Inadvertent Perianesthetic Hypothermia in Small Animal Patients

IMMOBILIZATION OF BLACK HOWLER MONKEYS (ALOUATTA PIGRA) USING BUTORPHANOL, AZAPERONE, MEDETOMIDINE IS SAFE AND EFFECTIVE FOR NONINVASIVE PROCEDURES

Administration of butorphanol, azaperone, and medetomidine (BAM) for immobilization of black howler monkeys (Alouatta pigra) has not been previously reported. In this observational study, 0.02 ml/kg of compounded BAM (butorphanol 27.3 mg/ml, azaperone 9.1 mg/ml, medetomidine 10.9 mg/ml) was administered IM in 10 captive black howler monkeys. Time to immobilization was recorded, an arterial blood gas performed, and at 5-min intervals, HR, RR, oscillometric arterial blood pressure, SPO2, and rectal temperature were measured. Naltrexone and atipamezole were administered IM at procedure completion and recovery times were recorded. If invasive procedures such as surgery were necessary and additional drugs needed, further data from that individual was removed from data analysis. Final BAM dosages were 0.55 ± 0.12 mg/kg butorphanol, 0.19 ± 0.04 mg/kg azaperone, and 0.22 ± 0.05 mg/kg medetomidine. Nine of 10 monkeys achieved sedation allowing for physical exam, venipuncture, and tuberculin skin testing within 4 ± 2 min. No monkeys reached a plane of immobilization allowing for intubation. Physiologic variables were acceptable for this species. Hypoxemia (SPO2 < 95%) was observed in three monkeys via pulse oximetry, and normoxemia was observed on arterial blood gas. Recovery was smooth and rapid. Therefore, BAM is a viable option for noninvasive procedures or as a premedication prior to induction of anesthesia in black howler monkeys.

Association between body mass and hypotension in dogs under general anaesthesia

OBJECTIVES

To investigate the association between body mass and hypotension during general anaesthesia in dogs undergoing surgical and diagnostic procedures within a referral hospital.

MATERIALS AND METHODS

Retrospective evaluation of the anaesthetic records of 1789 dogs was performed. Data on signalment, anaesthetic protocol and physiological variables, including mean arterial pressure, were collected. A multivariable generalised linear model was used to identify associations between explanatory variables, including body mass, and hypotension.

RESULTS

In the population studied, increasing body mass (per 10 kg) was significantly associated with decreasing odds of hypotension (odds ratio 0.68; 95% confidence interval: 0.60 to 0.77). Additional variables associated with a decreased odds of hypotension were pre-anaesthetic medication with alpha-2 agonists (odds ratio 0.63; 95% confidence interval 0.48 to 0.82) and increased body temperature (per 1°C) during general anaesthesia (odds ratio 0.77; 95% confidence interval 0.67 to 0.88). Brachycephaly (odds ratio 1.72; 95% confidence interval 1.25 to 2.38), ASA physical status classification >3 (odds ratio 2.03; 95% confidence interval 1.16 to 3.56), undergoing a surgical procedure (versus diagnostic) (odds ratio 1.57; 95% confidence interval 1.10 to 2.23) and bradycardia (odds ratio 1.37; 95% confidence interval 1.05 to 1.80) were independently associated with increased odds of hypotension.

CLINICAL SIGNIFICANCE

Dogs of lower body mass and brachycephalic breeds may be at higher risk of hypotension during general anaesthesia or alternatively represent subpopulations in which accurate blood pressure measurement presents a greater challenge. Monitoring blood pressure accurately in these groups requires particular attention and provisions for treating hypotension should be readily accessible.

Retrospective investigation of decreasing body temperature trends during anaesthesia in dogs

BACKGROUND

Hypothermia during the perianaesthetic period may lead to an increased risk of morbidity in veterinary patients. However, the timeline of the decrease in body temperature during general anaesthesia has been minimally investigated.

METHODS

Anaesthetic records of 1097 client-owned dogs were examined. Change in body temperature (ΔBT = baseline temperature - time point temperature) was plotted over time for all dogs. The slope of ΔBT was calculated for each 15-minute interval, and the magnitude of the largest ΔBT and the time point at which the largest ΔBT occurred were determined for each record.

RESULTS

A rapid decline in ΔBT occurred from 0 to 15 minutes, a slower decline occurred from 15 to 60 minutes and a plateau occurred from 60 to 240 minutes. The largest ΔBT occurred at 75 (15-240) minutes from baseline, with a maximum ΔBT of -2.06°C (-0.06°C to -8.72°C).

