Objective—To compare cardiovascular effects of sevoflurane alone and sevoflurane plus an IV infusion of lidocaine in horses. Animals—8 adult horses. Procedures—Each horse was anesthetized twice via IV administration of xylazine, diazepam, and ketamine. During 1 anesthetic episode, anesthesia was maintained by administration of sevoflurane in oxygen at 1.0 and 1.5 times the minimum alveolar concentration (MAC). During the other episode, anesthesia was maintained at the same MAC multiples via a reduced concentration of sevoflurane plus an IV infusion of lidocaine. Heart rate, arterial blood pressures, blood gas analyses, and cardiac output were measured during mechanical (controlled) ventilation at both 1.0 and 1.5 MAC for each anesthetic protocol and during spontaneous ventilation at 1 of the 2 MAC multiples. Results—Cardiorespiratory variables did not differ significantly between anesthetic protocols. Blood pressures were highest at 1.0 MAC during spontaneous ventilation and lowest at 1.5 MAC during controlled ventilation for either anesthetic protocol. Cardiac output was significantly higher during 1.0 MAC than during 1.5 MAC for sevoflurane plus lidocaine but was not affected by anesthetic protocol or mode of ventilation. Clinically important hypotension was detected at 1.5 MAC for both anesthetic protocols. Conclusions and Clinical Relevance—Lidocaine infusion did not alter cardiorespiratory variables during anesthesia in horses, provided anesthetic depth was maintained constant. The IV administration of lidocaine to anesthetized nonstimulated horses should be used for reasons other than to improve cardiovascular performance. Severe hypotension can be expected in nonstimulated horses at 1.5 MAC sevoflurane, regardless of whether lidocaine is administered.

Objective—To examine behavioral and physiologic effects of lipopolysaccharide (LPS)-induced mastitis in lactating dairy cows. Animals—20 Holstein cows. Procedures—Cows were assigned to 5 blocks (4 cows/block) on the basis of parity and number of days in lactation. Intramammary infusion and IV treatments were assigned in a 2 × 2 factorial arrangement. Cows within each block were assigned to receive intramammary infusion with 25 μg of LPS or sterile PBS solution 3 hours after milking, and treatment with flunixin meglumine or sterile PBS solution was administered IV 4 hours after intramammary infusion. Video monitoring was continuously performed during the study. Results—LPS-infused cows spent less time during the first 12 hours after infusion lying, eating, and chewing cud, compared with results for PBS solution-infused cows. Behavioral responses were correlated with physiologic responses for the first 12 hours after intramammary infusion. Flunixin meglumine administration after intramammary infusion mitigated some behavioral and clinical systemic responses. Conclusions and Clinical Relevance—Intramammary infusion of LPS caused changes in both behavioral and physiologic variables in lactating dairy cows. Time spent lying, eating, and chewing cud were negatively correlated with physiologic responses in cows. Evaluation of behavior patterns may provide an ancillary measure, along with evaluation of physiologic variables, for monitoring well-being, clinical responses, and recovery from acute clinical mastitis.

Objective--To characterize the temporal and spatial distribution and reproductive ratio of vesicular stomatitis (VS) outbreaks reported in Mexico in 2008. Procedures--The Poisson model of the space-time scan statistic was used to identify periods and geographical locations at highest risk for VS in Mexico in 2008. The herd reproductive ratio (Rh) of the epidemic was computed by use of the doubling-time method. Results--1 significant space-time cluster of VS was detected in the state of Michoacan from September 4 through December 10, 2008. The temporal extent of the VS outbreaks and the value and pattern of decrease of the Rh were different in the endemic zone of Tabasco and Chiapas, compared with findings in the region included in the space-time cluster. Conclusions and Clinical Relevance--The large number of VS outbreaks reported in Mexico in 2008 was associated with the spread of the disease from the endemic zone in southern Mexico to areas sporadically affected by the disease. Results suggested that implementation of a surveillance system in the endemic zone of Mexico aimed at early detection of changes in the value of Rh and space-time clustering of the disease could help predict occurrence of future VS outbreaks originating from this endemic zone. This information will help prevent VS spread into regions of Mexico and neighboring countries that are only sporadically affected by the disease.

