OBJECTIVE To evaluate thermal antinociceptive effects and pharmacokinetics of buprenorphine hydrochloride after IM administration to cockatiels (Nymphicus hollandicus).
ANIMALS 16 adult (≥ 2 years old) cockatiels (8 males and 8 females).
PROCEDURES Buprenorphine hydrochloride (0.3 mg/mL) at each of 3 doses (0.6, 1.2, and 1.8 mg/kg) and saline (0.9% NaCl) solution (control treatment) were administered IM to birds in a randomized within-subject complete crossover study. Foot withdrawal response to a thermal stimulus was determined before (baseline) and 0.5, 1.5, 3, and 6 hours after treatment administration. Agitation-sedation scores were also determined. For the pharmacokinetic analysis, buprenorphine (0.6 mg/kg) was administered IM to 12 of the birds, and blood samples were collected at 9 time points ranging from 5 minutes to 9 hours after drug administration. Samples were analyzed with liquid chromatography–mass spectrometry. Pharmacokinetic parameters were calculated with commercial software.
RESULTS Buprenorphine at 0.6, 1.2, and 1.8 mg/kg did not significantly change the thermal foot withdrawal response, compared with the response for the control treatment. No significant change in agitation-sedation scores was detected between all doses of buprenorphine and the control treatment. Plasma buprenorphine concentrations were > 1 ng/mL in all 4 birds evaluated at 9 hours.
CONCLUSIONS AND CLINICAL RELEVANCE Buprenorphine at the doses evaluated did not significantly change the thermal nociceptive threshold for cockatiels or cause sedative or agitative effects. Additional studies with other pain assessments and drug doses are needed to evaluate the analgesic and adverse effects of buprenorphine in cockatiels and other avian species.
Objective—To assess the agreement and reliability of cardiac measurements obtained with 3 echocardiographic techniques in anesthetized red-tailed hawks (Buteo jamaicensis).
Animals—10 red-tailed hawks.
Procedures—Transcoelomic, contrast transcoelomic, and transesophageal echocardiographic evaluations of the hawks were performed, and cineloops of imaging planes were recorded. Three observers performed echocardiographic measurements of cardiac variables 3 times on 3 days. The order in which hawks were assessed and echocardiographic techniques were used was randomized. Results were analyzed with linear mixed modeling, agreement was assessed with intraclass correlation coefficients, and variation was estimated with coefficients of variation.
Results—Significant differences were evident among the 3 echocardiographic methods for most measurements, and the agreement among findings was generally low. Interobserver agreement was generally low to medium. Intraobserver agreement was generally medium to high. Overall, better agreement was achieved for the left ventricular measurements and for the transesophageal approach than for other measurements and techniques.
Conclusions and Clinical Relevance—Echocardiographic measurements in hawks were not reliable, except when the left ventricle was measured by the same observer. Furthermore, cardiac morphometric measurements may not be clinically important. When measurements are required, one needs to consider that follow-up measurements should be performed by the same echocardiographer and should show at least a 20% difference from initial measurements to be confident that any difference is genuine.
To evaluate a carrageenan-induced inflammatory model in the cockatiel (Nymphicus hollandicus) using weight-bearing load, rotational perch locomotion, thermal threshold withdrawal, and footpad dimensions.
16 adult cockatiels (8 males and 8 females).
Cockatiels were randomly assigned into 2 groups as either treatment (carrageenan injection; n = 8) or control (handling only; 8). Treatment of cockatiels involved unilateral subcutaneous injection of 0.05 mL of 1% lambda carrageenan solution into the left footpad. Control birds were handled in a similar manner without an injection. Following baseline measurements and treatment or control procedures, posttreatment measurements at multiple time points involving weight-bearing perch load (for up to 336 hours), locomotive abilities when placed on a rotating perch (for up to 96 hours), thermal withdrawal threshold (for the 24- to 30-hour period), and both vertical and horizontal left footpad size and degree of swelling (for up to 84 days) were obtained.
Treatment cockatiels had a significant decrease in left foot weight-bearing load and increase in left footpad dimensions and swelling grade over time compared to control cockatiels. Rotational perch locomotion and thermal withdrawal threshold, conversely, did not differ significantly between groups. Cockatiels injected with carrageenan returned to normal weight-bearing within 2 weeks; however, left footpad dimensions did not return to baseline.
Carrageenan footpad injection prompts a measurable and grossly visible inflammatory response in the cockatiel. Additionally, it induces alterations in weight-bearing distribution in injected birds. This model provides a method to evaluate inflammation and lameness in small psittacine species.
To compare stress markers, gastrointestinal motility, and behavioral indicators of pain between guinea pigs undergoing pneumoperitoneum with carbon dioxide (CO2) and control guinea pigs.
Fourteen 4- to 5-month-old intact female Hartley guinea pigs.
Guinea pigs were randomized to receive insufflation or serve as controls (anesthesia and abdominal catheter placement without insufflation), with 7 animals/group. Insufflated animals underwent 6 mm Hg of CO2 pneumoperitoneum for 30 minutes. Afterward, results for vital signs, blood glucose, fecal cortisol, appetite, fecal output, and behaviors (via video recording) were compared between the 2 groups.