LIMITATIONS

This is a retrospective study. As such, there were missing data points and potential confounding factors could not be controlled for.

CONCLUSIONS

Anaesthetised dogs exhibited a distinct pattern of decrease in body temperature, with the most rapid reduction occurring within the first 15 minutes. The effects of procedures and anaesthetic agents on the timeline and pattern of heat loss warrant further investigation.

Temperature Monitoring and Thermal Support in Exotic Animal Critical Care

Body temperature measurement is one of the most important parameters to assess the health of a patient. In small exotic mammals, rectal temperature is obtained via a similar process as in dogs or cats, with a few specific differences. In reptiles and birds, measurement of body temperature can provide important information, albeit its accuracy may be limited. In most animals, temperature should be taken at the beginning of the examination to not artificially elevate the temperature during the physical exam. Heat support is typically indicated any time a patient's temperature is below the accepted core temperature range and cooling may be indicated whenever a patient's temperature exceeds a critical point.

Effects of peripheral active warming and passive insulation on core body temperature during feline ovariohysterectomy: a multi-arm randomized clinical trial

OBJECTIVES

Hypothermia is a common complication of anesthesia, particularly in cats. Some veterinarians insulate the extremities of cats as a preventive measure, and there is evidence that heating the extremities of dogs decreases the rate of heat loss from the core. This study investigated whether active warming or passive insulation of the extremities of cats resulted in a slower decrease in rectal temperature during anesthesia.

METHODS

Female cats were assigned via block randomization to passive (cotton toddler socks), active (heated toddler socks) or control group (uncovered extremities). Rectal temperature was monitored every 5 mins from induction through return to trap/carrier (final temperature). Multivariable linear regression models were used to compare temperature (rate change and final) between groups.

RESULTS

There were 164 cats with 1757 temperature readings. Mean total duration of anesthesia was 53 ± 13 mins. The temperature of all groups decreased linearly over time (all P <0.0001), with the rates of temperature decrease being -0.039°F/min (95% confidence interval [CI] -0.043 to -0.035)/-0.022°C (95% CI -0.024 to -0.019), -0.039°F/min (95% CI -0.042 to -0.035)/-0.022°C (95% CI -0.023 to -0.019) and -0.029°F/min (95% CI -0.032 to -0.025)/-0.016°C (95% CI -0.018 to -0.014) for the control, passive and active groups, respectively. The control, passive and active groups had median final temperatures of 98.4°F (interquartile range [IQR] 97.6-99.4)/36.9°C (IQR 36.4-37.4), 98.0°F (IQR 97.2-98.7)/36.7°C (IQR 36.2-37.1) and 99.1°F (IQR 97.7-100.0)/37.3°C (IQR 36.5-37.8), respectively. After controlling for weight, postinduction temperature and duration of anesthesia, and as compared with controls, the final temperature of the active group was predicted to be 0.54°F (95% CI 0.03-1.01)/0.3°C (95% CI 0.02-0.56) greater (P = 0.023), while the passive group was not significantly different (P = 0.130).

CONCLUSIONS AND RELEVANCE

The rate of rectal temperature decrease was significantly slower for the active group compared with the other groups. Although the cumulative difference in final temperature reading was modest, superior materials might enhance performance. Cotton toddler socks alone did not slow the rate of temperature decrease.

Clinicoepidemiological profile and risk factors associated with mortality in traumatized cats admitted to a veterinary teaching hospital in Brazil

OBJECTIVES

The aim of this study was to evaluate possible risk factors for death in traumatized cats based on the clinicoepidemiological profile, the Animal Trauma Triage (ATT) scale score and the Modified Glasgow Coma Scale (MGCS) score at the time of presentation to the hospital.

METHODS

This was a cross-sectional study involving cats admitted to the emergency sector (ES) and the surgical clinic sector (SCS) of a veterinary teaching hospital (VTH) in northeastern Brazil over a 12-month period (2018-2019). Probable risk factors associated with non-survival after trauma were analyzed by calculating the prevalence ratio. The prediction of non-survival was evaluated by analyzing the receiver operating characteristic (ROC) curve employing the ATT scale score, MGCS score and rectal temperature.

RESULTS

In 1 year, 89 traumatized cats were admitted to the VTH, of which 90% (n = 80) were young, 54% (n = 48) were male, 79% (n = 70) were intact, 59% (n = 53) were indoor cats and 92% (n = 82) were considered as mixed breed. Blunt trauma was the most prevalent cause of injuries, reported in 76% (n = 68) of the cats. Accidents involving falls (30%; n = 27) that affected the pelvic limbs (50.6%) were the most commonly reported. The prevalence of death among cats admitted to the ES was 9.44 times higher than that of animals treated at the SCS. Trauma as result of being run over and chest trauma were associated with a higher probability of death. Most of the animals that died had a lower rectal temperature than those that survived. The ATT scale score, MGCS score and rectal temperature were predictive of mortality.

