Microcirculation assessment of dexmedetomidine constant rate infusion during anesthesia of dogs with sepsis from pyometra: a randomized clinical study.

OBJECTIVE: To compare dexmedetomidine and fentanyl constant rate infusions in anesthetic protocols for septic dogs with pyometra, using microcirculatory, hemodynamic and metabolic variables. STUDY DESIGN: Randomized clinical study. ANIMALS: A total of 33 dogs with pyometra with two or more systemic inflammatory response syndrome variables undergoing ovariohysterectomy. METHODS: Dogs were randomized into two groups: group DG, dexmedetomidine (3 µg kg-1 hour-1; 17 dogs) and group FG, fentanyl (5 µg kg-1 hour-1; 16 dogs) infused during isoflurane anesthesia and mechanical ventilation. Microcirculation flow index (MFI), total vessel density and De Backer score were assessed using orthogonal polarization spectral imaging at the sublingual site. Heart rate, invasive blood pressure, temperature, arterial blood gas analysis and lactate concentration were obtained at various time points. Variables were recorded at baseline (BL), immediately before (T0), 30 (T30) and 60 (T60) minutes after infusion, and 60 minutes after surgery. Data were analyzed using the Shapiro-Wilk test. To compare variables between groups, the unpaired Student t test was used. Comparison between evaluation time points was performed with two-way anova for repeated measures. Where statistical significance was detected, the Bonferroni post hoc test was used. RESULTS: MFI was significantly higher in group FG at T30. Mean arterial pressure at T30 was higher in group DG (89 ± 15 mmHg) than in group FG (72 ± 13 mmHg). Lactate concentrations were not significantly different between groups at each time point. Both groups had similar clinical outcomes (mortality, extubation time and occurrence of hypotension and bradyarrhythmias). CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine (3 µg kg-1 hour-1) without a loading dose can be included in the maintenance of anesthesia in dogs with pyometra and sepsis without compromising microcirculation and hemodynamic values when compared with fentanyl (5 µg kg-1 hour-1).

Cyclooxygenases 1 and 2 inhibition and analgesic efficacy of dipyrone at different doses or meloxicam in cats after ovariohysterectomy.

OBJECTIVE: To evaluate the cyclooxygenases (COX) inhibition, adverse effects and analgesic efficacy of dipyrone or meloxicam in cats undergoing elective ovariohysterectomy. STUDY DESIGN: Prospective, blinded, randomized, clinical study. ANIMALS: A total of 30 healthy young cats. METHODS: The cats were randomly assigned to three postoperative groups: D25 (dipyrone 25 mg kg-1 every 24 hours), D12.5 (dipyrone 12.5 mg kg-1 every 12 hours) and M (meloxicam 0.1 mg kg-1 every 24 hours). In the first 24 hours, the drugs were administered intravenously (IV), and then orally for 6 (dipyrone) or 3 days (meloxicam). Prostanoids thromboxane B2 and prostaglandin E2 concentrations served as indicators of COX activity and, with physiological variables and pain and sedation scores, were measured for 24 hours after first analgesic administration. Rescue analgesia (tramadol, 2 mg kg-1 IV) was provided if Glasgow feline composite measure pain scale (CMPS-Feline) ≥5. Laboratory tests included symmetric dimethylarginine and adverse effects were evaluated regularly up to 7 and 10 days after surgery, respectively. Parametric and nonparametric data were analyzed with two-way anova and Kruskal-Wallis tests, respectively (p < 0.05). RESULTS: In the first half hour after analgesic administration, COX-1 activity was close to zero and remained significantly lower than before drug administration for 24 hours in all groups. The inhibition of COX-2 activity was significant for 30 minutes in all groups and up to 4 hours in group M. No alterations in laboratory tests or significant adverse effects were observed. Pain scores and need for rescue analgesia did not differ statistically among groups. CONCLUSIONS: Dipyrone at both doses and meloxicam provided a nonselective inhibition of COX-1 and -2 activities and effective analgesia without causing significant adverse effects or laboratory tests alterations. CLINICAL RELEVANCE: Dipyrone at both doses provides equally effective analgesia without causing adverse effects in cats undergoing ovariohysterectomy.

Effects of a diet enriched with eicosapentaenoic, docosahexaenoic and glutamine on cytokines as immunological markers for systemic inflammation in bitches before and after ovariohysterectomy.

