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- Author or Editor: Rebecca A. Johnson x
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Abstract
Objective
To compare mask anesthesia induction and recovery characteristics between 2 inhalant anesthetic agents: isoflurane and sevoflurane.
Animals
16 clinically normal, young adult Beagles.
Procedure
Using a cross-over design, dogs were randomly selected to receive sevoflurane or isoflurane via a face mask and a circle anesthetic system. Vaporizer setting concentrations were increased in step-wise, equal minimum alveolar concentrations (MAC) for each anesthetic until the vaporizer setting of 2.6% for isoflurane or 4.8% for sevoflurane (2 MAC) was reached. Concentration was kept constant until the dog had a negative tail clamp response and was intubated. End-tidal concentration was maintained at 1.8 to 2.0% or 3.3 to 3.8% for isoflurane or sevoflurane, respectively (1.4 to 1.6 MAC) for 30 minutes. Dogs were allowed to recover with only tail clamp stimulation until a positive response was obtained. Extubation was performed when a spontaneous swallow reflex was observed. Dogs were allowed to achieve sternal recumbency and stand unassisted without further stimulation.
Results
Sevoflurane induction resulted in shorter time to loss of palpebral reflex, negative tail clamp response, and time to tracheal intubation, and was of better quality than isoflurane induction. Both anesthetics were associated with rapid and smooth recovery.
Conclusions
Sevoflurane mask induction is faster and of better quality, compared with isoflurane, in adult dogs. Recovery time and quality are comparable.
Clinical Relevance
On the basis of these results, sevoflurane is a suitable inhalant anesthetic for mask induction and recovery in adult dogs and appears to have some advantages over isoflurane, including faster and smoother mask induction. (Am J Vet Res 1998;59:478–481)
Abstract
Objective
To determine the relation between epidural injectate volume (ml/kg of body weight) and its craniad migration in calves and pigs.
Animals
23 neonatal calves and 26 feeder pigs.
Procedure
Animals were randomly assigned to receive different volumes of new methylene blue (NMB, 1.2 mg/ml in 0.9% saline solution). Injections were made into the sacrococcygeal intervertebral space in calves and the lumbosacral intervertebral space in pigs, immediately after euthanasia. Sagittal sections of the spine were made at necropsy, and craniad migration of NMB was determined and rounded to the nearest intervertebral space.
Results
In calves treated with 0.05, 0.1, or 0.15 ml of NMB/kg, mean ± SEM number of stained spinal segments was 5 ± 0.3, 8 ± 0.6, and 8 ± 0.6, respectively. Craniad migration of NMB was significantly greater for 0.15 and 0.1 ml/kg volumes versus 0.05 ml/kg. In pigs treated with 0.05, 0.1, 0.2, or 0.3 ml of NMB/kg, mean number of stained spinal segments was 8 ± 1.1, 8 ± 0.9, 10 ± 1.2, and 18 ± 2.0. Craniad dye migration was significantly greater in the 0.3 ml/kg group versus the 3 lower volume groups. Linear regression performed on both sets of data after logarithmic transformation of spaces migrated to correct for non-normality was significant (P < 0.05), and R 2 values of 0.49 and 0.55 were obtained for calves and pigs, respectively.
Conclusions
There is a significant correlation between volume (ml/kg) of NMB injected in the epidural space and its craniad migration in calves and pigs.
Clinical Relevance
Results provide a basis for determination of volume of injectate to be given to reach a minimal desired level and should be a useful baseline for future investigations of epidural drug administration. (Am J Vet Res 1997;58:786–790)
Abstract
OBJECTIVE To quantify nausea and sedation scores, gastric emptying time, and gastrointestinal transit time after IV administration of a lidocaine hydrochloride bolus followed by a constant rate infusion (CRI) in clinically normal dogs.
ANIMALS 6 Beagles.
PROCEDURES In a crossover study, dogs were fed thirty 1.5-mm barium-impregnated spheres (BIPS) and received a saline (0.9% NaCl) solution bolus (0.05 mL/kg) IV (time 0) followed by a CRI at 10 mL/h, a lidocaine bolus (1 mg/kg) IV followed by a CRI at 25 μg/kg/min, or a lidocaine bolus (1 mg/kg) IV followed by a CRI at 50 μg/kg/min; CRIs were for 12 hours. Nausea and sedation scores were assessed and abdominal radiographs obtained immediately after feeding of BIPS and every hour for 12 hours and again 16 hours after CRI start. Percentage of BIPSs in the small and large intestines, gastric emptying time, and gastrointestinal transit time were assessed.
