reduce the overpopulation and euthanasia of unwanted and unowned cats and dogs have increased, many veterinarians have increasingly focused their clinical efforts on the provision of spay-neuter services. Because of the wide range of geographic and demographic needs, a wide variety of spay-neuter programs have been developed to increase delivery of services to targeted populations of animals, including stationary and mobile clinics, MASH-style operations, shelter services, community cat programs, and services provided through private practitioners. In an effort to promote consistent, high-quality care across the broad range of these programs, the Association of Shelter Veterinarians convened a task force of veterinarians to develop veterinary medical care guidelines for spay-neuter programs. These guidelines consist of recommendations for general patient care and clinical procedures, preoperative care, anesthetic management, surgical procedures, postoperative care, and operations management. They were based on current principles of anesthesiology, critical care medicine, infection control, and surgical practice, as determined from published evidence and expert opinion. They represent acceptable practices that are attainable in spay-neuter programs regardless of location, facility, or type of program. The Association of Shelter Veterinarians envisions that these guidelines will be used by the profession to maintain consistent veterinary medical care in all settings where spay-neuter services are provided and to promote these services as a means of reducing sheltering and euthanasia of cats and dogs.

Alfaxalone alone or combined with midazolam or ketamine in dogs: intubation dose and select physiologic effects

OBJECTIVE

To determine the intubation dose and select physiologic effects of alfaxalone alone or in combination with midazolam or ketamine in dogs.

STUDY DESIGN

Prospective, clinical study.

ANIMALS

Fifty-three healthy client-owned dogs [mean±standard deviation (SD)] 5.1±1.8 years, 27±15.4 kg, scheduled for elective orthopedic surgery.

METHODS

After premedication with acepromazine (0.02 mg kg^-1) and hydromorphone (0.1 mg kg^-1) intramuscularly, alfaxalone (0.25 mg kg^-1) was administered intravenously over 15 seconds followed immediately by 0.9% saline (AS), midazolam (0.3 mg kg^-1; AM), ketamine (1 mg kg^-1; AK1), or ketamine (2 mg kg^-1; AK2). Additional alfaxalone (0.25 mg kg^-1 increments) was administered as required to permit endotracheal intubation. The incidence of apnea and the time from intubation until spontaneous movement were recorded. Heart rate (HR) and blood pressure were recorded 15 minutes after premedication, after intubation and 2, 5, 10 and 15 minutes thereafter. Blood was collected for measurement of serum glucose and insulin concentrations before induction, after intubation and at 2, 5, 10 and 50 minutes. Data were analyzed by split-plot anova with Bonferroni adjustment for the number of group comparisons.

RESULTS

Mean±SD alfaxalone mg kg^-1 doses required for endotracheal intubation were AS (1.0±0.4), AM (0.4±0.2), AK1 (0.5±0.3) and AK2 (0.5±0.4) (p=0.0005). Differences in cardiopulmonary variables among groups were minor; HR decreased in AS, while in other groups, HR increased transiently postintubation. Incidence of apnea in AS was 54% with no significant difference among groups. Midazolam significantly prolonged time from intubation until spontaneous movement (p<0.002).

CONCLUSIONS AND CLINICAL RELEVANCE

Midazolam and ketamine reduced the alfaxalone dose required for endotracheal intubation. Serum glucose and insulin concentrations were not influenced by administration of alfaxalone alone or when administered with midazolam or ketamine.