CONCLUSIONS AND RELEVANCE

Rectal temperature, ATT scale score and MGCS score were effective predictors of an unfavorable prognosis and point to the need for emergency procedures. Hypothermia, being run over and chest trauma were associated with a higher risk of mortality. Our findings highlight the importance of prompt and effective care for these conditions.

Effects of a Heated Anesthesia Breathing Circuit on Body Temperature in Anesthetized Rhesus Macaques (Macaca mulatta)

This study evaluated the effects of using a heated anesthesia breathing circuit in addition to forced-air warming on body temperature in anesthetized rhesus macaques as compared with forced-air warming alone. Hypothermia is a common perianesthetic and intraoperative complication that can increase the risk of negative outcomes. Body heat is lost through 4 mechanisms during anesthesia: radiation, conduction, convection, and evaporation. Typical warming methods such as forced-air warming devices, conductive heating pads, and heated surgical tables only influence radiative and conductive mechanisms of heat loss. A commercially available heated breathing circuit that delivers gas warmed to 104 °F can easily be integrated into an anesthesia machine. We hypothesized that heating the inspired anesthetic gas to address the evaporative mechanism of heat loss would result in higher body temperature during anesthesia in rhesus macaques. Body temperatures were measured at 5-min intervals in a group of 10 adult male rhesus macaques during 2 anesthetic events: one with a heated anesthesia breathing circuit in addition to forced-air warming, and one with forced-air warming alone. The addition of a heated breathing circuit had a significant positive effect on perianesthetic body temperature, with a faster return to baseline temperature, earlier nadir of initial drop in body temperature, and higher body temperatures during a 2-h anesthetic procedure. Use of a heated anesthesia breathing circuit should be considered as a significant refinement to thermal support during macaque anesthesia, especially for procedures lasting longer than one hour.

Multicenter study to investigate factors associated with change in rectal temperature during anesthesia in dogs

OBJECTIVE

To determine factors associated with change in rectal temperature (RT) of dogs undergoing anesthesia.

ANIMALS

507 dogs.

PROCEDURES

In a prospective observational study, the RT of dogs undergoing anesthesia at 5 veterinary hospitals was recorded at the time of induction of anesthesia and at the time of recovery from anesthesia (ie, at the time of extubation). Demographic data, body condition score, American Society of Anesthesiologists (ASA) physical status classification, types of procedure performed and medications administered, duration of anesthesia, and use of heat support were also recorded. Multiple regression analysis was performed to determine factors that were significantly associated with a decrease or an increase (or no change) in RT. Odds ratios were calculated for factors significantly associated with a decrease in RT.

RESULTS

Among the 507 dogs undergoing anesthesia, RT decreased in 89% (median decrease, -1.2°C [-2.2°F]; range, -0.1°C to -5.7°C [-0.2°F to -10.3°F]), increased in 9% (median increase, 0.65°C [1.2°F]; range, 0.1°C to 2.1°C [3.8°F]), and did not change in 2%. Factors that significantly predicted and increased the odds of a decrease in RT included lower weight, ASA classification > 2, surgery for orthopedic or neurologic disease, MRI procedures, use of an α₂-adrenergic or μ-opioid receptor agonist, longer duration of anesthesia, and higher heat loss rate. Lack of μ-opioid receptor agonist use, shorter duration of anesthesia, and lower heat loss rate were significantly associated with an increase in RT.

CONCLUSIONS AND CLINICAL RELEVANCE

Multiple factors that were associated with a decrease in RT in dogs undergoing anesthesia were identified. Knowledge of these factors may help identify dogs at greater risk of developing inadvertent perianesthetic hypothermia.

Evaluation of tumescent local anesthesia in cats undergoing unilateral mastectomy

OBJECTIVE

To evaluate the analgesic efficacy and safety of tumescent local anesthesia (TLA) in cats undergoing unilateral mastectomy.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

A total of 12 ovariohysterectomized female cats.