Objective—To determine selected cardiopulmonary values and baroreceptor response in conscious green iguanas (Iguana iguana) and to evaluate the use of blood gas analysis and pulse oximetry in this species. Animals—15 healthy juvenile green iguanas. Procedures—Baseline cardiopulmonary values were determined in 15 conscious iguanas breathing room air. Effects of 100% O2 inspiration were also measured (n = 6), and the baroreceptor reflex was characterized by exponential sigmoidal curve fitting analysis. Results—Conscious iguanas had a mean ± SD resting heart rate of 52 ± 8 beats/min, respiratory rate of 28 ± 6 breaths/min, and systolic, mean, and diastolic arterial blood pressures of 69 ± 10 mm Hg, 62 ± 12 mm Hg, and 56 ± 13 mm Hg, respectively. Mean arterial pH at 37°C was 7.29 ± 0.11, Pao2 was 81 ± 10 mm Hg, and Paco2 was 42 ± 9 mm Hg; corrected for a body temperature of 30°C, mean arterial pH at 37°C was 7.382 ±0.12, Pao2 was 54 ± 15 mm Hg, and Paco2 was 32 ± 7 mm Hg. Inspiration of 100% O2 did not change heart and respiratory rates but increased Pao2 to 486 ± 105 mm Hg (corrected value, 437 ± 96 mm Hg). A baroreceptor reflex was evident, with mean heart rates ranging from 30 ± 3 beats/min to 63 ± 5 beats/min and mean arterial blood pressures ranging from 42 ± 3 mm Hg to 58 ± 3 mm Hg. Conclusions and Clinical Relevance—This study provided needed information on cardiopulmonary values in healthy green iguanas, the application and limitation of arterial and venous blood gas analysis, and the accuracy of pulse oximetry.

Objective—To determine magnetic resonance imaging (MRI) vertebral ratio values representing vertebral canal height, vertebral canal shape, and vertebral body shape in Doberman Pinschers with and without disk-associated cervical spondylomyelopathy (DACSM) and clinically normal English Foxhounds. Animals—Doberman Pinschers with (n = 18) and without (20) DACSM and clinically normal English Foxhounds (18). Procedures—All dogs underwent low-field MRI of the cervical vertebral column. From 5 specific measurements made at C3 through C7, 4 linear vertebral ratios were calculated and assessed for correlation: vertebral canal height-to-body height ratio (CBHR), vertebral canal height-to-body length ratio (CBLR), caudal canal height-to-cranial canal height ratio (CCHR), and vertebral body length-to-height ratio (BLHR). The CBHR and CBLR described vertebral canal height, CCHR described vertebral canal shape, and BLHR described vertebral body shape. A midvertebral canal-occupying ratio (mVCOR) for the spinal cord was calculated at C5. Results—Compared with both groups of unaffected dogs, CBHR, CBLR, and BLHR for Doberman Pinschers with DACSM were significantly smaller. The C7 CCHR was significantly larger in DACSM-affected Doberman Pinschers, compared with clinically normal English Foxhounds. Ratios did not differ significantly between unaffected Doberman Pinschers and clinically normal English Foxhounds. Correlation coefficients between CBHR, CBLR, and mVCOR were low and not significant. Conclusions and Clinical Relevance—Doberman Pinschers with DACSM had significantly smaller vertebral canal heights and more square-shaped vertebral bodies, compared with unaffected Doberman Pinschers, combined with a funnel-shaped vertebral canal at C7. Breed-specific differences were not evident. Linear MRI vertebral canal-to-body ratios do not appear to predict relative vertebral canal stenosis.

Objective: To determine the effect of Hct on blood glucose readings of dogs obtained by use of 2 point-of-care (POC) blood glucometers and a laboratory analyzer. Animals: 184 dogs, including 139 Greyhounds. Procedures: Venous blood samples collected from 184 dogs with a range of Hcts (measured in EDTA-anticoagulated blood) were immediately analyzed with a handheld glucometer specifically developed for veterinary use and a glucometer developed for use in humans. The remainder of each blood sample was placed in fluoride oxalate tubes, and plasma glucose concentration was measured with a laboratory analyzer. Agreement between results for the POC glucometers and laboratory analyzer and effect of Hct on glucometer accuracy was assessed via regression analysis. Results: Significant differences were detected between results of the glucometers and the reference laboratory analyzer. The Hct affected the correlation between results for the glucometers and the laboratory analyzer. Deviations of the glucometers from the reference interval varied with Hct. The glucometer for veterinary use more closely correlated with the glucose concentration when Hct was within or above its reference interval. The glucometer for use in humans more closely approximated laboratory reference glucose concentrations in anemic dogs. Conclusions and Clinical Relevance: Hct had a relevant impact on the correlation between whole blood and plasma glucose concentrations in dogs. Significant variations between results obtained with the 2 glucometers could be critical when interpreting blood glucose measurements or selecting a POC glucometer for an intensive care setting and precise glycemic control in critically ill dogs.

Objective: To compare echocardiographic variables of dogs with postmortem anatomic measurements and histologic characteristics of the mitral valve (MV). Animals: 21 cardiologically normal dogs. Procedures: The MV was measured echocardiographically by use of the right parasternal 5-chamber long-axis view. Dogs were euthanized, and anatomic measurements of the MV annulus (MVa) were performed at the level of the left circumflex coronary artery. Mitral valve leaflets (MVLs) and chordae tendineae were measured. Structure of the MVLs was histologically evaluated in 3 segments (proximal, middle, and distal). Results: Echocardiographic measurements of MVL length did not differ significantly from anatomic measurements. A positive correlation was detected between body weight and MVa area. There was a negative correlation between MVa area and the percentage by which the MVL area exceeded the MVa area. Anterior MVLs had a significantly higher number of chordae tendineae than did posterior MVLs. Histologically, layering of MVLs was less preserved in the distal segment, whereas the muscular component and adipose tissue were significantly more diffuse in the proximal and middle segments. Conclusions and Clinical Relevance: The MV in cardiologically normal dogs had wide anatomic variability. Anatomic measurements of MVL length were correlated with echocardiographic measurements.

