Dose range finding study for the efficacy of meloxicam administered prior to sodium urate-induced synovitis in cats

ObjectiveTo determine the lowest efficacious dose of oral meloxicam for relieving pain in cats with a sodium urate (SU)-induced acute inflammatory synovitis.Study designRandomized, blinded, controlled, and four-way crossover study.AnimalsEight surgically neutered cats (four males, four females) paired according to sex.MethodsEach pair of cats was treated with 0 (placebo), 0.025, 0.05, or 0.075 mg kg^?1 oral meloxicam once daily for 4 days prior to injection, into alternating stifles, of 1 mL of 20 mg mL^?1 SU crystals, beginning with the right stifle. Each cat received each of the four treatments, separated by at least 21 days. Analgesic efficacy was evaluated based on objective (e.g., pressure mat data total force, contact pressure, and contact area) and subjective (e.g., scores for Analgesia Scale [AS], Lameness Scale [LS], and Visual Analog Scale [VAS]) outcome measures for pain assessment. All outcome measures were recorded before and during 30 hours after SU injection. The pre-defined primary outcome measure was the area under the response–time curve (AUC_0–30 hours) of the total force of the injected limb. Data were analyzed by analysis of variance. A sequential test procedure was applied and the test sequence stopped in case of a nonsignificant result.ResultsMeloxicam at doses of 0.05 and 0.075 mg kg^?1 day^?1 PO was significantly different from placebo for the pre-defined primary outcome measure (i.e., AUC_0–30 hours of total force). All tested meloxicam doses were lower than placebo for the subjective outcome measures (i.e., AUC_0–30 hours of AS, LS, and VAS).Conclusions and clinical relevanceThe lowest efficacious dose of meloxicam for relieving pain in cats with an SU-induced synovitis was 0.05 mg kg^?1 day^?1 PO according to the pre-defined primary outcome measure. However, lower doses may also be effective as seen in the subjective outcome measures.     

Detomidine-Propofol Anesthesia for Abdominal Surgery in Horses

OBJECTIVE: To evaluate propofol for induction and maintenance of anesthesia, after detomidine premedication, in horses undergoing abdominal surgery for creation of an experimental intestinal adhesion model. STUDY DESIGN: Prospective study. ANIMALS: Twelve horses (424 +/- 81 kg) from 1 to 20 years of age (5 females, 7 males). METHODS: Horses were premedicated with detomidine (0.015 mg/kg i.v.) 20 to 25 minutes before induction, and a propofol bolus (2 mg/kg i.v.) was administered for induction. Propofol infusion (0.2 mg/kg/min i.v.) was used to maintain anesthesia. The infusion rate was adjusted to maintain an acceptable anesthetic plane as determined by muscle relaxation, occular signs, response to surgery, and cardiopulmonary responses. Oxygen (15 L/min) was insufflated through an endotracheal tube as necessary to maintain the SpO2 greater than 90%. Systolic (SAP), mean (MAP), and diastolic (DAP) arterial pressures, heart rate (HR), electrocardiogram (ECG), respiratory rate (RR), SpO2 (via pulse oximetry), and nasal temperature were recorded at 15 minute intervals, before premedication and after induction of anesthesia. Arterial blood gas samples were collected at the same times. Objective data are reported as mean (+/-SD); subjective data are reported as medians (range). RESULTS: Propofol (2.0 mg/kg i.v.) induced anesthesia (mean bolus time, 85 sec) within 24 sec (+/-22 sec) after the bolus was completed. Induction was good in 10 horses; 2 horses showed signs of excitement and these two inductions were not smooth. Propofol infusion (0.18 mg/kg/min +/- 0.04) was used to maintain anesthesia for 61 +/- 19 minutes with the horses in dorsal recumbency. Mean SAP, DAP, and MAP increased significantly over time from 131 to 148, 89 to 101, and 105 to 121 mm Hg, respectively. Mean HR varied over time from 43 to 45 beats/min, whereas mean RR increased significantly over anesthesia time from 4 to 6 breaths/min. Mean arterial pH decreased from a baseline of 7.41 +/- 0.07 to 7.30 +/- 0.05 at 15 minutes of anesthesia, then increased towards baseline values. Mean PaCO2 values increased during anesthesia, ranging from 47 to 61 mm Hg whereas PaO2 values decreased from baseline (97 +/- 20 mm Hg), ranging from 42 to 57 mm Hg. Muscle relaxation was good and no horses moved during surgery: Recovery was good in 9 horses and acceptable in 3; mean recovery time was 67 +/- 29 minutes with 2.4 +/- 2.4 attempts necessary for the horses to stand. CONCLUSIONS: Detomidine-propofol anesthesia in horses in dorsal recumbency was associated with little cardiovascular depression, but hypoxemia and respiratory depression occurred and some excitement was seen on induction. CLINICAL RELEVANCE: Detomidine-propofol anesthesia is not recommended for surgical procedures in horses if dorsal recumbency is necessary and supplemental oxygen is not available (eg, field anesthesia).     