The post-operative period can generate immunological stress and can be modulated through supplementation with the omega-3 series of polyunsaturated fatty acids. This study aimed to evaluate the effects of diets enriched with high doses of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids and glutamine on inflammatory mediators in dogs before and after ovariohysterectomy (OVH). Twelve female dogs were divided into two groups: group A was fed a commercial diet without the addition of EPA and DHA, and group B was fed an experimental diet enriched with EPA and DHA (0.2 g/100 kcal). Experimental diet intake initiated 21 days before surgery and continued until 30 days after OVH. Parameters measured were serum cytokines (TNF-α, IL-6 and IL-10), C-reactive protein (CRP), IGF-1, lymphoproliferation and body composition before and after surgery. Statistical analyses were performed with SAS software considering the effects of age and diet and their interactions, and means were compared by the Tukey test. There was no difference between groups in body weight (p = .682), lean mass (p = .101) and body fat (p = .103). There were no group differences in serum concentrations of TNF-α, IL-6, IL-10, IGF-1, CRP and the percentage of lymphocyte proliferation. However, a time effect for TNF-α was observed (p < .001), in which T0P (10 days after the surgical procedure) presented lower values of this cytokine when compared to the other evaluation time points; and interaction effects between group and time were observed for serum concentrations of IL-6 (p < .001) and IL-10 (p = .002). OVH procedure was not considered invasive enough to increase inflammatory cytokines after 30 days of surgery, as well as the dosage of the EPA and DHA used before and after the surgery did not modulate the inflammatory markers.

Comparison of pulse pressure variation versus echocardiography-derived stroke volume variation for prediction of fluid responsiveness in mechanically ventilated anesthetized dogs.

OBJECTIVE: To evaluate the ability and accuracy of aortic flow velocity-time integral variation (ΔVTI) and peak aortic velocity variation (ΔVpeak) compared with pulse pressure variation (PPV) to predict fluid responsiveness in mechanically ventilated dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: A group of 50 mechanically ventilated dogs with spontaneous hypotension during orthopedic or oncologic surgery. METHODS: Investigations were performed in the surgery room. When mean arterial pressure (MAP) decreased to <65 mmHg, measurements were performed before and after a fluid challenge (lactated Ringer's solution 5 mL kg-1 over 15 minutes). Responders were defined as a change in stroke volume (SV; transesophageal Doppler) ≥15%. Data were analyzed using paired/unpaired t test or Mann-Whitney/Wilcoxon test when appropriate and receiver operating characteristics (ROC) curves; a p value <0.05 was considered statistically significant. RESULTS: After the fluid challenge, 35 (70%) of 50 dogs were responders with significant increases in SV and decreases in PPV; 15 dogs were nonresponders. ΔVTI and ΔVpeak correlated with a 15% increase in SV. The optimum cut-off value for PPV was 15.6% (sensitivity, 88%; specificity, 100%), for ΔVTI was 10.65% (sensitivity, 65%; specificity, 100%) and for ΔVpeak was 10.15% (sensitivity, 80%; specificity, 100%). The area under the ROC curve for PPV was (0.93 ± 0.08) and for ΔVpeak was (0.89 ± 0.09), before fluid challenge. The gray zone area spread from 6.15% to 15.6% for PPV (18 dogs), 2.45% to 10.65% for ΔVTI (22 dogs) and 0.6% to 10.15% for ΔVpeak (25 dogs). CONCLUSIONS: When using mechanical ventilation, ΔVTI and ΔVpeak predicted fluid responsiveness with the same ability as PPV, based on the area under the ROC curve analysis. However, PPV showed great accuracy demonstrated by a narrower gray zone that included fewer individuals. CLINICAL RELEVANCE: ΔVTI and ΔVpeak can be used as indices of fluid responsiveness in anesthetized dogs.

Ultrasound-guided continuous block of median and ulnar nerves in horses: development of the technique.

OBJECTIVE: To develop a technique for ultrasound-guided continuous median and ulnar peripheral nerve block in horses. STUDY DESIGN: Anatomical and prospective experimental study. ANIMALS: A total of 16 thoracic limbs from horse cadavers and 18 adult horses. METHOD: This study was conducted in three phases. Phase 1: Dissection of median and ulnar nerves in the antebrachial region of two cadaver limbs to identify localizing landmarks. Description of sonoanatomy in 14 cadaver limbs using ultrasound-guided perineural infiltration of a combination of cellulose gel (5 mL), contrast medium (4 mL) and methylene blue (1 mL). Catheters were inserted between the perineural sheath and epineurium in six limbs, followed by computed tomography. Phase 2: Ultrasonographic images of the limbs of 18 healthy horses of different breeds were used to define an acoustic window and optimize the approach to nerves. Phase 3: Two case reports of horses with chronic pain of different etiologies. Catheters were inserted between the epineurium and paraneural sheath of the median and/or ulnar nerves guided by ultrasound, followed by continuous infusion of 0.4% ropivacaine. RESULTS: Information from phase 1 was used to direct needle insertion, solution dispersion and catheter implantation in phase 2, which resulted in 100% technique accuracy. In response to the peripheral nerve block, pain reduction was apparent in the two clinical cases by increased weight bearing in affected limbs and decreased requirement for systemic analgesic medications. No local reactions were observed. CONCLUSIONS AND CLINICAL RELEVANCE: The ultrasound technique allowed real-time visualization of needle, catheter and drug dispersion and resulted in a high success rate for nerve blocks. The horses administered a median and ulnar nerve block exhibited no discomfort or signs of infection at the catheter insertion site. Further studies are warranted to validate the efficacy of this technique.

