Effect of Hypotension and Dobutamine on Gastrointestinal Microcirculations of Healthy, Anesthetized Horses.

Horses undergoing abdominal exploratory surgery are at risk of hypotension and hypoperfusion. Normal mean arterial pressure is used as a surrogate for adequate tissue perfusion. However, measures of systemic circulation may not be reflective of microcirculation. This study measured the mean arterial pressure, cardiac index, lactate, and four microcirculatory indices in six healthy, anesthetized adult horses undergoing elective laparotomies. The microcirculatory parameters were measured at three different sites along the gastrointestinal tract (oral mucosa, colonic serosa, and rectal mucosa) with dark-field microscopy. All macro- and microcirculatory parameters were obtained when the horses were normotensive, hypotensive, and when normotension returned following treatment with dobutamine. Hypotension was induced with increases in inhaled isoflurane. The horses successfully induced into hypotension did not demonstrate consistent, expected changes in systemic perfusion or microvascular perfusion parameters at any of the three measured gastrointestinal sites. Normotension was successfully restored with the use of dobutamine, while the systemic perfusion and microvascular perfusion parameters remained relatively unchanged. These findings suggest that the use of mean arterial pressure to make clinical decisions regarding perfusion may or may not be accurate.

Using quarterly earnings to assess racing performance in 66 thoroughbreds after transendoscopic laser surgery for treatment of epiglottic entrapment.

OBJECTIVE: To assess the outcome of transendoscopic laser surgery for the treatment of epiglottic entrapment (EE) and determine the influence of preoperative morphological characteristics on outcomes. STUDY DESIGN: Retrospective cohort study. ANIMALS: Thoroughbred racehorses treated with transendoscopic laser surgery (n = 66) and untreated cohorts (n = 132). METHODS: Medical, surgical, and race records of 66 horses treated with transendoscopic laser surgery were compared with untreated cohorts randomly selected from their last race presurgery. Postsurgery data were collated as number of starts and race winnings for each quarter after the date of surgery. RESULTS: Treated horses performed worse (P = .002) than their untreated cohorts in their last race presurgery. Although treated horses raced fewer times (P < .001) and earned less money (P < .001) in the first quarter after surgery compared with untreated horses, quarterly earnings or starts did not differ between groups after the first quarter. Among variables tested, subepiglottic membrane resection was the only prognostic factor; horses requiring this resection raced fewer times (P = .001) but without a significant difference in earnings. CONCLUSION: Horses treated for EE via transendoscopic laser surgery returned to a performance standard comparable to their untreated cohorts by the second quarter postsurgery. Horses with entrapments requiring resection raced fewer times postoperatively than the untreated cohorts. CLINICAL SIGNIFICANCE: Treated horses can be expected to perform equivocally to that of untreated cohorts in all but the first quarter following surgery except in those cases where resection of the entrapping membranes is required.

Comparison of the oral and rectal mucosal and colonic serosal microcirculations of healthy, anesthetized horses.

The objectives of the study were to: i) determine baseline microvascular perfusion indices (MPI) and assess their repeatability in healthy horses under general anesthesia, and ii) compare the MPIs of 3 microvascular beds (oral mucosa, colonic serosa, and rectal mucosa). Healthy adult horses were anesthetized and sidestream dark field microscopy was used to collect video loops of the oral mucosa, rectal mucosa, and colonic serosa under normotensive conditions without cardiovascular support drugs; videos were later analyzed to produce MPIs. Baseline MPI values were determined for each site, which included the total vessel density (TVD), perfused vessel density (PVD), portion perfused vessels (PPV), and microcirculatory flow index (MFI). Differences in MPIs between microvascular beds were not statistically significant. Repeatability of the measurements varied for each MPI. In particular, the site of sampling had a profound effect on the repeatability of the PPV measurements and should be considered in future studies.

Les objectifs de cet étude étaient: i) de déterminer les indices de perfusion microvasculaires (IPM) de base et évaluer leur répétabilité chez les chevaux en bonne santé sous anesthésie générale, et ii) de comparer les IPMs de trois lits microvasculaires (muqueuse orale, séreuse du colon, et muqueuse rectale). Des chevaux adultes en bonne santé ont été anesthésiés et une unité de microscopie au champ sombre a été utilisée pour recueillir des boucles vidéo de la muqueuse buccale, de la muqueuse rectale, et de la séreuse du colon sous des conditions de tension artérielle normale. Les vidéos ont été analysées pour produire les IPMs, incluant la densité totale des vaisseaux, la densité des vaisseaux perfusés, la portion des vaisseaux perfusés, et l'index de flux microcirculaire. Pour chaque IPM, les différences entre les sites anatomiques n'étaient pas significatives statistiquement. La répétabilité des mesures variait pour chaque IPM. En particulier, le type de lit microvasculaire a une influence profonde sur la répétabilité des mesures.(Traduit par les auteurs).