METHODS

All animals were premedicated with pethidine (4 mg kg^-1) intramuscularly (IM), followed by induction of anesthesia with propofol (5 mg kg^-1) intravenously and maintenance with isoflurane in oxygen. A refrigerated TLA solution (15 mL kg^-1, 8 °C) was injected using a Klein cannula. The solution was composed of 0.5 mL of epinephrine (1 mg mL^-1) and 40 mL of 2% lidocaine added to 210 mL lactated Ringer's solution (final lidocaine concentration 0.32%). Heart and respiratory rates, systolic arterial blood pressure, temperature and oxygen saturation were measured during anesthesia. Blood samples were collected from the jugular vein for measurement of plasma lidocaine concentration using high performance liquid chromatography. Postoperative pain scores were evaluated hourly for 6 hours. Analgesic rescue was performed with tramadol (2 mg kg^-1) IM and meloxicam (0.15 mg kg^-1) subcutaneously.

RESULTS

Plasma lidocaine concentration peaked at 90 minutes after injection of TLA, but no concentration considered toxic for the species was measured. The median postoperative analgesia time was 6 hours after injection of TLA.

CONCLUSIONS

This study found that TLA prevented sympathetic response to noxious stimuli during anesthesia and provided satisfactory postoperative analgesia in cats submitted to total unilateral mastectomy, with no apparent signs of toxicity.

CLINICAL RELEVANCE

TLA can prevent sympathetic stimulation resulting from noxious stimuli during anesthesia, promoting good intraoperative conditions, proving to be a viable addition to analgesia in cats submitted to a total unilateral mastectomy.

Evaluation of nalbuphine, butorphanol and morphine in dogs during ovariohysterectomy and on early postoperative pain

OBJECTIVE

To evaluate the effects of nalbuphine, butorphanol and morphine combined with acepromazine on intraoperative and early postoperative pain management in dogs anesthetized for ovariohysterectomy.

STUDY DESIGN

Prospective, randomized blinded clinical study.

ANIMALS

A total of 48 healthy female dogs of different breeds, aged 1-6 years, weighing (mean ± standard deviation) 14.5 ± 4.8 kg.

METHODS

Dogs were randomly assigned into four groups to be intravenously administered nalbuphine (0.5 mg kg^-1; group N0.5), nalbuphine (1.0 mg kg^-1; group N1.0), butorphanol (0.4 mg kg^-1; group B0.4) or morphine (0.2 mg kg^-1; group M0.2) combined with acepromazine (0.02 mg kg^-1) prior to propofol and isoflurane for anesthesia. Heart rate (HR), respiratory rate, systolic arterial pressure and rectal temperature (RT) were recorded at time points during anesthesia. A dynamic interactive visual analog scale applied in three phases (DIVAS I, II and III) and the modified Glasgow composite measure pain scale were used to assess pain before premedication and 1, 2, 3, 4, 5 and 6 hours after extubation. Administration of rescue analgesia was recorded.

RESULTS

At the left ovarian pedicle ligation, HR was higher in N1.0 than in B0.4 (p = 0.020). RT decreased significantly by the end of surgery in N0.5 (p = 0.043) and B0.4 (p = 0.010). Rescue analgesia was administered postoperatively over 6 hours to eight, seven, nine and 10 dogs in N0.5, N1.0, B0.4 and M0.2, respectively (p = 0.57). DIVAS II was higher in B0.4 than in N1.0 at 2 and 3 hours (p = 0.038 and p = 0.002, respectively) and N0.5 at 3 hours (p = 0.003).

CONCLUSIONS AND CLINICAL RELEVANCE

At the doses used, all premedication protocols provided insufficient intraoperative analgesia, with minimal clinical differences between groups. No premedication provided satisfactory analgesia in the first 6 hours postoperatively.

Cardiovascular effects of increasing dosages of norepinephrine in healthy isoflurane-anesthetized New Zealand White rabbits

OBJECTIVE

To characterize the cardiovascular effects of increasing dosages of norepinephrine (NE) in healthy isoflurane-anesthetized rabbits.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A total of nine female ovariohysterectomized New Zealand White rabbits weighing 3.4 ± 0.2 kg (mean ± standard deviation).

METHODS

Rabbits were premedicated intramuscularly with buprenorphine (0.05 mg kg^-1) and midazolam (0.5 mg kg^-1). Anesthesia was induced with intravenous propofol and maintained with a 1.1 × minimum alveolar concentration of isoflurane for this species to induce hypotension. Rabbits were administered NE infusions at three doses: low, 0.1 μg kg^-1 minute^-1; medium, 0.5 μg kg^-1 minute^-1; and high doses, 1 μg kg^-1 minute^-1 for 10 minutes each in that order. Cardiovascular variables including heart rate (HR), cardiac output (CO) by lithium dilution technique and systolic (SAP), mean (MAP) and diastolic (DAP) invasive arterial blood pressures measured in the auricular artery were recorded at baseline, 10 minutes after the start of the infusion of each NE treatment and 10 minutes after NE was discontinued. A linear mixed model and a type III anova with Tukey's post hoc comparison was performed (p < 0.05).