Effects of 12 and 17 cmH2O positive end-expiratory pressure applied after alveolar recruitment maneuver on pulmonary gas exchange and compliance in isoflurane-anesthetized horses.

OBJECTIVE: To compare static compliance (Cst) and alveolar-arterial oxygen tension difference [P(a-a)O2] between positive end-expiratory pressures (PEEP) of 7, 12 and 17 cmH2O applied after an alveolar recruitment maneuver (RM) in isoflurane-anesthetized horses. STUDY DESIGN: Prospective, randomized, clinical study. ANIMALS: A group of 30 healthy adult horses undergoing arthroscopic surgery. METHODS: Animals in dorsal recumbency and mechanically ventilated with a tidal volume of 14 mL kg-1 and 7 cmH2O PEEP (control; n = 6) were subjected to an RM by increasing PEEP from 7 to 22 cmH2O in 5 cmH2O increments at 5 minute intervals, and then decreased similarly to PEEP of 17 (RM17; n = 8), 12 (RM12; n = 8) or 7 cmH2O (RM7; n = 8). Cst and P(a-a)O2 were assessed prior to (baseline) and after the RM at 5, 10, 15, 20, 40, 60 and 80 minutes after achieving each target PEEP, and during recovery from anesthesia. RESULTS: Post-RM improvements on P(a-a)O2 were maintained (baseline versus 80 minutes) in RM12 [216 ± 77 mmHg (28.8 ± 10.3 kPa) versus 194 ± 39 mmHg (25.9 ± 5.2 kPa)] and RM17 [180 ± 86 mmHg (24.0 ± 11.6 kPa) versus 136 ± 75 mmHg [18.2 ± 10.0 kPa]). The improvements on Cst were maintained only in RM12 (0.80 ± 0.13 versus 0.98 ± 0.13 mL cmH2O-1 kg-1). No such improvements were observed in RM7 and control. No significant differences were observed between groups during recovery from anesthesia. CONCLUSIONS: and clinical relevance The 12 and 17 cmH2O PEEP can be used to maintain the improvements on P(a-a)O2 obtained after an RM. Only 12 cmH2O PEEP maintained the post-RM increase on Cst. Such variables were not influenced by the 7 cmH2O PEEP.

Postoperative pain and short-term complications after two elective sterilization techniques: ovariohysterectomy or ovariectomy in cats.

BACKGROUND: Surgical sterilization of cats is one of the most commonly performed procedures in veterinary practice and it can be accomplished by two different techniques: ovariohysterectomy (OVH) or ovariectomy (OVE). Although there is an apparent preference for OVH in United States and Canada, OVE seems to be the standard of care in many European countries due to its advantages, such as a smaller surgical incision and potentially less complications associated with surgical manipulation of the uterus. The aim of this randomized, blind, prospective study was to compare postoperative pain and short-term complications in cats undergoing ovariohysterectomy or ovariectomy. METHODS: Twenty female cats were randomly assigned into two groups (OVH, n = 10 and OVE, n = 10). Pain was assessed prior to surgery (baseline) and 1, 2, 4, 8 12 and 24 h after the procedure using pain and sedation scales, physiologic parameters and blood glucose levels. Short-term complications were evaluated in the early postoperative period and reassessed at day 7 and day 10. RESULTS: Changes in cardiovascular parameters were not clinically relevant, however cats in OVH group had higher heart rates at T1 h compared with baseline (p = 0.0184). Blood glucose levels in OVH group were also higher at T1 h compared with baseline (p = 0.0135) and with OVE group (p = 0.0218). Surgical time was higher in OVH group (p = 0.0115). Even though no significant differences in pain scores were observed between groups or time points, cats in OVH group had greater need for rescue analgesia compared with OVE (2/10 and 0/10, respectively). Complications were not observed in any cat during surgery, at days 7 and 10 postoperatively or at discharge. CONCLUSIONS: Both surgical techniques promoted similar intensity of postoperative pain in cats and there were no short-term complications throughout the study's evaluation period. Therefore, both techniques may be indicated for surgical sterilization of cats, according to the surgeon's preference and expertise. Cats that underwent ovariectomy did not require rescue analgesia and surgical time was shorter in that group.

Clinical monitoring of cardiac output assessed by transoesophageal echocardiography in anaesthetised dogs: a comparison with the thermodilution technique.