RESULTS Gastric emptying time did not differ significantly among treatments. Significantly more BIPS were in the large intestine 4 to 7 hours after treatment start for the 50-μg/kg/min treatment than for the other 2 treatments. Six hours after treatment start, significantly more BIPS were in the large intestine for the 25-μg/kg/min treatment than for the saline solution treatment. Higher sedation and nausea scores were associated with the 50-μg/kg/min CRI.
CONCLUSIONS AND CLINICAL RELEVANCE In clinically normal dogs, lidocaine CRI did not significantly affect gastric emptying. However, gastrointestinal transit time was mildly decreased and sedation and nausea scores increased in dogs administered a lidocaine CRI at clinically used doses.
Abstract
OBJECTIVE To evaluate effects of high-concentration buprenorphine (HCB) on self-injurious behavior, food intake, fecal output, and thermal withdrawal latencies in healthy rats.
ANIMALS 8 Sprague-Dawley rats.
PROCEDURES Rats received 4 SC treatments (HCB at 0.075, 0.15, or 0.30 mg/kg [HCB0.075, HCB0.15, and HCB0.30, respectively] or 5% dextrose solution [0.20 mL/kg]) in a randomized, crossover-design study. Self-injurious behavior was assessed for 8 hours after injection. Food intake and fecal output were assessed for predetermined periods before and after treatment and separated into 12-hour light and dark periods for further analysis. Withdrawal latencies were assessed before (time 0) and at predetermined times after injection. Data were compared among treatments and time points.
RESULTS Self-injurious behavior was observed up to 8 hours after injection for all HCB, but not dextrose, treatments. Preinjection food intake and fecal output amounts were similar among groups and higher during the dark period than during the light period. Food intake after all HCB treatments was higher during the light period and lower during the dark period, compared with preinjection results for the same treatments and with postinjection results for dextrose administration. Light-period fecal output was lower after HCB0.15 and HCB0.30 administration, compared with preinjection values for the same treatments and postinjection values for dextrose administration. Percentage change in withdrawal latency was significantly higher than that at time 0 (ie, 0%) for only 1 treatment (HCB0.30) at 1 time point (1 hour after injection).
CONCLUSIONS AND CLINICAL RELEVANCE Although HCB0.30 produced a degree of thermal hypoalgesia in healthy rats, self-injurious behavior and alterations in food intake and fecal output were detected, potentially affecting clinical utility of the treatment.
Abstract
OBJECTIVE To assess effects of buprenorphine hydrochloride (BH), sustained-release buprenorphine (SRB), and high-concentration buprenorphine (HCB) formulations in healthy rats.
ANIMALS 8 Sprague-Dawley rats.
PROCEDURES In a crossover-design study, rats received BH (0.05 mg/kg), SRB (1.2 mg/kg), HCB (0.30 mg/kg), or 5% dextrose solution (0.2 mL/kg), SC, once. Self-injurious behavior and thermal sensitivity (hind limb withdrawal latencies) were assessed prior to injection (time 0) and 1, 4, 8, 12, and 24 hours after injection. Food intake, kaolin intake, and fecal output were measured over 12-hour light and dark periods before and after each treatment. Values were compared among treatments and time points.
RESULTS Self-injurious behavior was detected with all buprenorphine treatments; scores were greater at all time points during the 12 hours after HCB and 24 hours after SRB administration than at time 0. Percentage change in hind limb withdrawal latencies from time 0 was higher with BH and HCB 1 hour after injection than at other time points. Postinjection light-period food intake was higher (BH and HCB) and dark-period food intake was lower (BH, HCB, and SRB), compared with preinjection values for the same treatments. For SRB, postinjection light-period kaolin intake was greater than the preinjection value, and postinjection light- and dark-period kaolin intake was greater than that for other treatments.
CONCLUSIONS AND CLINICAL RELEVANCE Hypoalgesic effects were briefly observed after administration of BH or HCB in healthy rats; adverse effects were detected in some rats with all buprenorphine formulations. Studies comparing effects of BH, SRB, and HCB in rats undergoing surgery or other noxious stimuli are indicated to determine clinical benefits in this species.
Abstract
OBJECTIVE
To investigate thermoregulation, thermal antinociception, food/kaolin intake, fecal output, and behavior following long-acting buprenorphine preparations in rats.
