OBJECTIVE To determine the anabolic and lipolytic effects of a low dosage of clenbuterol administered orally in working and nonworking equids. ANIMALS 8 nonworking horses and 47 polo ponies in active training. PROCEDURES Each polo pony continued training and received either clenbuterol (0.8 μg/kg) or an equal volume of corn syrup (placebo) orally twice daily for 21 days, and then was evaluated for another 21-day period. Nonworking horses received clenbuterol or placebo at the same dosage for 21 days in a crossover trial (2 treatments/horse). For working and nonworking horses, percentage body fat (PBF) was estimated before treatment and then 2 and 3 times/wk, respectively. Body weight was measured at intervals. RESULTS Full data sets were not available for 8 working horses. For working horses, a significant treatment effect of clenbuterol was detected by day 3 and continued through the last day of treatment; at day 21, the mean change in PBF from baseline following clenbuterol or placebo treatment was −0.80% (representing a 12% decrease in PBF) and −0.32%, respectively. By day 32 through 42 (without treatment), PBF change did not differ between groups. When treated with clenbuterol, the nonworking horses had a similar mean change in PBF from baseline from day 6 onward, which peaked at −0.75% on day 18 (an 8% decrease in PBF). Time and treatment had no significant effect on body weight in either experiment. CONCLUSIONS AND CLINICAL RELEVANCE Among the study equids, long-term low-dose clenbuterol administration resulted in significant decreases in body fat with no loss in body weight.

OBJECTIVE To characterize the postprandial nutrient profiles of exercise-conditioned dogs fed a supplemental carbohydrate and protein bar with or without astaxanthin from Haematococcus pluvialis immediately after exercise. ANIMALS 34 exercise-conditioned adult Husky-Pointer dogs. PROCEDURES The study had 2 phases. During phase 1, postprandial plasma glucose concentration was determined for dogs fed a bar containing 25% protein and 18.5% or 37.4% maltodextrin plus dextrin (rapidly digestible carbohydrate; RDC), or dry kibble (30% protein and 0% RDC) immediately after exercise. During phase 2, dogs were exercised for 3 days and fed a bar (25% protein and 37.4% RDC) with (CPA; n = 8) or without (CP; 8) astaxanthin or no bar (control; 8) immediately after exercise. Pre- and postexercise concentrations of plasma biochemical analytes and serum amino acids were determined on days 1 and 3. RESULTS Phase 1 postexercise glucose concentration was increased when dogs were provided the 37.4% RDC bar, but not 0% or 18.5% RDC. On day 3 of phase 2, the CPA group had the highest pre-exercise triglyceride concentration and significantly less decline in postexercise glucose concentration than did the CP and control groups. Mean glucose concentration for the CP and CPA groups was significantly higher than that for the control group between 15 and 60 minutes after bar consumption. Compared to immediately after exercise, branched-chain amino acid, tryptophan, leucine, and threonine concentrations 15 minutes after exercise were significantly higher for the CP and CPA groups, but were lower for the control group. CONCLUSIONS AND CLINICAL RELEVANCE Dogs fed a bar with 37.4% RDCs and 25% protein immediately after exercise had increased blood nutrient concentrations for glycogen and protein synthesis, compared with control dogs.

OBJECTIVE To assess the urinary protein-to-creatinine ratio (UPCR) of healthy sexually intact male dogs and to compare the UPCR of these dogs before and after castration. ANIMALS 19 client- or shelter-owned healthy adult sexually intact male dogs. PROCEDURES Physical, hematologic, and biochemical examinations and urinalysis (including calculation of the UPCR) were performed on each dog. Dogs were then castrated, and physical examination and urinalysis (including calculation of the UPCR) were performed again at least 15 days after castration. RESULTS A dipstick test yielded positive results for protein in the urine of 10 sexually intact male dogs, but the UPCR was < 0.5 for all sexually intact male dogs. Mean UPCR for sexually intact male dogs was 0.12 (range, 0.10 to 0.32). The UPCR was < 0.2 for all castrated dogs, except for 1. Mean UPCR for all castrated dogs was 0.08 (range, 0.05 to 0.69). There was a significant difference between mean UPCR before and after castration. CONCLUSIONS AND CLINICAL RELEVANCE In this study, pathological proteinuria was not detected in sexually intact male dogs. Positive results for a urine dipstick test should be interpreted with caution in sexually intact male dogs and should be confirmed by assessment of the UPCR. An increased UPCR in sexually intact male dogs may be considered abnormal.