BACKGROUND: Cardiac output (CO) is an important haemodynamic parameter to monitor in patients during surgery. However, the majority of the techniques for measuring CO have a limited application in veterinary practice due to their invasive approach and associated complexity and risks. Transoesophageal echocardiography (TEE) is a technique used to monitor cardiac function in human patients during surgical procedures and allows CO to be measured non-invasively. This prospective clinical study aimed to compare the transoesophageal echocardiography using a transgastric view of the left ventricular outflow tract (LVOT) and the thermodilution (TD) technique for the assessment of CO during mean arterial pressure of 65-80 mmHg (normotension) and <65 mmHg (hypotension) in dogs undergoing elective surgery. Eight dogs were pre-medicated with acepromazine (0.05 mg/kg, IM), tramadol (4 mg/kg, IM) and atropine (0.03 mg/kg, IM), followed by anaesthetic induction with propofol (3-5 mg/kg IV) and maintenance with isoflurane associated with a continuous infusion rate of fentanyl (bolus of 3 µg/kg followed by 0.3 µg/kg/min). The CO was measured by TEE (COTEE) and TD (COTD) at the end of expiration during normotension and hypotension (induced by isoflurane). RESULTS: There was a strong positive correlation between COTEE and COTD ​​(r = 0.925; P < 0.0001). The bias between COTD and COTEE was 0.14 ± 0.29 L/min (limits of agreement, -0.44 to 0.72 L/min). The percentage error of CO measured by the two methods was 12.32%. In addition, a strong positive correlation was found between COTEE and COTD during normotension (r = 0.995; P < 0.0001) and hypotension (r = 0.78; P = 0.0223). CONCLUSIONS: The results of this study indicated that the transgastric view of the LVOT by TEE was a minimally invasive alternative to clinically monitoring CO in dogs during anaesthesia. However, during hypotension, the CO obtained by TEE was less reliable, although still acceptable.

Pulse pressure variation as a guide for volume expansion in dogs undergoing orthopedic surgery.

OBJECTIVE: To investigate whether pulse pressure variation (PPV) can predict fluid responsiveness in healthy dogs during clinical surgery. STUDY DESIGN: Prospective clinical study. ANIMALS: Thirty-three isoflurane-anesthetized dogs with arterial hypotension during orthopedic surgery. METHODS: Fluid challenge with lactated Ringer's solution (15 mL kg-1 in 15 minutes) was administered in mechanically ventilated dogs (tidal volume 10 mL kg-1) with hypotension [mean arterial pressure (MAP) < 65 mmHg]. The volume expansion was considered effective if cardiac output (CO; transesophageal Doppler) increased by ≥ 15%. Cardiopulmonary data were analyzed using two-way ANOVA, receiver operating characteristics (ROC) curves and Spearman coefficient; p < 0.05 was considered significant. RESULTS: Effective volume expansion, mean ± standard deviation 42 ± 4% increase in CO (p < 0.0001) was observed in 76% of the dogs, resulting in a decrease in PPV (p < 0.0001) and increase in MAP (p < 0.0001), central venous pressure (CVP; p = 0.02) and ejection fraction (p < 0.0001) compared with before the fluid challenge. None of these changes occurred when volume expansion resulted in a nonsignificant CO increase of 4 ± 5%. No significant differences were observed in blood gas analysis between responsive and nonresponsive dogs. The increase in CO was correlated with the decrease in PPV (r = -0.65; p < 0.0001) but absolute values of CO and PPV were not correlated. The PPV performance (ROC curve area: 0.89 ± 0.06, p = 0.0011) was better than that of CVP (ROC curve area: 0.54 ± 0.12) and MAP (ROC curve area: 0.59 ± 0.13) to predict fluid responsiveness. The best cut-off for PPV to distinguish responders and nonresponders was 15% (50% sensitivity and 96% specificity). CONCLUSIONS AND CLINICAL RELEVANCE: In mechanically ventilated, healthy, isoflurane-anesthetized dogs, PPV predicted fluid responsiveness to volume expansion, and MAP and CVP did not show such applicability.

Ventilation distribution assessed with electrical impedance tomography and the influence of tidal volume, recruitment and positive end-expiratory pressure in isoflurane-anesthetized dogs.

OBJECTIVE: To examine the intrapulmonary gas distribution of low and high tidal volumes (VT) and to investigate whether this is altered by an alveolar recruitment maneuver (ARM) and 5 cmH2O positive end-expiratory pressure (PEEP) during anesthesia. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Fourteen client-owned bitches weighing 26 ± 7 kg undergoing elective ovariohysterectomy. METHODS: Isoflurane-anesthetized dogs in dorsal recumbency were ventilated with 0 cmH2O PEEP and pressure-controlled ventilation by adjusting the peak inspiratory pressure (PIP) to achieve a low (7 mL kg-1; n = 7) or a high (12 mL kg-1; n = 7) VT. Ninety minutes after induction (T90), an ARM (PIP 20 cmH2O for 10 seconds, twice with a 10 second interval) was performed followed by the application of 5 cmH2O PEEP for 35 minutes (RM35). The vertical (ventral=0%; dorsal=100%) and horizontal (right=0%; left=100%) center of ventilation (CoV), four regions of interest (ROI) (ventral, central-ventral, central-dorsal, dorsal) identified in electrical impedance tomography images, and cardiopulmonary data were analyzed using two-way repeated measures anova. RESULTS: The low VT was centered in more ventral (nondependent) areas compared with high VT at T90 (CoV: 38.8 ± 2.5% versus 44.6 ± 7.2%; p = 0.0325). The ARM and PEEP shifted the CoV towards dorsal (dependent) areas only during high VT (50.5 ± 7.9% versus 41.1 ± 2.8% during low VT, p = 0.0108), which was more distributed to the central-dorsal ROI compared with low VT (p = 0.0046). The horizontal CoV was centrally distributed and cardiovascular variables remained unchanged throughout regardless of the VT, ARM, and PEEP. CONCLUSIONS AND CLINICAL RELEVANCE: Both low and high VT were poorly distributed to dorsal dependent regions, where ventilation was improved following the current ARM and PEEP only during high VT. Studies on the role of high VT on pulmonary complications are required.