A profile of morbidity and mortality rounds within resident training programs of the American College of Veterinary Surgeons.

OBJECTIVE: To describe the structure and role of morbidity and mortality rounds (MMR) in resident training programs of the American College of Veterinary Surgeons (ACVS). STUDY DESIGN: Cross-sectional analysis: survey. SAMPLE POPULATION: ACVS surgical resident program directors. METHODS: Electronic surveys consisting of 27 questions were sent to the directors of 142 ACVS resident programs. RESULTS: Forty-five (31.6%) programs completed the survey, including 24 (53.3%) from small animal programs and 21 (46.7%) from large animal programs. Thirty-two (71.1%) programs incorporated regular MMR in their training. The primary goal of these rounds was improvement of patient care (63%) and education (31%). Selection of cases was based on unexpected mortality (80%), unexpected morbidity (77.4%), teaching value (65.7%), and review of medical errors (63%). Twenty-six percent of programs reported conducting formal follow-up for topics discussed during MMR. Ninety-five percent of programs believed that MMR were valuable. CONCLUSION: MMR are commonly incorporated in surgical resident training programs. The primary objectives of these rounds are to educate residents, refine hospital medical and operational policies, and to improve patient care. The majority of residency programs view MMR as worthwhile. However, the majority of veterinary residency programs fail to follow up MMR with formal initiatives for improvement and objective outcome assessments for issues identified during MMR.

Impact of walking surface on the range of motion of equine distal limb joints for rehabilitation purposes.

The aim of this study was to evaluate the effect of three footing surfaces on the flexion/extension, and range of motion (ROM) of the carpus, tarsus and fetlocks in the horse. The percentage of stride spent in the stance phase of sound horses at the walk was also measured. Nine sound horses were walked on hard ground (HD), soft ground (SF) and a land treadmill (LT), and five complete gait cycles were recorded by a digital video camera. Retro-reflective markers were placed on the skin at four anatomical locations on the left fore and hind limbs, and data were analyzed using two-dimensional (2D) motion-analysis software. Maximal flexion/extension angles and range of motion were calculated for each joint, and the percentage of the stride spent in stance phase was determined for each stride. Maximal flexion of the tarsus and hind fetlock was greater on LT and SF compared to HD, while maximal flexion of the carpus was greater on LT compared to HD and SF. Maximal extension of the carpus was greater on HD compared to SF and LT, maximal extension of the tarsus was greater on HD and SF compared to LT, and maximal extension of the forelimb and hind limb fetlocks was greater on LT compared to HD and SF. The greatest overall ROM of the carpus and fetlocks was achieved on LT, while the greatest overall ROM of the tarsus was achieved on SF. The stance percentage of the stride for the hind limb was significantly different between all surfaces. In conclusion, walking surface influences flexion/extension of the carpus, tarsus and fetlocks in healthy horses, which should be considered when walking equine rehabilitation cases.

Effect of water depth on amount of flexion and extension of joints of the distal aspects of the limbs in healthy horses walking on an underwater treadmill.

OBJECTIVE: To determine the maximum amount of flexion and extension of the carpal, tarsal, metacarpophalangeal, and metatarsophalangeal joints and the percentage duration of the stance and swing phases of the stride for horses walking on an underwater treadmill in various water depths. ANIMALS: 9 healthy adult horses. PROCEDURES: Zinc oxide markers were placed on the forelimbs and hind limbs of the horses. Video was recorded of horses walking (0.9 m/s) on an underwater treadmill during baseline conditions (< 1 cm of water) or in various amounts of water (level of the metatarsophalangeal, tarsal, and stifle joints). Maximum amount of joint flexion and extension, range of motion (ROM), and the percentage durations of the stance and swing phases of the stride were determined with 2-D motion analysis software. RESULTS: The ROM was greater for all evaluated joints in any amount of water versus ROM for joints in baseline conditions (primarily because of increases in amount of joint flexion). The greatest ROM for carpal joints was detected in a tarsal joint water depth, for tarsal joints in a stifle joint water depth, and for metacarpophalangeal and metatarsophalangeal joints in metatarsophalangeal and tarsal joint water depths. As water depth increased, the percentage durations of the stance and swing phases of the stride significantly decreased and increased, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study suggested that exercise on an underwater treadmill is useful for increasing the ROM of various joints of horses during rehabilitation and that the depth of water affects the amount of flexion and extension of joints.