OBJECTIVE To determine the scan delay for use in performing cardiac CT angiography in dogs. ANIMALS 4 clinically normal adult Beagles. PROCEDURES In a crossover study, 12 formulations of iohexol solutions differing in iodine dose (300, 400, and 800 mg/kg) and concentration (undiluted and diluted 1:1, 1:2, and 1:3 with saline [0.9% NaCl] solution) were administered IV to each dog. Dynamic CT angiography was performed to evaluate enhancement characteristics of each formulation, with the region of interest set over the aorta. Time-attenuation curves (TACs) were obtained and analyzed. RESULTS Peak arc–type TACs were obtained after administration of all undiluted formulations. Curve shape changed from peak arc type to plateau type as the total volume of the contrast solution (ie, dilution) increased. Prolonged peaks characteristic of plateau-type TACs suggested that a sufficient period of homogeneous attenuation could be achieved for CT scanning with administration of higher iohexol dilutions (1:2 or 1:3) containing higher iodine doses (400 or 800 mg/kg). In particular, attenuation values for plateau-type TACs remained between 200 and 300 Hounsfield units for > 16 seconds after the plateau endpoint was reached for 1:2 and 1:3 dilutions containing an iodine dose of 800 mg/kg. Scan delays of 13 to 17 seconds were computed for those 2 formulations. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that for clinically normal dogs, a scan delay of 13 to 17 seconds could be used to perform cardiac CT angiography with iohexol solutions containing an iodine dose of 800 mg/kg at dilutions of 1:2 or 1:3.

OBJECTIVE To determine effects of increasing plasma fentanyl concentrations on the minimum alveolar concentration (MAC) of isoflurane in rabbits. ANIMALS 6 adult female New Zealand White rabbits (Oryctolagus cuniculus). PROCEDURES Rabbits were anesthetized with isoflurane in oxygen; ventilation was controlled and body temperature maintained between 38.5° and 39.5°C. Fentanyl was administered IV by use of a computer-controlled infusion system to achieve 6 target plasma concentrations. Isoflurane MAC was determined in duplicate by use of the bracketing technique with a supramaximal electrical stimulus. Blood samples were collected for measurement of plasma fentanyl concentration at each MAC determination. The MAC values were analyzed with a repeated-measures ANOVA followed by Holm-Sidak pairwise comparisons. RESULTS Mean ± SD plasma fentanyl concentrations were 0 ± 0 ng/mL (baseline), 1.2 ± 0.1 ng/mL, 2.2 ± 0.3 ng/mL, 4.4 ± 0.4 ng/mL, 9.2 ± 0.4 ng/mL, 17.5 ± 2.6 ng/mL, and 36.8 ± 2.4 ng/mL. Corresponding mean values for isoflurane MAC were 1.92 ± 0.16%, 1.80 ± 0.16%, 1.60 ± 0.23%, 1.46 ± 0.22%, 1.12 ± 0.19%, 0.89 ± 0.14%, and 0.70 ± 0.15%, respectively. Isoflurane MAC for plasma fentanyl concentrations ≥ 2.2 ng/mL differed significantly from the baseline value. In 3 rabbits, excessive spontaneous movement prevented MAC determination at the highest plasma fentanyl concentration. CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl reduced isoflurane MAC by approximately 60% in New Zealand White rabbits. Further studies will be needed to investigate the cardiorespiratory effects of isoflurane and fentanyl combinations in rabbits; however, fentanyl may prove to be a useful adjunct to inhalation anesthesia in this species.