Comparison of preoperative tramadol and pethidine on postoperative pain in cats undergoing ovariohysterectomy.

BACKGROUND: A variety of analgesic agents are available, and which one can be used in dogs and cats is a highly controversial issue, existing however a fear in the use of opiates due to possible adverse effects that these drugs can cause. The aim of this study was to compare the analgesic effect provided by the administration of tramadol or pethidine on early postoperative pain of cats undergoing ovariohysterectomy in a double-blind prospective study. Fourty-two animals were randomly assigned into three groups. Pet received pethidine (6 mg/kg), Tra 2 received tramadol (2 mg/kg) and Tra 4 received tramadol (4 mg/kg); all intramuscularly and associated with acepromazine (0.1 mg/kg). The efficacy of each analgesic regimen was evaluated prior to surgery (baseline - TBL), during surgery and 1, 3 and 6 hours after extubation with subjective pain scale, physiologic parameters, serum concentrations of glucose, cortisol and IL-6. RESULTS: Changes in cardiovascular system were not clinically relevant. There were no significant differences in pain scores (P > 0.05) during the study, although the number of rescue analgesia was significantly higher (P < 0.05) at Pet group (5/14) than Tra 4 group (0/14), whereas in Tra 2, two animals (2/14) required additional analgesia. The serum cortisol values of Pet group were significantly higher at T1h T3h (P < 0.05) and T6h (P < 0.01) when compared to baseline (induction), also it was noticed a significant difference among the groups at T6h (Pet values were higher than Tra 2 and Tra 4; P < 0.05). CONCLUSIONS: Tramadol provided adequate analgesia and it was more effective than pethidine to at least six hours for the studied animals. At the higher dose (4 mg/kg) tramadol is probably more effective, since rescue analgesia was not necessary. No significant changes were observed physiological parameter that could contraindicate the use of these opioid in described doses, for the feline species.

Evaluation of the effects of methadone and tramadol on postoperative analgesia and serum interleukin-6 in dogs undergoing orthopaedic surgery.

BACKGROUND: Acute postsurgical pain is of great interest due to potential risk of becoming chronic if not treated properly, worsening patient's recovery and quality of life. Twenty-eight dogs with ruptured cruciate ligaments were divided into three groups that received intramuscular injections of 4 mg/kg of tramadol (TRA), 0.5 mg/kg of methadone (MET0.5), or 0.7 mg/kg of methadone (MET0.7). Physiological parameters (heart and respiratory rates and blood pressure) were evaluated at specified times: baseline (TBL), 1 (T1), 2 (T2), 4 (T4), 6 (T6), and 24 (T24) hours after premedication. Pain scores were described by visual analogue scale (VAS), modified Glasgow Composite, and Colorado University Acute Pain scales. Blood samples for measurement of interleukin (IL)-6 were collected at TBL, T1, T6, and T24. This was a prospective, randomised investigation to evaluate the efficacy of tramadol and methadone as premedications in dogs undergoing osteotomies. RESULTS: There were no statistically significant differences between groups with respect to age, weight, gender, surgery time, and time to extubation. Heart rate, respiratory rate, and blood pressure values were maintained within acceptable ranges, and a reduction was observed at T2 in MET0.5 and MET0.7 compared with TBL. Increases in VAS scores were observed in TRA at T4 compared with TBL, T1, and T24 and between T1 and T6 (p < 0.001). In MET0.5, there was significant increase in VAS score at T4 compared with T1 (p < 0.001). TRA and MET0.5 showed significantly higher mean ± SD VAS scores (3.4 ± 2.5 and 2.5 ± 2.6, respectively) than MET0.7 (1.1 ± 1.5) at T4 (p < 0.001). TRA showed greater demand of rescue analgesia (four animals in T4 and two in T6) (p < 0.037). There were no statistically significant differences in sedation scores, Colorado Scale scores, or interleukin levels between groups and time points. CONCLUSIONS: Methadone given as premedication in doses of 0.7 mg/kg was better at controlling pain compared with lower doses and tramadol. However, dosage increases, administered as rescue analgesia, promoted adequate pain control even in tramadol group. Influence of these analgesics on IL-6 release could not be demonstrated, but significant levels were not found.

Effect of postoperative xylazine administration on cardiopulmonary function and recovery quality after isoflurane anesthesia in horses.