RESULTS

Significant increases in SAP (28% and 90%), MAP (27% and 90%) and DAP (33% and 97%) were measured with medium and high dose treatments, respectively (p < 0.001), with no changes in CO. HR decreased and stroke volume increased significantly with high dose treatment (by 17% and 15%, respectively; p < 0.05). No arrhythmias were noticed with NE treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

The infusion of NE at 0.5-1.0 μg kg^-1 minute^-1 is a potentially effective treatment for hypotension in healthy isoflurane-anesthetized New Zealand White rabbits.

Pneumoperitoneum in Veterinary Laparoscopy: A Review

Objective: To review the effects of carbon dioxide pneumoperitoneum during laparoscopy, evaluate alternative techniques to establishing a working space and compare this to current recommendations in veterinary surgery. Study Design: Literature review. Sample Population: 92 peer-reviewed articles. Methods: An electronic database search identified human and veterinary literature on the effects of pneumoperitoneum (carbon dioxide insufflation for laparoscopy) and alternatives with a focus on adaptation to the veterinary field. Results: Laparoscopy is the preferred surgical approach for many human and several veterinary procedures due to the lower morbidity associated with minimally invasive surgery, compared to laparotomy. The establishment of a pneumoperitoneum with a gas most commonly facilitates a working space. Carbon dioxide is the preferred gas for insufflation as it is inert, inexpensive, noncombustible, colorless, excreted by the lungs and highly soluble in water. Detrimental side effects such as acidosis, hypercapnia, reduction in cardiac output, decreased pulmonary compliance, hypothermia and post-operative pain have been associated with a pneumoperitoneum established with CO2 insufflation. As such alternatives have been suggested such as helium, nitrous oxide, warmed and humidified carbon dioxide and gasless laparoscopy. None of these alternatives have found a consistent benefit over standard carbon dioxide insufflation. Conclusions: The physiologic alterations seen with CO2 insufflation at the current recommended intra-abdominal pressures are mild and of transient duration. Clinical Significance: The current recommendations in veterinary laparoscopy for a pneumoperitoneum using carbon dioxide appear to be safe and effective.

Pre-warming before general anesthesia with isoflurane delays the onset of hypothermia in rats

General anesthesia causes hypothermia by impairing normal thermoregulatory mechanisms. When using inhalational anesthetic agents, Redistribution of warm blood from the core to the periphery is the primary mechanism in the development of hypothermia and begins following induction of anesthesia. Raising skin temperature before anesthesia reduces the temperature gradient between core and periphery, decreasing the transfer of heat. This prospective, crossover study (n = 17 adult male and female SD rats) compared three treatment groups: PW1% (pre-warming to increase core temperature 1% over baseline), PW40 (pre-warming to increase core temperature to 40°C) and NW (no warming). The PW1% group was completed first to ensure tolerance of pre-warming. Treatment order was then randomized and alternated after a washout period. Once target temperature was achieved, anesthesia was induced and maintained with isoflurane in oxygen without further external temperature support. Pre-warming was effective at delaying the onset of hypothermia, with a significant difference between PW1% (12.4 minutes) and PW40 (19.3 minutes, p = 0.0044 (95%CI -12 to -2.2), PW40 and NW (7.1 minutes, p < 0.0001 (95%CI 8.1 to 16.0) and PW1% and NW (p = 0.003, 95%CI 1.8 to 8.7). The rate of heat loss in the pre-warmed groups exceed that of the NW group: PW1% versus NW (p = 0.005, 95%CI 0.004 to 0.027), PW40 versus NW (p < 0.0001, 95%CI 0.014 to 0.036) and PW1% versus PW40 (p = 0.07, 95%CI -0.021 to 0.00066). Pre-warming alone confers a protective effect against hypothermia during volatile anesthesia; however, longer duration procedures would require additional heating support.

Intraoperative anaesthetic complications in dogs undergoing general anaesthesia for thoracolumbar hemilaminectomy: a retrospective analysis

OBJECTIVE

To establish the incidence of intraoperative anaesthetic complications in dogs undergoing general anaesthesia (GA) for thoracolumbar hemilaminectomy (TH), to determine whether GA duration affects incidence of intraoperative complications and to identify associations between intraoperative complications.