Student assessment of the educational benefits of using a CD-ROM for instruction of basic surgical skills

RATIONALE FOR STUDY: At Texas A&M University, introductory-level surgical lecture and laboratory notes were converted to a CD-ROM format that included illustrative photographs as well as instructional videos demonstrating the basic surgical skills that all students were required to master. The CD-ROM was distributed to all students in place of traditional paper notes in the second-year surgical class in the professional veterinary curriculum. The study reported here was designed to evaluate the educational benefits of the use of the CD-ROM in place of traditional paper notes by examining the attitudes and practices of students before and after exposure to the CD-ROM format. METHODOLOGY: An anonymous survey was distributed to students in the second-year introductory surgery course on the first day of class and again on the last day of class. Responses to questions were tabulated, response frequencies determined, and Chi-square analysis performed to determine differences between initial and final responses. RESULTS: On the final survey, 89 per cent of students responded that the instructional videos definitely helped them prepare for the laboratory, and 77 per cent responded that they were more likely to practice techniques learned from the CD-ROM videos than those learned from traditional study materials. The majority of students believed that the CD-ROM improved both the course (60 per cent) and their learning experience (62 per cent) as compared to traditional paper notes. CONCLUSIONS: Including instructional videos on the CD-ROM enhanced the educational experience of the students by promoting preparedness for laboratories and promoting practice of techniques learned from the videos outside of the laboratory.     

Evaluation of the Nonin 8600V Veterinary Pulse Oximeter in Anesthetized Horses

S_pO₂ values from the Nonin 8600V veterinary pulse oximeter, using a lingual clip-type, transmittance sensor applied to the tongue, were compared to directly-measured S_aO₂ values from a co-oximeter, calibrated for equine blood, in 5 halothane-anesthetized horse. Normocapnia was maintained with controlled ventilartion. The inspired oxygen concentration was varied by mixing nitrogen in oxygen to obtain S_pO₂ readings of approximately 60, 65, 70, 75, 80, 85, 90, 92, and 100%. At the time of each S_pO₂ recording, an arterial blood sample was collected for immediate analysis of S_aO₂. A total of sixty paired measurements were made. The results showed excellent data correlation with a bias (precision) of 0.55 (2.57) and an R-value of 0.98 over the entire S_aO₂ range tested. Based on these findings, the Nonin 8600V veterinary pulse oximeter, with the lingual sensor, performed accurately and reliably, and appears to be suitable for clinical use in anesthetized horses. (Vet Emerg & Crit Care, 1999: 13–18)     

COMPUTED TOMOGRAPHY AND BLOOD GAS ANALYSIS OF ANESTHETIZED BLOODHOUNDS WITH INDUCED PNEUMOTHORAX

Increasingly severe degrees of pneumothorax were produced in 6 adult anesthetized bloodhounds. Computed tomography (CT) of the thorax was performed on each dog to evaluate the effects of pneumo thorax on thoracic and on pulmonary cross-sectional area (TA and PA). Arterial PO₂ (PaO₂) and PCO₂ (PaCO₂), heart rate (HR), and mean arterial blood pressure (MAP) were determined and related to the severity of pneumothorax. Volumes of air equal to 1, 1.5 and 2 times functional residual capacity of the lung produced approximately 33%, 40%, and 50% reductions in pulmonary area respectively. These amounts of atelectasis correspond to a radiographically "moderate" degree of pneumothorax. As severity of pneumothorax increased, thoracic area consistently increased, PaO₂ consistently decreased, and PaCO₂ consistently increased, with all being statistically significant relationships (p<0.0001); but HR and MAP were variable and showed no statistical correlation to the degree of pneumothorax (p>0.2).     