OBJECTIVE: To evaluate equine cardiopulmonary function and recovery quality after administration of 0.25 or 0.50 mg/kg xylazine intravenously (IV) during recovery. STUDY DESIGN: Randomized, blinded, prospective, clinical study. ANIMALS: Horses (n = 20). METHODS: During recovery after 3 hours of isoflurane anesthesia for arthroscopic surgery, horses were administered either 0.25 mg/kg (G25, n = 10) or 0.50 mg/kg (G50, n = 10) xylazine intravenously. Vital signs and arterial blood samples were obtained during recovery before sedation (baseline), 5, 10, 20, 30, and 45 minutes after xylazine and 30 minutes after standing. The quality of recovery scores ranged from 10 to 72 (10 = best, 72 = worst). RESULTS: G25 horses recovered faster (mean ± SD, 33 ± 5 min) than G50 horses (50 ± 7 min, P < .0001). Mean maximal decrease in arterial oxygen tension was 55 ± 11 mmHg in G25 (at 10 minutes; P < .05) and 54 ± 7 mmHg in G50 (at 20 minutes; P < .01). G25 group had a total recovery score (23 [range 18-29]) and number of attempts to stand (4 ± 2) greater than the G50 group (18 [10-23] and 1 ± 1, respectively; P < .001). CONCLUSIONS: Both doses of xylazine promoted a moderate and transient hypoxemia during recovery; however, the 0.5 mg/kg dose produced a longer and improved quality of recovery from anesthesia.

Tramadol plus metamizole combined or not with anti-inflammatory drugs is clinically effective for moderate to severe chronic pain treatment in cancer patients.

OBJECTIVE: To test the effectiveness and safety of tramadol plus metamizole combined or not with a non-steroidal anti-inflammatory drug (NSAID) for treating moderate to severe chronic neoplastic pain in dogs, and its impact on quality of life (QL). STUDY DESIGN: Prospective, uncontrolled, open-label, clinical study. ANIMALS: Sixty nine client-owned dogs with multiple forms of cancer and visual analog scale (VAS) pain score ≥ 40 after receiving NSAIDs for at least 7 days. METHODS: The MN group received metamizole + NSAID, MNT group received metamizole + NSAID + tramadol and MT group received metamizole + tramadol. Pain was scored by the 0 to 100 mm VAS (0 = no pain, 100 = worst pain) and analgesic therapy was considered effective if 25 mm differences in VAS scores were observed between day 0 and the follow ups. The QL was evaluated according to a 0 to 36 scoring method for dogs (0 = worst, 36 = best) and side effects were recorded. Data were registered at day 0 (baseline) and at the first and second follow ups (7 and 14 days after day 0, respectively). RESULTS: The MN group had less analgesia at day 7 (25%) and day 14 (42%) than MNT (59%, p = 0.0274; 76%, p = 0.0251, respectively) and MT groups (69%, p = 0.0151; 81%, p = 0.0341, respectively). The QL scores were lower in the MN group at the first (score 23) and second follow up (score 26) than in MNT (27, p = 0.0847; 30, p = 0.0002) and MT (28, p = 0.0384; 31, p = 0.0001) groups. Side effects were more commonly observed in the MN group (87%) than in MNT (24%, p < 0.0001) and MT groups (25%, p = 0.0003) at the first follow up. CONCLUSIONS AND CLINICAL RELEVANCE: Tramadol plus metamizole combined or not with NSAID were well tolerated and clinically effective to treat moderate to severe pain in dogs with cancer and improved QL.

Effects of positive end-expiratory pressure titration on gas exchange, respiratory mechanics and hemodynamics in anesthetized horses.

OBJECTIVE: To assess if positive end-expiratory pressure (PEEP) titration improves gas exchange and respiratory mechanics, without hemodynamic impairment in horses during anesthesia. DESIGN: Prospective, randomized study. ANIMALS: Thirteen isoflurane-anesthetized healthy horses. METHODS: After 60 minutes of anesthesia with spontaneous breathing, mechanical ventilation was initiated with an inspiratory-expiratory ratio of 1:2, PEEP of 5 cmH2O, tidal volume of 10-20 mL kg(-1) and respiratory rate adjusted to maintain normocapnia. Constant PEEP of 5 cmH2O was continued (control group; n = 6) or titrated (PEEP group; n = 7) by increasing and decreasing PEEP from 5 to 20 cmH2O at 15-minute intervals. The horses were instrumented with an arterial catheter to measure blood pressure and allow collection of blood for pH and blood gas analysis and a Swan-Ganz catheter for measurement of cardiac output (CO) using thermodilution. Cardiopulmonary assessment was recorded before PEEP titration and after 15 minutes at each PEEP value. RESULTS: In the PEEP group, static compliance (range) (Cst 278-463 mL cmH2O(-1)) was significantly higher and the shunt fraction (Q·s/Q·t 7-20%) and the alveolar-arterial oxygen difference [P(A-a)O2 95-325 mmHg] were significantly lower than in the control group [Cst of 246-290 mL cmH2O(-1), Q·s/Q·t of 16-19%, P(A-a)O2 of 253-310 mmHg; p < 0.05]. CO (mean ± SEM) was lower in the PEEP group (23 ± 2 L minute(-1)) at 20 cmH2O PEEP than in the control group (26 ± 4 L minute(-1), p < 0.05), with no significant changes in heart rate, blood pressure or central venous pressure. CONCLUSIONS: PEEP titration significantly improved gas exchange and lung compliance, with a small decrease in CO at the highest PEEP level. CLINICAL RELEVANCE: Gas exchange and respiratory mechanics impairment during inhalation anesthesia can be treated using PEEP titration from 5 to 20 cmH2O, without clinically important hemodynamic effects in healthy horses.