OBJECTIVE To determine pharmacokinetics of butorphanol delivered via osmotic pumps in common peafowl (Pavo cristatus) as a method for analgesic administration to avian species. ANIMALS 14 healthy adult male common peafowl. PROCEDURES A preliminary experiment was conducted with 2 birds to establish time point and concentration requirements. Then, the remaining 12 birds were anesthetized, and 2 osmotic pumps containing butorphanol (volume, 2 mL; mean dosage, 247 μg/kg/h) were implanted subcutaneously in each bird for 7 days prior to removal. Blood samples were collected before pump implantation (time 0); 3, 6, 12, 24, 48, 72, 96, 120, 144, and 168 hours after pump implantation; and 3 and 6 hours after pump removal. Plasma butorphanol concentrations were measured via liquid chromatography–mass spectrometry. RESULTS Plasma concentrations peaked (mean, 106.4 μg/L; range, 61.8 to 133.0 μg/L) at a mean of 39.0 hours, with no evidence of sedation in any bird. After pump removal, butorphanol was rapidly eliminated (half-life, 1.45 hours; range, 1.31 to 1.64 hours; n = 5). Mean clearance per fraction of dose absorbed was 2.89 L/kg/h (range, 2.00 to 5.55 L/kg/h). Mean amount of time the plasma butorphanol concentration was ≥ 60 μg/L was 85.6 hours (range, 3.5 to 155.3 hours). CONCLUSIONS AND CLINICAL RELEVANCE Plasma concentrations of butorphanol in common peafowl were maintained at or above reported efficacious analgesic concentrations. This study established a method for administering analgesics to avian patients without the need for frequent handling or injections. Use of these osmotic pumps may provide options for avian analgesia.

OBJECTIVE To validate primer sets for use in reverse transcription quantitative PCR assays to measure gene expression of cytosolic phospholipase A2 (cPLA2) and microsomal prostaglandin E2 synthase 1 (mPGES1) in equine mononuclear cells and determine the effects of firocoxib, a selective cyclooxygenase 2 (COX-2) inhibitor, on COX-2, cPLA2, and mPGES1 gene expression following incubation of mononuclear cells with lipopolysaccharide (LPS). ANIMALS 8 healthy adult horses. PROCEDURES Peripheral blood mononuclear cells were isolated by density gradient centrifugation and incubated at 37°C with medium alone, firocoxib (100 ng/mL), LPS (1 ng/mL or 1 μg/mL), or combinations of firocoxib and both LPS concentrations. After 4 hours, supernatants were collected and tested for prostaglandin E2 (PGE2) concentration with an enzyme inhibition assay, and gene expression in cell lysates was measured with PCR assays. RESULTS Primer pairs for cPLA2 and mPGES1 yielded single products on dissociation curve analyses, with mean assay efficiencies of 102% and 100%, respectively. Incubation with firocoxib and LPS significantly decreased PGE2 supernatant concentrations and significantly reduced COX-2 and mPGES1 gene expression, compared with values following incubation with LPS alone. CONCLUSIONS AND CLINICAL RELEVANCE Primer sets for mPGES1 and cPLA2 gene expression in equine mononuclear cells were successfully validated. Firocoxib significantly decreased LPS-induced COX-2 and mPGES1 expression, suggesting that it may be useful in the control of diseases in which expression of these genes is upregulated.