There was no difference between groups and over time for body temperature, heart rate, fecal output in grams, pellets consumed, blood glucose, and fecal cortisol. Guinea pigs that underwent insufflation had significantly more fecal pellets at 36 hours after the procedure. Several behaviors were expressed similarly between groups and over time, such as body turns, incomplete movement, rearing, lying down, drinking, and hiding. Coprophagy occurred less often in the insufflated versus noninsufflated group at 12 h postprocedure but was similar between groups at other time points. At 60 hours after the procedure, insufflated animals spent less time squinting compared to noninsufflated animals. Other behaviors were differentially expressed over time but not between treatments.
Overall, there were no major differences in appetite, stress markers, and behaviors between insufflated and control guinea pigs. CO2 insufflation did not appear to cause undue pain or stress in guinea pigs and may be a reasonable technique to use during laparoscopy.
To evaluate pneumoperitoneal volumes (laparoscopic working space) in guinea pigs (Cavia porcellus) undergoing pneumoperitoneum via carbon dioxide insufflation at different intra-abdominal pressures (IAPs) (4, 6, and 8 mm Hg) and recumbencies (dorsal, right lateral, and left lateral).
Six 3- to 4-month-old sexually intact female Hartley guinea pigs.
Guinea pigs were anesthetized, intubated, and had an abdominal insufflation catheter placed. A baseline abdominal CT scan was performed. Guinea pigs underwent insufflation, with each IAP given in a random order for 10 to 15 minutes with a washout period of 5 minutes between pressures. Abdominal CT scans were acquired at each IAP and at each recumbency. Pneumoperitoneal volumes were calculated using software.
Increases in IAP increased working space significantly (P < .001). The 6- and 8-mm Hg pressures increased working space from 4 mm Hg by 7.3% and 19.8%, respectively. Recumbent positioning (P = .60) and body weight (P = .73) did not affect working space. Order of IAP had a significant (P = .006) effect on working space. One of the guinea pigs experienced oxygen desaturation and bradycardia at 6- and 8-mm Hg IAP.
Although an increased working space occurred at 6 and 8 mm Hg compared to 4 mm Hg, further research is needed concerning the cardiovascular effects of pneumoperitoneum in guinea pigs to determine whether those higher IAPs are safe in this species. An IAP of 6 mm Hg can be considered for laparoscopic cannula placement, followed by a lower IAP for laparoscopic procedures.
Procedures—16-slice CT scanning was used to measure the apparent diameter of the ascending aorta, abdominal aorta, pulmonary arteries, and brachiocephalic trunk. Before scanning, all birds underwent ECG and echocardiographic assessment and were considered free of detectable cardiovascular diseases. Each bird was anesthetized, and a precontrast helical CT scan was performed. Peak aortic enhancement was established with a test bolus technique via dynamic axial CT scan over a predetermined single slice. An additional bolus of contrast medium was then injected, and a helical CT-angiography scan was performed immediately afterward. Arterial diameter measurements were obtained by 2 observers via various windows before and after injection, and intra- and interobserver agreement was assessed.
Results—Reference limits were determined for arterial diameter measurements before and after contrast medium administration in pulmonary, mediastinal, and manual angiography windows. Ratios of vertebral body diameter to keel length were also calculated. Intraobserver agreement was high (concordance correlation coefficients ≥ 0.95); interobserver agreement was medium to high (intraclass correlation coefficients ≥ 0.65).
Conclusions and Clinical Relevance—CT-angiography was safe and is of potential diagnostic value in parrots. We recommend performing the angiography immediately after IV injection of 3 mL of iohexol/kg. Arterial diameter measurements at the described locations were reliable.
OBJECTIVE To determine pharmacokinetics of butorphanol tartrate incorporated into poloxamer 407 (P407) after SC administration to Hispaniolan Amazon parrots (Amazona ventralis).
ANIMALS 11 adult Hispaniolan Amazon parrots (6 males and 5 females; 11 to 27 years old).
PROCEDURES A sterile formulation of butorphanol in P407 (But-P407) 25% (percentage determined as [weight of P407/weight of diluent] × 100]) was created (8.3 mg/mL). Five preliminary experiments (2 birds/experiment) were performed to determine the ideal dose for this species. The formulation then was administered (12.5 mg/kg, SC) to 8 birds. Blood samples were collected before (time 0) and 0.08, 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration. Some birds were used more than once, with a washout period of ≥ 3 months between subsequent treatments. Butorphanol concentrations were quantitated by use of liquid chromatography-tandem mass spectrometry. Pharmacokinetic analysis was performed by use of noncompartmental analysis.
RESULTS Maximal plasma butorphanol concentration was reached at 1.31 hours. Plasma concentrations of butorphanol remained > 100 ng/mL for > 3 hours (all birds) or > 4 hours (5/8 birds) but < 8 hours (all birds). Half-life of the terminal slope was 3.41 hours. No adverse effects were detected.