STUDY DESIGN

Retrospective observational study.

ANIMALS

A total of 224 client-owned dogs of various breeds undergoing TH for intervertebral disc extrusion.

METHODS

Anaesthetic records of dogs undergoing TH at a university teaching hospital between 2010 and 2016 were analysed. Data recorded included breed, sex, body weight, GA duration, magnetic resonance imaging (MRI) under the same GA, pharmacological intervention to increase heart rate (PIHR), hypotension (mean arterial blood pressure < 60 mmHg for ≥ 10 minutes), mechanical ventilation (MV) for inadequate ventilation, hypothermia (oesophageal temperature < 37 °C), oesophageal temperature ≥ 39 °C (T ≥ 39 °C), temperature trend, regurgitation and use of alpha-2 adrenoreceptor agonists, acepromazine, ketamine or lidocaine. Multivariate logistic regression models were fitted for hypothermia, T ≥ 39 °C, hypotension and PIHR with forced inclusion of GA duration.

RESULTS

Hypothermia was the most common complication (63.8% incidence), followed by MV implementation (63.4%), hypotension (33.9%), PIHR (24.6%), T ≥ 39 °C (20.5%) and regurgitation (4.9%). Multivariate models revealed that MRI and hypotension were associated with an increased risk of hypothermia, whilst increasing body weight, alpha-2 adrenoreceptor agonists and MV were associated with a reduced risk. Alpha-2 adrenoreceptor agonists and GA duration were associated with an increased risk of T ≥ 39 °C, whilst hypotension was associated with a reduced risk. Hypothermia and PIHR were associated with an increased risk of hypotension, whereas increased body weight was associated with a reduced risk. MV and hypothermia were associated with an increased risk of PIHR, whereas increased body weight was associated with a reduced risk.

CONCLUSIONS AND CLINICAL RELEVANCE

Increasing GA duration was associated with increased risk of T ≥ 39 °C, but not any other intraoperative complications.

Anaesthetic management and complications of canine adrenalectomies: 41 cases (2007-2017)

Little information is available about the management of adrenalectomies in veterinary anaesthesia. The aim of this study was to describe the anaesthetic techniques, the complication rate and outcome of these cases. Data were collected retrospectively from patients' records. Descriptive statistics were performed with Student's t-tests and Chi-square tests where appropriate. Forty-one cases were included. The mean age was 124.7 ± 29.4 months and the median body weight was 23.1 kg (5.3-69 kg). Carcinoma was the most common diagnosis (34.1%). Premedication was most commonly achieved with methadone alone (70.7%) IV. Propofol was the most common induction agent (39%). An infusion of opioids (80.4%) and an epidural injection of morphine (70.7%) were the most common analgesic techniques. Hypotension was the most common complication observed (51.2%). The mortality rate was 14.6%. The lowest recorded oesophageal temperature was statistically associated with the incidence of haemorrhage (P = 0.025). The invasion of the vena cava (P = 0.001) was significantly associated with haemorrhagic complications. The survival rate was better when patients received hydrocortisone intra-operatively (P = 0.026). This study highlights some possible association between the anaesthetic management and the outcome of the procedure.

Effect of pneumoperitoneum with warmed humidified or standard-temperature carbon dioxide during laparoscopy on core body temperature, cardiorespiratory and thromboelastography variables, systemic inflammation, peritoneal response, and signs of postoperative pain in healthy mature dogs

OBJECTIVE To evaluate effects of pneumoperitoneum created with warmed humidified CO₂ (WHCO₂) during laparoscopy on core body temperature, cardiorespiratory and thromboelastography variables, systemic inflammation, peritoneal response, and signs of postoperative pain in healthy mature dogs. ANIMALS 6 mature purpose-bred dogs. PROCEDURES In a randomized crossover study, each dog was anesthetized twice, and pneumoperitoneum was created with standard-temperature CO₂ (STCO₂; 22°C and 0% relative humidity) and WHCO₂ (37°C and 98% relative humidity). Data were collected during each procedure, including core body temperature, cardiorespiratory and thromboelastography variables, and inflammatory biomarkers. Peritoneal biopsy specimens were collected and evaluated with scanning electron microscopy. Dogs were assessed for signs of postoperative pain. RESULTS Mean core body temperature was significantly lower (35.2°C; 95% confidence interval, 34.5° to 35.8°C) with WHCO₂ than with STCO₂ (35.9°C; 95% confidence interval, 35.3° to 36.6°C) across all time points. Cardiac index increased during the procedure for both treatments but was not significantly different between treatments. Thromboelastography variables did not differ significantly between treatments as indicated by the coagulation index. Subjective evaluation of peritoneal biopsy specimens revealed mesothelial cell loss with STCO₂. There was no significant difference in circulating C-reactive protein or interleukin-6 concentrations. There was a significant increase in the number of postoperative pain scores > 0 for the WHCO₂ treatment versus the STCO₂ treatment. CONCLUSIONS AND CLINICAL RELEVANCE Analysis of these data suggested that effects on evaluated variables attributable to the use of WHCO₂ for creating pneumoperitoneum in healthy mature dogs undergoing laparoscopy did not differ from effects for the use of STCO₂.