ANIMALS
8 adult male rats (Rattus norvegicus) were administered long-acting SC buprenorphine (SB; 0.65 mg/kg), transdermal buprenorphine (TB; 10 mg/kg), and controls in a randomized, cross-over design.
METHODS
Body temperature, self-injury, sedation, food/kaolin intake, fecal output, and thermal withdrawal latencies were measured 1, 4, 8, 12, 24, 48, and 72 hours posttreatment. Data analysis was performed with mixed linear models.
RESULTS
Self-injury was present between 1 and 12 hours and 4 and 12 hours following TB and SB, respectively; sedation was associated with TB at 12 to 24 hours. Withdrawal latencies were longer in both TB and SB groups than in the control group. Food intake decreased with time in all groups but was significantly lower 24 to 48 hours after TB and 24 to 72 hours after SB versus controls. Kaolin intake decreased from baseline 48 to 72 hours in the control group. Fecal output decreased from baseline 24 to 72 hours in all groups but was significantly lower than controls 24 hours following TB and 24 to 48 hours in SB. Body temperature increased from baseline at 1 hour, 1 to 12 hours, and 1 to 24 hours in the control, TB, and SB groups, respectively, and was significantly higher than the control group 1 to 72 hours following TB and 4 to 24 hours after SB. Transdermal buprenorphine and SB in normal rats produced antinociception, self-injurious behavior, hyperthermia, and decreased food/fecal output.
CLINICAL RELEVANCE
Although these buprenorphine preparations may produce antinociception, untoward effects such as hyperthermia, self-injurious behavior, and reduced food intake/fecal output may be seen.
Abstract
Objective—To elucidate the ultrastructural details of calcium oxalate-containing urinary calculi from dogs.
Sample Population—38 specimens selected from a collection of 8,297 oxalate-containing urinary calculi from dogs: 22 specimens composed of calcium oxalate (calcium oxalate monohydrate [COM], calcium oxalate dihydrate [COD], or COM and COD) and 16 specimens composed of calcium oxalate with amorphous calcium phosphate.
Procedure—Analyses of specimens included use of plain, reflected, and polarized light microscopy, X-ray diffractometry, scanning electron microscopy (SEM) with backscattered electron (BSE) imagery, and electron microprobe analysis.
Results—Four texture types were observed in calcium oxalate calculi; 4 texture types of calcium oxalatecalcium phosphate-mixed calculi were recognized. Texture types were delineated through differences in calcium oxalate crystal sizes, which were affected by urine supersaturation and abundance of crystal nucleation sites. Segregation of calcium oxalate from calcium phosphate indicated they do not precipitate under the same conditions. Deposition of calcium phosphate between calcium oxalate crystals decreased the volume of pore spaces within calculi. Porosity was observed along boundaries between COM and COD. Minute pores increased the surface area of calculi exposed to urine, and this increase in liquid-solid interface promotes interaction of crystals with the surrounding urine.
Conclusions and Clinical Relevance—Calcium oxalate urolithiasis is of major concern, because it is often a recurrent disease among dogs, principally treated by surgical removal of calculi, with few effective dissolution strategies. Understanding the ultrastructure and mineralogic content of calcium oxalate and its association with amorphous calcium phosphate is a step toward the solution of this increasingly important medical problem. (Am J Vet Res 2001;62:237–247)
Abstract
Objective
To elucidate the ultrastructural details of struvite-containing urinary calculi from dogs.
Sample Population
38 specimens were selected from a collection of approximately 13,000 canine urinary calculi: 18 of these were composed entirely of struvite, and 20 consisted of struvite and calcium phosphate (apatite).
Procedure
Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron microprobe analysis.
Results
4 textural types were recognized among struvite calculi, and 4 textural types of struvite-apatite calculi were described. Evidences of calculus dissolution were described from 4 calculi studied.
Conclusions
The presence of small, well interconnected primary pores in struvite-containing urinary calculi from dogs appears to be a significant factor in determining the possible interaction of calculi with changes in the urine composition. The progress of dissolution from the calculus surface to the calculus interior appears to be largely affected by the primary porosity originally present between crystals forming the calculus framework. Apatite was observed to be more resistant to dissolution than struvite.
Clinical Relevance
The prevalence of fine concentric laminations having low porosity, and the common occur-rence of apatite among struvite-containing urinary calculi from dogs may be 2 reasons why the efficacy of dietary and medicinal manipulations in dissolving urinary calculi is greater among cats than it is among dogs. (Am J Vet Res 1996;57:1274-1287)