CONCLUSIONS AND CLINICAL RELEVANCE Butorphanol was absorbed well from the But-P407 25% by Hispaniolan Amazon parrots, and absorption followed a pharmacokinetic profile compatible with a sustained-release drug. A dose of 12.5 mg/kg, SC, would theoretically provide analgesia for 4 to 8 hours. No adverse effects were detected. Studies on the pharmacodynamics of this formulation are necessary to confirm the degree and duration of analgesia.
OBJECTIVE To evaluate peripheral blood and abdominal fluid variables as predictors of intestinal surgical site failure in dogs with septic peritonitis following celiotomy and closed-suction abdominal drain (CSAD) placement.
DESIGN Prospective study.
ANIMALS 26 dogs with septic peritonitis that underwent celiotomy and CSAD placement.
PROCEDURES Abdominal fluid and blood samples were collected prior to surgery and daily thereafter until CSAD removal. Abdominal fluid was collected through the CSAD. Analysis of all samples included pH, PCO2, PO2, PCV, WBC count, and total solids, glucose, lactate, and electrolyte concentrations. Abdominal fluid samples also underwent cytologic evaluation and bacterial culture, and the volume of fluid removed through the drain was recorded daily. The blood-to-fluid glucose and lactate differences, fluid-to-blood lactate ratio and blood-to-fluid WBC and neutrophil ratios were determined daily. Dogs were categorized into 2 groups on the basis of whether they had an uneventful recovery (UR) or developed postoperative septic peritonitis (POSP).
RESULTS 23 dogs had a UR and 3 developed POSP. On the third day after surgery, the abdominal fluid WBC count was significantly lower and the blood-to-fluid WBC and neutrophil ratios were significantly higher for dogs in the POSP group, compared with those for dogs in the UR group. None of the other blood and abdominal fluid variables assessed differed significantly between the 2 groups.
CONCLUSIONS AND CLINICAL RELEVANCE Results failed to identify any objective predictive indicators for POSP in dogs with CSADs. Use of blood-to-fluid WBC and neutrophil ratios as predictive indicators for POSP requires further investigation.
First, butorphanol tartrate (5 mg/kg) or saline (0.9% NaCl) solution was administered IM to birds in a randomized complete crossover design. The temperature prompting a foot withdrawal response to a thermal stimulus (ie, the thermal threshold) was determined 30 minutes before (baseline) and at various points after treatment administration. Second, But-P407 (12.5 mg/kg) or P407 was administered SC in a similar crossover design. Thermal threshold was determined before and at various points after treatment administration. Third, But-P407 (12.5 mg/kg) or saline solution was administered SC and evaluated as in the second trial. Sedation was scored immediately before each time point in all 3 trials.
In the first trial, a significant increase in thermal threshold was noted 30 minutes after butorphanol tartrate (vs saline solution) administration. No sedation was noted. In the second and third trials, no significant difference was identified between results for But-P407 and those for either control treatment (saline solution or P407). Mild sedation was noted in the second trial following But-P407 administration.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested a small but significant thermal antinociceptive effect of butorphanol tartrate lasting between 30 minutes and 1.5 hours in orange-winged Amazon parrots. No antinociceptive effect of butorphanol tartrate was demonstrated when delivered in P407. Further research is needed to evaluate the potential analgesic effects of But-P407.
Objective—To assess the effects of dopamine and dobutamine on the blood pressure of isoflurane-anesthetized Hispaniolan Amazon parrots (Amazona ventralis).
Animals—8 Hispaniolan Amazon parrots.
Procedures—A randomized crossover study was conducted. Each bird was anesthetized (anesthesia maintained by administration of 2.5% isoflurane in oxygen) and received 3 doses of each drug during a treatment period of 20 min/dose. Treatments were constant rate infusions (CRIs) of dobutamine (5, 10, and 15 μg/kg/min) and dopamine (5, 7, and 10 μg/kg/min). Direct systolic, diastolic, and mean arterial pressure measurements, heart rate, esophageal temperature, and end-tidal partial pressure of CO2 were recorded throughout the treatment periods.
Results—Mean ± SD of the systolic, mean, and diastolic arterial blood pressures at time 0 (initiation of a CRI) were 132.9 ± 22.1 mm Hg, 116.9 ± 20.5 mm Hg, and 101.9 ± 22.0 mm Hg, respectively. Dopamine resulted in significantly higher values than did dobutamine for the measured variables, except for end-tidal partial pressure of CO2. Post hoc multiple comparisons revealed that the changes in arterial blood pressure were significantly different 4 to 7 minutes after initiation of a CRI. Overall, dopamine at rates of 7 and 10 μg/kg/min and dobutamine at a rate of 15 μg/kg/min caused the greatest increases in arterial blood pressure.
Conclusions and Clinical Relevance—Dobutamine CRI at 5, 10, and 15 μg/kg/min and dopamine CRI at 5, 7, and 10 μg/kg/min may be useful in correcting severe hypotension in Hispaniolan Amazon parrots caused by anesthesia maintained with 2.5% isoflurane.