Comparison of Dexmedetomidine-Ketamine-Midazolam and Isoflurane for Anesthesia of Black-tailed Prairie Dogs (Cynomys ludovicianus)

Few studies evaluate anesthesia in black-tailed prairie dogs (Cynomys ludovicianus). Isoflurane inhalant anesthesia is used in this species most commonly, but injectable protocols are poorly described. Here we compared the physiologic effects, including anesthetic depth, vital signs, and hematologic changes, of anesthetic protocols using isoflurane or a combination of dexmedetomidine, ketamine, and midazolam in black-tailed prairie dogs. In a randomized, complete crossover study design, intact male black-tailed prairie dogs (n = 9; age, 6 mo) were anesthetized by using a combination of dexmedetomidine (0.25 mg/kg IM), ketamine (40 mg/kg IM), and midazolam (1.5 mg/kg IM). For reversal, atipamezole (0.15 mg/kg) and flumazenil (0.05 mg/kg) were administered 45 min after induction. For comparison, isoflurane was administered at 5% in 100% oxygen at 5 L/min in an anesthetic induction chamber, followed by maintenance isoflurane 2% in 2 L/min oxygen through a tight-fitting facemask for 45 min. Induction and recovery time, respiratory rate, heart rate, body temperature, SpO₂, indirect blood pressure, and reflexes were monitored every 5 min during the anesthetic period. Blood samples for venous blood gases, PCV, and refractometric total protein were obtained from the cranial vena cava at 5 min and 45 min. Both protocols appeared to achieve safe and effective anesthesia. Except for blood pressure, all vital signs differed between the 2 treatments. Isoflurane anesthesia resulted in a slightly longer induction and lower respiratory rate and body temperature but increased likelihood of absent reflexes. DKM anesthesia resulted in a faster induction and less hypothermia but also prolonged recovery and lower heart rate and SpO₂ readings. These findings suggest that isoflurane provides a more stable and consistent anesthetic plane, whereas dexmedetomidine-ketamine-midazolam anesthesia may be an effective alternative for short procedures that require fast induction and limited analgesia.

Prolonged Recovery From General Anesthesia Possibly Related to Persistent Hypoxemia in a Draft Horse

Horses are susceptible to developing large areas of pulmonary atelectasis during recumbency and anesthesia. The subsequent pulmonary shunt is responsible for significant impairment of oxygenation. Since ventilation perfusion mismatch persists into the post-operative period, hypoxemia remains an important concern in the recovery stall. This case report describes the diagnosis and supportive therapy of persistent hypoxemia in a 914 kg draft horse after isoflurane anesthesia. It highlights how challenging it can be to deal with hypoxemia after disconnection from the anesthesia machine and how life-threatening it can become if refractory to treatment. Furthermore, it stresses the point on the interactions between hypoxemia and other factors, such as residual drug effects and hypothermia, that should also be considered in the case of delayed recovery from general anesthesia.

Effect of an intraoperative infusion of amino acids on body temperature, serum biochemistry, serum insulin and recovery variables in healthy dogs undergoing ovariohysterectomy

Change in body temperature (BT), serum biochemistry and recovery variables were compared after infusion of amino acids (AA) or lactated Ringer's solution (LRS) in dogs undergoing ovariohysterectomy. Dogs received eight parts 10 per cent AA and two parts LRS (AA, n=10) or only LRS (CG, n=10) at 10 ml/kg/hour during 90 minutes of anaesthesia. BT was measured during anaesthesia and 60 minutes of recovery. Extubation time and shivering were noted. Serum samples were obtained before anaesthesia (T0), end of anaesthesia (T90) and 18 hours after (T18h). Friedman, Mann-Whitney, Kruskal-Wallis or Fisher's exact tests were used for analysis. A decrease in BT of -2.16 (-1.59 to -3.24)°C for group AA and -2.79 (-1.98 to -4.52)°C for group CG was different (P=0.02). Time to extubation was 5 (3-9) minutes for group AA and 9 (5-15) minutes for group CG and was different (P=0.01). Only 30 per cent of dogs in group AA and 100 per cent of dogs in group CG shivered during recovery (P=0.003). Glucose, insulin and blood urea nitrogen at T90 were higher than T0 and T18h for group AA. Dogs receiving intraoperative infusion of AA had a higher BT, extubated sooner and shivered less than control dogs at recovery from anaesthesia.