Objective—To induce ischemia and reperfusion injury in the large colon mucosa of horses in vivo and evaluate the recovery and effects of components of an organ transplant solution on mucosal recovery in vitro. Animals—6 healthy horses. Procedures—Horses were anesthetized, and ischemia was induced for 60 minutes in the pelvic flexure, which was followed by reperfusion for 240 minutes. Ischemic (n = 4 horses), reperfused (6), and adjacent control (6) colonic mucosae were isolated for in vitro testing and histologic examinations. Tissues were mounted in Ussing chambers with plain Krebs Ringer bicarbonate (KRB), KRB with N-acetylcysteine (NAC), or KRB with a modified organ transplant solution (MOTS). Transepithelial electrical resistance (TER) and mannitol flux were used to assess mucosal integrity. Data were analyzed by use of ANOVA and Kruskal-Wallis tests. Results—The TER in reperfused tissues was similar to the TER in control tissues and greater than the TER in ischemic tissues, which was consistent with morphological evidence of recovery in reperfused tissues. Mannitol flux was greater in ischemic tissues than in reperfused tissues. The TER and mannitol flux were not significantly affected by incubation of mucosa with NAC or MOTS. Conclusions and Clinical Relevance—Ischemia induced during the brief period allowed rapid mucosal repair and complete recovery of tissue barrier properties during reperfusion. Therefore, reperfusion injury was not observed for this method of ischemic damage in equine colonic mucosa.

Objective—To evaluate effects of imaging plane, flexion and extension, patient weight, and observer on computed tomographic (CT) image measurements of the area of the lumbosacral (L7-S1) intervertebral foramen (LSIF) in dogs. Sample—12 dog cadavers (2 were excluded because of foraminal stenosis). Procedures—In each cadaver, sagittal, sagittal oblique, transverse oblique, and double oblique CT images were obtained at 3 zones (entrance, middle, and exit zones) of the region of the lateral lumbar spinal canal that comprises the LSIF while the lumbosacral junction (LSJ) was positioned in flexion or extension. Barium-impregnated polymethylmethacrylate was used to fill the intervertebral foramina to aid boundary detection. Measurements of interest were obtained. Results—Among the dog cadavers, there was large variability in LSIF cross-sectional areas (range, 0.12 to 0.44 cm2; SD, 0.1 cm2) and in foraminal angles required to obtain a double oblique plane in LSJ extension (SD, 8° to 9°). For LSIF area measurements in standard sagittal CT images, interobserver variability was 23% to 44% and intraobserver variability was 4% to 5%. Sagittal oblique images obtained during LSJ extension yielded smaller mean LSIF areas (0.30 cm2), compared with findings in sagittal images (0.37 to 0.52 cm2). The exit and middle zone areas were smaller than the entrance zone area in sagittal images obtained during LSJ extension. Conclusions and Clinical Relevance—Repeated measurements of the LSIF area in images obtained during LSJ extension may be unreliable as a result of interobserver variability and the effects of dog positioning and CT slice orientation.

Objective--To develop a standardized meal challenge test by assessing associations between food-withheld preprandial (ie, fasting) and postprandial triglyceride concentrations, determining the most appropriate sampling time to detect the peak concentration (highest postprandial concentration), and estimating reference intervals for fasting and postprandial concentrations in healthy dogs. Animals--12 lean healthy mixed-breed dogs. Procedures--Dogs were fed a dry commercially available diet (fat, 31% metabolizable energy) for 3 weeks. After food was withheld for 23 to 24 hours, plasma triglyceride concentrations were measured 1 and 0.083 hours before and 1, 2, 3, 4, 5, 6, 9, and 12 hours after feeding of a standardized challenge meal (median amount eaten, 63 kcal/kg [127 kcal/kg0.75]). Correlation and agreement between concentrations at peak and other time points were assessed by use of correlation coefficients and Bland-Altman limits of agreement. Reference intervals were calculated by use of a robust method. Results--Fasting and peak triglyceride concentrations were not closely associated. The highest concentration among samples obtained 2, 5, and 6 hours after meal consumption had closest agreement with peak concentration. In 5 of 12 dogs, concentrations 12 hours after eating were still significantly above baseline concentration (mean of each dog's fasting concentrations). Conclusions and Clinical Relevance--Fasting triglyceride concentration could not be used to accurately predict peak concentration. When estimating peak concentration, multiple samples should be collected 2, 5, and 6 hours after consumption of a standardized meal. Food may need to be withheld for > 12 hours when assessing fasting concentrations in healthy dogs.