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N G Ducharme

Publications and source records attributed to N G Ducharme.

At least 19 recordsLinked to original sources
PubMed2003

Investigations into the role of the thyrohyoid muscles in the pathogenesis of dorsal displacement of the soft palate in horses.

REASONS FOR PERFORMING STUDY: Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate during exercise so that management of this condition could be enhanced. HYPOTHESIS: That the thyrohyoid muscles play an important role in the stability of the laryngo-palatal relationship and that dysfunction of these muscles leads to dorsal displacement of the soft palate (DDSP) during exercise. METHODS: Ten horses were exercised on a high-speed treadmill under 4 different treatment conditions: control conditions (n = 10), after resection of thyrohyoid muscles (TH, n = 10), after sham-treatment (n = 5), or after restoration of function of the thyrohyoid muscles with surgical sutures (prosthesis-treatment, n = 6). During trials, the following determinations were made: videoendoscopy of the upper airway, gait frequency and pharyngeal and tracheal static pressures. RESULTS: None of the 10 horses developed DDSP during 2 separate treadmill-exercise trials under the control conditions. Seven of the 10 horses developed DDSP after resection of the TH muscles, 4 of 5 of these horses still experienced DDSP after sham-treatment, but 5 of 6 horses no longer experienced DDSP at exercise after the prosthesis-treatment. There were significant anomalies in airway pressures, respiratory frequency, and occurrence of DDSP in both the TH resection and sham-treatment conditions compared to control conditions. In contrast, no statistical differences were noted in any of the parameters measured between the prosthesis-treatment and control conditions. CONCLUSIONS: That the function of the TH muscles is important to the stability of the laryngo-palatal relationship and plays a role in the pathophysiology of exercise-induced DDSP. POTENTIAL RELEVANCE: Management of horses with DDSP could be enhanced by restoring the function of the TH muscles.

Animals↗
PubMed2001

Subchondral cystic lesions of the proximal extremity of the tibia in horses: 12 cases (1983-2000).

OBJECTIVE: To determine clinical and radiographic features of subchondral cystic lesions (SCL) of the proximal extremity of the tibia in horses that could be used to classify these lesions as being related to osteochondrosis or osteoarthritis and to evaluate results of surgical debridement. DESIGN: Retrospective study. ANIMALS: 12 horses with 14 SCL. PROCEDURE: Medical records and radiographs obtained before and after treatment were reviewed. RESULTS: In 6 young horses (8 lesions), SCL were considered to be related to osteochondrosis; all involved the lateral tibial condyle. The remaining 6 horses were mature and had radiographic evidence of osteoarthritis in addition to SCL. Arthroscopic debridement was performed in 4 horses in which lesions were considered to be a result of osteochondrosis and in 3 horses with osteoarthritis. Three horses in which SCL were considered to be a result of osteochondrosis performed athletically after debridement. Two horses with moderate osteoarthritis returned to work after arthroscopic debridement but at a lower level of athletic performance. One horse with SCL related to osteochondrosis responded to medical treatment and went on to race. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that arthroscopic debridement of SCL is feasible in horses in which lesions involve the cranial portion of the lateral or medial tibial condyle, and that treated horses may be able to perform athletically.

Animals↗
PubMed1999

Pulmonary capillary pressure in horses undergoing alteration of pleural pressure by imposition of various upper airway resistive loads.

We hypothesized that changes in pleural pressure induced by resistive breathing would affect transmural pulmonary artery, pulmonary capillary, and pulmonary wedge pressures. Seven horses were assigned to exercise with each of 4 upper respiratory resistive loads in random order at intervals of at least 2 days: 1) control--no added resistive loads; 2) inspiratory resistive load (Iobst)--left laryngeal hemiplegia; 3) expiratory resistive load (Eobst)--one-way valve in the right nostril; and 4) combined inspiratory and expiratory resistive loads (CIEobst)--left nostril occlusion. On each occasion, the horses performed an incremental exercise protocol consisting of exercise episodes of 3 min duration at 75, 90, and 100% of maximal heart rate (HRmax). Pulmonary artery and oesophageal pressures were recorded continuously. Subsequent analysis was carried out on the pulmonary arterial pressure signal with the oesophageal pressure signal subtracted, hence the pulmonary vascular pressures in this paper approximate transmural pressures. Pulmonary vascular pressures, heart rate, and arterial blood gas tensions were measured at each level of exercise. Pulmonary capillary and pulmonary wedge pressures were determined from the pulmonary artery waveform after dynamic occlusion of a branch of the pulmonary artery. During exercise, peak expiratory oesophageal pressure was more positive in horses with Eobst and CIEobst (adjusted means = 43, and 39 mmHg, respectively) compared with control (adjusted mean = 23 mmHg) (P = 0.0001). Peak inspiratory oesophageal pressure was more negative in horses at exercise with Iobst and CIEobst (adjusted means = -42 and -39 mmHg, respectively) compared with control (adjusted mean = -26 mmHg) (P = 0.0012). Eobst was associated with an increase in mean oesophageal pressure while Iobst was associated with a decrease in mean oesophageal pressure. There were significant increases in mean pulmonary artery pressure in horses with CIEobst (adjusted means = 82 mmHg) and in pulmonary wedge pressure in horses with CIEobst and Iobst (adjusted means = 51, and 55 mmHg, respectively) when compared to control (73 and 42 mmHg, respectively) (P = 0.0001). Pulmonary capillary pressure was significantly increased in horses with CIEobst or Iobst (adjusted means = 61 mmHg, 63 mmHg, respectively) when compared to control (adjusted mean = 50 mmHg)(P = 0.0001). At maximal exercise intensity with inspiratory obstruction, the mean oesophageal (pleural) pressure was -17 mmHg while the mean pulmonary capillary pressure was 77 mmHg. The latter exceeds the reported 75 mmHg threshold for capillary failure in horses. We conclude that inspiratory resistive breathing can lead to a significant increase in transmural pulmonary capillary pressure which may contribute to loss of capillary integrity and rupture.