AAFP Feline Anesthesia Guidelines

AIM

The overarching purpose of the AAFP Anesthesia Guidelines (hereafter referred to as the 'Guidelines') is to make anesthesia and sedation safer for the feline patient. Scope and accessibility: It is noteworthy that these are the first exclusively feline anesthesia guidelines authored by an expert panel, making them particularly useful as an extensively referenced, practical resource for veterinary practice teams. Because much of the key content is presented in tabular or visual format, the Guidelines have a high level of accessibility and convenience that invites regular usage. While the recommendations in the Guidelines focus primarily on client-owned cats, the content is also applicable to community-sourced animals with an unknown medical history.

A retrospective study of anesthesia for subcutaneous ureteral bypass placement in cats: 27 cases

The goals of this retrospective clinical case series study were to describe the management of anesthesia, and to report perioperative complications in cats undergoing subcutaneous ureteral bypass (SUB) placement due to ureteral obstruction. Medical records of client-owned cats with ureteral obstruction and anesthetized for SUB placement between 2012 and 2015 in a veterinary teaching hospital were reviewed. Twenty-seven cases were identified. Duration of anesthesia and surgery (mean ± standard deviation) were 215 ± 42 min and 148 ± 36 min, respectively. Hypothermia was the most common intraoperative complication. Hypotension, hypocapnia, hypertension and bradycardia were also frequently observed. Out of 22 cats who experienced intraoperative hypotension, 17 received inotropes and vasopressors. There was a significant decrease in creatinine (P=0.008) and total solids (P=0.007) after SUB placement when compared with baseline values. Postoperative complications included pain, anorexia, nausea, hypertension, and urinary tract-related problems. No death occurred in the postoperative period. Successful management of anesthesia for SUB placement involves rigorous anesthetic monitoring and immediate treatment of complications. Perioperative complications appear to be common. This study could not identify risk factors associated with this procedure.

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.

Injectable anaesthesia for adult cat and kitten castration: effects of medetomidine, dexmedetomidine and atipamezole on recovery

Objectives Rapid recovery from injectable anaesthesia benefits cat shelter neutering programmes. The effects of medetomidine, dexmedetomidine and atipamezole on recovery were evaluated in adult cats and kittens (⩽6 months old). Methods One hundred healthy male cats (age range 2-66 months, weight range 0.7-5.3 kg) admitted forneutering were randomly allocated to groups of 25. Anaesthesia was induced with 60 mg/m2 ketamine, 180 µg/m2 buprenorphine, 3 mg/m2 midazolam and either 600 µg/m2 medetomidine (groups M and MA) or 300 µg/m2 dexmedetomidine (groups D and DA) intramuscularly (IM). Groups MA and DA also received 1.5 mg/m2 atipamezole IM after 40 mins. Preparation time, surgical time, and times to sternal recumbency and standing were recorded. Data were analysed using the Kruskall-Wallis test, unpaired t-tests and ANOVA. Statistical significance was deemed to be P ⩽0.05. Results Groups did not differ significantly in age, body weight, preparation or surgical time. The time to sternal recumbency in group MA (64 ± 34 mins) was less than in group M (129 ± 32 mins), and in group DA it was less than in group D (54 ± 6 mins vs 110 ± 27 mins) ( P <0.001). There were no differences in duration of recovery to sternal recumbency between groups M and D or MA and DA. The time to standing in group MA (79 ± 51 mins) was less than in group M (150 ± 38 mins) ( P <0.001), and in group DA it was less than in group D (70 ± 22 mins vs 126 ± 27 mins) ( P <0.01). Time to standing in group D (126 ± 27 mins) was less than in group M (150 ± 38 mins) (P <0.05). Time to standing in groups DA and MA were not different. Kittens recovered faster than adults after atipamezole. Minimal adverse effects were seen. Conclusions and relevance Atipamezole reliably reduced recovery time after anaesthesia incorporating either dexmedetomidine or medetomidine; however, the choice of dexmedetomidine or medetomidine had little effect. Recovery was faster in kittens.