Use of micro-lightguide spectrophotometry for evaluation of microcirculation in the small and large intestines of horses without gastrointestinal disease.

OBJECTIVE: To evaluate the use of a micro-lightguide tissue spectrophotometer for measurement of tissue oxygenation and blood flow in the small and large intestines of horses under anesthesia. ANIMALS: 13 adult horses without gastrointestinal disease. PROCEDURES: Horses were anesthetized and placed in dorsal recumbency. Ventral midline laparotomy was performed. Intestinal segments were exteriorized to obtain measurements. Spectrophotometric measurements of tissue oxygenation and regional blood flow of the jejunum and pelvic flexure were obtained under various conditions that were considered to have a potential effect on measurement accuracy. In addition, arterial oxygen saturation at the measuring sites was determined by use of pulse oximetry. RESULTS: 12,791 single measurements of oxygen saturation, relative amount of hemoglobin, and blood flow were obtained. Errors occurred in 381 of 12,791 (2.98%) measurements. Most measurement errors occurred when surgical lights were directed at the measuring site; covering the probe with the surgeon's hand did not eliminate this error source. No measurement errors were observed when the probe was positioned on the intestinal wall with room light, at the mesenteric side, or between the mesenteric and antimesenteric side. Values for blood flow had higher variability, and this was most likely caused by motion artifacts of the intestines. CONCLUSIONS AND CLINICAL RELEVANCE: The micro-lightguide spectrophotometry system was easy to use on the small and large intestines of horses and provided rapid evaluation of the microcirculation. Results indicated that measurements should be performed with room light only and intestinal motion should be minimized.

In vitro effects of lidocaine on contractility of circular and longitudinal equine intestinal smooth muscle.

The purpose of the study was to compare the contractility-enhancing effects of lidocaine in equine jejunal circular (CSM) and longitudinal smooth muscle (LSM) in vitro. In previous studies, more pronounced effects of lidocaine were observed in ischaemia-reperfusion (IR) injured smooth muscle. Therefore in this study, effects were examined in both non-injured control tissues and tissues challenged by a defined, artificial IR injury. Isometric contractile performance of CSM and LSM, assessed by frequency (F), amplitude (A) and mean active force (MAF) of contractions, was defined as contractility. LSM featured lower basic contractility compared to CSM. Lidocaine provoked contractility-enhancing effects in both smooth muscle layers, but except for F at high lidocaine concentrations, contractility of LSM remained lower throughout the trial. Additionally, higher lidocaine concentrations were required to cause significant effects in LSM. No differences were observed in contractility of control and IR injured smooth muscle, but higher lidocaine concentrations were needed to provoke effects in IR injured smooth muscle. In contrast to CSM, contractility of LSM did not decrease at comparably high lidocaine concentrations. Differences in basic contractility of CSM and LSM might be explained by physiologically lower activity of LSM per se or by a thinner LSM layer with fewer smooth muscle cells taking part in contractions. The smaller thickness of the LSM layer may also contribute to persisting discrepancies in contractility following lidocaine application. Additionally, variations in lidocaine concentrations necessary for inducing significant effects could result from differences in the molecular structure of CSM and LSM cells.

Splenectomy for treatment of suppurative splenitis caused by a reticular foreign body in a heifer.

OBJECTIVE: To report the clinical findings and treatment of a heifer with suppurative splenitis. STUDY DESIGN: Clinical report. ANIMALS: A 30-month-old heifer. METHODS: Splenectomy in the standing calf after local anesthesia and 13th rib resection. RESULTS: The heifer had an uneventful recovery but was culled because of septic tarsitis 3 months later. CONCLUSIONS: Splenectomy is a useful treatment for cattle with traumatic splenitis if diagnosed early. Partial splenectomy may have prevented the late complication of septic tarsitis. CLINICAL RELEVANCE: Suppurative splenitis is usually a complication of hardware disease and has a grave prognosis unless splenectomy is carried out.