Effect of ephedrine and phenylephrine on cardiopulmonary parameters in horses undergoing elective surgery.

OBJECTIVE: To assess the cardiopulmonary effects of ephedrine and phenylephrine for management of isoflurane-induced hypotension in horses. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Fourteen isoflurane-anesthetized horses undergoing digital palmar neurectomy. METHODS: Ephedrine (EPH group; 0.02 mg kg(-1) minute(-1); n = 7) or phenylephrine (PHE group; 0.002 mg kg(-1) minute(-1); n = 7) was administered to all horses when mean arterial pressure (MAP) was <60 mmHg. The infusions were ended when the target MAP was achieved, corresponding to a 50% increase over the pre-infusion MAP (baseline). The horses were instrumented with an arterial catheter to measure blood pressure and allow the collection of blood for pH and blood-gas analysis and a Swan-Ganz catheter for measurement of cardiac output using thermodilution. Cardiopulmonary parameters were recorded at baseline and at 5, 30, 60 and 90 minutes after achieving the target MAP. RESULTS: In both groups, the MAP and systemic vascular resistance (SVR) increased significantly at 5, 30, 60 and 90 minutes post infusion compared to baseline (p < 0.05). The EPH group had a significant increase in cardiac index (CI) and systemic oxygen delivery index at 5, 30, 60 and 90 minutes post infusion compared to baseline (p < 0.05) and compared to the PHE group (p < 0.05). The PHE group had significantly higher SVR and no decrease in oxygen extraction compared with the EPH group at 30, 60 and 90 minutes post infusion (p < 0.05). No significant differences in ventilatory parameters were observed between groups after the infusion. CONCLUSIONS: Ephedrine increased the MAP by increasing CI and SVR. Phenylephrine increased MAP by increasing SVR but cardiac index decreased. Ephedrine resulted in better tissue oxygenation than phenylephrine. CLINICAL RELEVANCE: Ephedrine would be preferable to phenylephrine to treat isoflurane-induced hypotension in horses since it increases blood flow and pressure.

Effect of pressure support ventilation during weaning on ventilation and oxygenation indices in healthy horses recovering from general anesthesia.

OBJECTIVE: To determine if pressure support ventilation (PSV) weaning from general anesthesia affects ventilation or oxygenation in horses. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Twenty client-owned healthy horses aged 5 ± 2 years, weighing 456 ± 90 kg. METHODS: In the control group (CG; n = 10) weaning was performed by a gradual decrease in respiratory rate (fR ) and in the PSV group (PSVG; n = 10) by a gradual decrease in fR with PSV. The effect of weaning was considered suboptimal if PaCO2 > 50 mmHg, arterial pH < 7.35 plus PaCO2 > 50 mmHg or PaO2 < 60 mmHg were observed at any time after disconnection from the ventilator until 30 minutes after the horse stood. Threshold values for each index were established and the predictive power of these values was tested. RESULTS: Pressure support ventilation group (PSVG) had (mean ± SD) pH 7.36 ± 0.02 and PaCO2 41 ± 3 mmHg at weaning and the average lowest PaO2 69 ± 6 mmHg was observed 15 minutes post weaning. The CG had pH 7.32 ± 0.02 and PaCO2 57 ± 6 mmHg at weaning and the average lowest PaO2 48 ± 5 mmHg at 15 minutes post weaning. No accuracy in predicting weaning effect was observed for fR (p = 0.3474), minute volume (p = 0.1153), SaO2 (p = 0.1737) and PaO2 /PAO2 (p = 0.1529). A high accuracy in predicting an optimal effect of weaning was observed for VT > 10 L (p = 0.0001), fR /VT ratio ≤ 0.60 breaths minute(-1) L(-1) (p = 0.0001), VT /bodyweight > 18.5 mL kg(-1) (p = 0.0001) and PaO2 /FiO2 > 298 (p = 0.0002) at weaning. A high accuracy in predicting a suboptimal effect of weaning was observed for VT < 10 L (p = 0.0001), fR /VT ratio ≥ 0.60 breaths minute(-1) L(-1) (p = 0.0001) and Pe'CO2 ≥ 38 mmHg (p = 0.0001) at weaning. CONCLUSIONS AND CLINICAL RELEVANCE: Pressure support ventilation (PSV) weaning had a better respiratory outcome. A higher VT , VT /body weight, PaO2 /FiO2 ratio and a lower fR /VT ratio and Pe'CO2 were accurate in predicting the effect of weaning in healthy horses recovering from general anesthesia.