OBJECTIVE To evaluate pharmacokinetics, recovery times, and recovery quality in horses anesthetized with 1.2 times the minimum alveolar concentration of sevoflurane or desflurane. ANIMALS 6 healthy adult horses. PROCEDURES Anesthesia was maintained with sevoflurane or desflurane for 2 hours at 1.2 times the minimum alveolar concentration. Horses recovered without assistance. During recovery, end-tidal gas samples were collected until horses spontaneously moved. Anesthetic concentrations were measured by use of gas chromatography. After a 1-week washout period, horses were anesthetized with the other inhalation agent. Video recordings of anesthetic recovery were evaluated for recovery quality on the basis of a visual analogue scale by investigators who were unaware of the anesthetic administered. Anesthetic washout curves were fit to a 2-compartment kinetic model with multivariate nonlinear regression. Normally distributed interval data were analyzed by means of paired Student t tests; ordinal or nonnormally distributed data were analyzed by means of Wilcoxon signed rank tests. RESULTS Horses recovered from both anesthetics without major injuries. Results for subjective recovery evaluations did not differ between anesthetics. Area under the elimination curve was significantly smaller and time to standing recovery was significantly less for desflurane than for sevoflurane, although distribution and elimination constants did not differ significantly between anesthetics. CONCLUSIONS AND CLINICAL RELEVANCE Differences in area under elimination the curve between anesthetics indicated more rapid clearance for desflurane than for sevoflurane in horses, as predicted by anesthetic blood solubility differences in this species. More rapid elimination kinetics was associated with faster recovery times, but no association with improved subjective recovery quality was detected.

OBJECTIVE To develop equations for prediction of total body water (TBW) content in unsedated dogs by combining impedance (resistance and reactance) and morphological variables and to compare the results of those equations with TBW content determined by deuterium dilution (TBWd). ANIMALS 26 healthy adult Beagles. PROCEDURES TBW content was determined directly by deuterium dilution and indirectly with equations developed from measurements obtained by use of a portable bioelectric impedance device and morphological variables including body length, height, weight, and thoracic and abdominal circumferences. RESULTS Impedance and morphological data from 16 of the 26 dogs were used to determine coefficients for the following 2 equations: TBW1 = −0.019 (BL2/R) + −0.199 (RC + AC) + 0.996W + 0.081H + 12.31; and TBW2 = 0.048 (BL2/R) + −0.144 (RC + AC) + 0.777W + 0.066H + 0.031X + 7.47, where AC is abdominal circumference, H is height, BL is body length, R is resistance, RC is rib cage circumference, W is body weight, and × is reactance. Results for TBW1 (R21 = 0.843) and TBW2 (R22 = 0.816) were highly correlated with the TBWd. When the equations were validated with data from the remaining 10 dogs, the respective mean differences between TBWd and TBW1 and TBW2 were 0.17 and 0.11 L, which equated to a nonsignificant underestimation of TBW content by 2.4% and 1.6%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that impedance and morphological data can be used to accurately estimate TBW content in adult Beagles. This method of estimating TBW content is less expensive and easier to perform than is measurement of TBWd, making it appealing for daily use in veterinary practice.

OBJECTIVE To establish the minimum alveolar concentration (MAC) of desflurane and evaluate the effects of 2 opioids on MAC in sheep. ANIMALS 8 adult nulliparous mixed-breed sheep. PROCEDURES A randomized crossover design was used. Each sheep was evaluated individually on 2 occasions (to allow assessment of the effects of each of 2 opioids), separated by a minimum of 10 days. On each occasion, sheep were anesthetized with desflurane in 100% oxygen, MAC of desflurane was determined, oxymorphone (0.05 mg/kg) or hydromorphone (0.10 mg/kg) was administered IV, and MAC was redetermined. Physiologic variables and arterial blood gas and electrolyte concentrations were measured at baseline (before MAC determination, with end-tidal desflurane concentration maintained at 10%) and each time MAC was determined. Timing of various stages of anesthesia was recorded for both occasions. RESULTS Mean ± SEM MAC of desflurane was 8.6 ± 0.2%. Oxymorphone or hydromorphone administration resulted in significantly lower MAC (7.6 ± 0.4% and 7.9 ± 0.2%, respectively). Cardiac output at MAC determination for desflurane alone and for desflurane with opioid administration was higher than that at baseline. No difference was identified among hematologic values at any point. Effects of oxymorphone and hydromorphone on durations of various stages of anesthesia did not differ significantly. CONCLUSIONS AND CLINICAL RELEVANCE MAC of desflurane in nulliparous adult sheep was established. Intravenous administration of oxymorphone or hydromorphone led to a decrease in MAC; however, the clinical importance of that decrease was minor relative to the effect in other species.