Hypolipidemic effects of modified psyllium preparations

The hypolipidemic effects of two solid-state enzymatically modified psyllium preparations were compared to that of the original psyllium husks in hamsters. Hamsters were ad libitum fed 0.2 wt % cholesterol diets formulated to contain 12% cellulose or 5% cellulose plus 7% raw or enzymatically modified psyllium preparations. Psyllium additions to the diet did not significantly alter food consumption or the weekly mean hamster weight over the 5 weeks of feeding. However, the total weight gained over 35 days of feeding of modified psyllium Y-26-4, one of the modified psyllium preparations, was significantly lower, 48, 47, and 32% than that for the cellulose, raw psyllium, and modified psyllium Y-24-3 groups, respectively. At 35 days, psyllium feeding significantly reduced plasma total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol by 50-100% in comparison to cellulose feeding, with no significant differences between the psyllium preparations. Fecal dry weight was unaffected by dietary treatment. At days 29-31, fecal bile acid excretion was significantly increased by 30-70% with all three psyllium diets, with no significant differences between psyllium preparations. These results suggest that improving the functional properties of psyllium by solid-state enzymatic procedures, such that its incorporation into food products is feasible, does not alter psyllium-mediated hypolipidemic effects.     

PRACTICAL PROBLEMS WITH VETERINARY ANAESTHESIA MACHINES

Many types of anaesthetic machines are available to practicing veterinary surgeons, ranging from the obsolescent to the most modern. To practice anaesthesia safely, veterinary surgeons should understand the functions of the machines, vaporizers, and breathing systems with which they work. In addition, veterinary surgeons should employ procedures for evaluation of their anaesthetic equipment to assure, as much as possible, safety for their patients and the personnel who use the apparatus.     

Pharmacokinetics and selected behavioral responses to butorphanol and its metabolites in goats following intravenous and intramuscular administration

Objective To evaluate disposition of a single dose of butorphanol in goats after intravenous (IV) and intramuscular (IM) administration and to relate behavioral changes after butorphanol administration with plasma concentrations. Design Randomized experimental study. Animals Six healthy 3‐year‐old neutered goats (one male and five female) weighing 46.5 ± 10.5 kg (mean ± D). Methods Goats were given IV and IM butorphanol (0.1 mg kg^?1) using a randomized cross‐over design with a 1‐week interval between treatments. Heparinized blood samples were collected at fixed intervals for subsequent determination of plasma butorphanol concentrations using an enzyme linked immunosorbent assay (ELISA). Pharmacokinetic values (volume of distribution at steady state [Vd_SS], systemic clearance [Cl_TB], extrapolated peak plasma concentration [C₀] or estimated peak plasma concentration [C_MAX], time to estimated peak plasma concentration [T_MAX], distribution and elimination half‐lives [t_1/2], and bioavailability) were calculated. Behavior was subjectively scored. A two‐tailed paired t‐test was used to compare the elimination half‐lives after IV and IM administration. Behavioral scores are reported as median (range). A Friedman Rank Sums test adjusted for ties was used to analyze the behavioral scores. A logit model was used to determine the effect of time and concentration on behavior. A value of p < 0.05 was considered significant. Results Volume of distribution at steady state after IV administration of butorphanol was 1.27 ± 0.73 L kg^?1, and Cl_TB was 0.0096 ± 0.0024 L kg^?1 minute^?1. Extrapolated C₀ of butorphanol after IV administration was 146.5 ± 49.8 ng mL^?1. Estimated C_MAX after IM administration of butorphanol was 54.98 ± 14.60 ng mL^?1, and T_MAX was 16.2 ± 5.2 minutes; bioavailability was 82 ± 41%. Elimination half‐life of butorphanol was 1.87 ± 1.49 and 2.75 ± 1.93 hours for IV and IM administration, respectively. Goats became hyperactive after butorphanol administration within the first 5 minutes after administration. Behavioral scores for goats were significantly different from baseline at 15 minutes after IV administration and at 15 and 30 minutes after IM administration. Both time and plasma butorphanol concentration were predictors of behavior. Behavioral scores of all goats had returned to baseline by 120 minutes after IV administration and by 240 minutes after IM administration. Conclusions and Clinical Relevance The dose of butorphanol (0.1 mg kg^?1, IV or IM) being used clinically to treat postoperative pain in goats has an elimination half‐life of 1.87 and 2.75 hours, respectively. Nonpainful goats become transiently excited after IV and IM administration of butorphanol. Clinical trials to validate the efficacy of butorphanol as an analgesic in goats are needed.     