Evaluation of an onco-diet on body composition and inflammatory status of dogs with mammary tumor-Pilot study.

A high-protein hypercaloric diet enriched with glutamine and omega-3 polyunsaturated fatty acids was called an onco-diet. The goal was to verify the modulation of the inflammatory response and body composition of female dogs with mammary tumor after mastectomy, during onco-diet consumption, using a randomized, double-blinded, clinical trial. Six bitches (average age of 8.6 years) were allocated into Control Group-diet without glutamine, EPA and DHA supplementation; and six bitches (10.0 years) were allocated into Test-diet enriched with glutamine and omega-3. Serum measurements of TNF-α, IL-6, IL-10, IGF-1, C-reactive protein and determination of body composition were performed at pre- and post-surgical times. Statistical tests were used to compare the nutrient intake and dietary effects on inflammatory variables between the diets. No differences in concentrations of different cytokines (p>0.05) and C-reactive protein (CRP) (p = 0.51) were observed between the groups. The test group had a higher concentration of IGF-1 (p<0.05), higher percentage of muscle mass (p<0.01) and lower body fat (p<0.01), but the difference was present from initial and throughout the study. Onco-diet, enriched with glutamine and omega-3, in the amounts evaluated in this study, was not sufficient to modulate the inflammation and body composition of female dogs with mammary tumors submitted to unilateral mastectomy.

Effects of positive end-expiratory pressure titration and recruitment maneuver on lung inflammation and hyperinflation in experimental acid aspiration-induced lung injury.

BACKGROUND: In acute lung injury positive end-expiratory pressure (PEEP) and recruitment maneuver are proposed to optimize arterial oxygenation. The aim of the study was to evaluate the impact of such a strategy on lung histological inflammation and hyperinflation in pigs with acid aspiration-induced lung injury. METHODS: Forty-seven pigs were randomly allocated in seven groups: (1) controls spontaneously breathing; (2) without lung injury, PEEP 5 cm H2O; (3) without lung injury, PEEP titration; (4) without lung injury, PEEP titration + recruitment maneuver; (5) with lung injury, PEEP 5 cm H2O; (6) with lung injury, PEEP titration; and (7) with lung injury, PEEP titration + recruitment maneuver. Acute lung injury was induced by intratracheal instillation of hydrochloric acid. PEEP titration was performed by incremental and decremental PEEP from 5 to 20 cm H2O for optimizing arterial oxygenation. Three recruitment maneuvers (pressure of 40 cm H2O maintained for 20 s) were applied to the assigned groups at each PEEP level. Proportion of lung inflammation, hemorrhage, edema, and alveolar wall disruption were recorded on each histological field. Mean alveolar area was measured in the aerated lung regions. RESULTS: Acid aspiration increased mean alveolar area and produced alveolar wall disruption, lung edema, alveolar hemorrhage, and lung inflammation. PEEP titration significantly improved arterial oxygenation but simultaneously increased lung inflammation in juxta-diaphragmatic lung regions. Recruitment maneuver during PEEP titration did not induce additional increase in lung inflammation and alveolar hyperinflation. CONCLUSION: In a porcine model of acid aspiration-induced lung injury, PEEP titration aimed at optimizing arterial oxygenation, substantially increased lung inflammation. Recruitment maneuvers further improved arterial oxygenation without additional effects on inflammation and hyperinflation.

Comparison of epidural and systemic tramadol for analgesia following ovariohysterectomy.

The objective of the study was to compare epidural and systemic tramadol for postoperative analgesia in bitches undergoing ovariohysterectomy. Twenty animals, randomly divided into two groups, received either epidural (EPI) or intramuscular (IM) tramadol (2 mg/kg) 30 min before anesthetic induction. Analgesia, sedation, cardiorespiratory parameters, end-tidal isoflurane, blood catecholamines and cortisol, and arterial blood gases were measured at different time points up to 24 hr after agent administration. There were no differences between the two groups regarding cardiorespiratory parameters, end-tidal isoflurane, and pain scores. Two dogs in the IM and one in the EPI group required supplemental analgesia. Cortisol was increased (P<0.05) at 120 min (3.59 µg/dL and 3.27 µg/dL in the IM and EPI groups, respectively) and 240 min (2.45 µg/dL and 2.54 µg/dL in the IM and EPI groups, respectively) compared to baseline. Norepinephrine was also increased (P<0.05) at 120 min in both groups compared to baseline values. Epinephrine values were higher (P<0.05) in the IM group compared with the EPI group at 50 min, 120 min, and 1,440 min after tramadol administration. Epidural tramadol is a safe analgesic, but does not appear to have improved analgesic effects compared with IM administration.