A Comparison of 2 Pluse Oximeters in Dogs

Readings from 2 veterinary pulse oximeters (SDI Vet-Ox #4402 and Nellcor N-20V) were compared in 6 isoflurane-anesthetized dogs. Simultaneous readings Of S_p0₂were recorded from 2 sites (toe and ear) over a range of inspired oxygen concentrations (15-100%), and compared to directly measured S_aO₂ readings. Greater variability of readings was obtained from the Vet-Ox, which failed to give readings 25% of the time. The bias (mean S_aO₂-S_p0₂) and precision (SD of bias) were calculated from the data for each oximeter. For the Vet-Ox, bias (precision) from the toe was +4.O (5.2) and from the ear +1.7 (2.2). The bias (precision) for N-20V readings from the toe was +1.6 (1.5) and from the ear +0.7 (1.5). Generally, both oximeters tended to underestimate S_aO₂; however, both overestimated at the lowest P_a0₂ values. Pearscn cowelation coeefficients were 0.81 for the Vet-Ox and 0.94 for the N-20V for the combined data, including value from probes placed on the toe and ear at all inspired oxygen concentrations. In the two locatiom from which readings were obtained, the 2 units performed quite differently.     

Effect of medetomidine and its antagonism with atipamezole on stress-related hormones, metabolites, physiologic responses, sedation, and mechanical threshold in goats

OBJECTIVE: To evaluate the effects of medetomidine and its antagonism with atipamezole in goats. STUDY DESIGN: Prospective randomized crossover study with 1 week between treatments. ANIMALS: Six healthy 3-year-old neutered goats (three male and three female) weighing 39.1-90.9 kg (60.0 +/- 18 kg, mean +/- SD). METHODS: Goats were given medetomidine (20 microg kg(-1), IV) followed, 25 minutes later, by either atipamezole (100 microg kg(-1), IV) or saline. Heart and respiratory rate, rectal temperature, indirect blood pressure, and mechanical threshold were measured, and sedation and posture were scored and blood samples obtained to measure epinephrine, norepinephrine, free fatty acids, glucose, and cortisol concentrations at baseline (immediately before medetomidine), 5 and 25 minutes after medetomidine administration, and at 5, 30, 60, and 120 minutes after the administration of antagonist or saline. Parametric and nonparametric tests were used to evaluate data; p < 0.05 was considered significant. RESULTS: Medetomidine decreased body temperature, heart rate, and respiratory rate and increased mean arterial blood pressure, cortisol, and glucose. Recumbency occurred 89 +/- 50 seconds after medetomidine administration. All goats were standing 86 +/- 24 seconds after atipamezole administration whereas all goats administered saline were sedate and recumbent at 2 hours. Tolerance to compression of the withers and metacarpus increased with medetomidine. From 5 to 120 minutes after saline or atipamezole administration, there were differences in body temperature, glucose, and cortisol but none in heart rate or blood pressure. Three of the six goats receiving saline developed bloat; five of six urinated. After atipamezole, four of six goats developed piloerection and all goats were agitated and vocalized. CONCLUSION: At the doses used, atipamezole antagonized the effects of medetomidine on recumbency, sedation, mechanical threshold, and the increase in glucose. Atipamezole increased the rate of return of cortisol toward baseline, and prevented further decline in rectal body temperature. CLINICAL RELEVANCE: Atipamezole may be used to antagonize some, but not all effects of medetomidine.