Airway Resistance↗
PubMed1999

Effects of frusemide on pulmonary capillary pressure in horses exercising on a treadmill.

We hypothesised that frusemide would decrease pulmonary capillary pressure in horses during strenuous exercise. Seven horses were tested after receiving saline or frusemide (2 mg/kg bwt) in random order with an interval of at least one week. Measurements were made with the horses standing, exercising at 75, 90 and 100% HRmax (maximal heart rate), and then walking 2 min after cessation of 100% HRmax. The exercise tests lasted for approximately 3 min with an interval of walking between them. Pulmonary artery and oesophageal pressures were recorded continuously and subsequent analysis of the pulmonary artery pressure signal was carried out after subtraction of the oesophageal pressure signal. Pulmonary arterial pressure, pulmonary capillary pressure, pulmonary artery wedge pressure, breathing rate, heart rate and arterial blood gas tensions were recorded at each level of exercise. Pulmonary arterial wedge and pulmonary capillary pressures were determined from the pulmonary arterial waveform after dynamic occlusion of a branch of the pulmonary artery. The resulting decay in pressure was submitted to exponential curve fitting and the amplitude on this curve at the moment of occlusion was recorded as pulmonary capillary pressure. When adjusted for horse and exercise intensity, horses receiving frusemide had lower pulmonary capillary and wedge pressures (adjusted least-squares means = 36 mmHg and 28 mmHg, respectively) when compared with control values (adjusted least-squares means = 41 mmHg (P = 0.042) and 35 mmHg (P = 0.002), respectively). Pulmonary arterial pressure, breathing rate, heart rate and arterial blood gas tensions did not differ between treatments at any exercise intensity. We conclude that frusemide reduces pulmonary capillary and wedge pressures. This is compatible with reduced transcapillary filtration and, therefore, reduced accumulation of lung water at exercise. It may also account for the putative protective effect of frusemide against exercise-induced pulmonary haemorrhage.

Acid-Base Equilibrium↗
PubMed1999

Oral nitroglycerin paste did not lower pulmonary capillary pressure during treadmill exercise.

We hypothesised that 22.5 mg of oral nitroglycerin would cause pulmonary vasodilation and therefore decrease pulmonary capillary pressure in horses during strenuous exercise. Six horses were assigned to exercise twice, once with no medication (control) and once with nitroglycerin (22.5 mg orally) in random order. Horses were exercised for 3 min each at 75, 90 and 100% of maximal heart rate (HRmax) with a 2 min period of walking between each period of exertion. Pulmonary artery and oesophageal pressures were recorded continuously. Subsequent analysis was carried out on the pulmonary arterial pressure signal with the oesophageal pressure subtracted, hence pulmonary vascular pressures reported in this paper approximate transmural pressures. Pulmonary arterial pressure, pulmonary arterial wedge pressure, pulmonary capillary pressure, heart rate and arterial blood gas tensions were determined for each level of exercise. Pulmonary arterial wedge and pulmonary capillary pressures were determined from the pulmonary artery waveform after dynamic occlusion of a branch of the pulmonary artery. The resulting decay in pulmonary artery pressure was submitted to an exponential curve fitting and the amplitude at the moment of occlusion on this curve was recorded as pulmonary capillary pressure. The effects of nitroglycerin on the various parameters were evaluated using a 3-way ANOVA blocked on horse treatment, and exercise intensity, followed by Tukey's multiple comparison procedure. Resting pulmonary artery pressure decreased from mean +/- s.e. 34.0 +/- 5.5 mmHg to 24.0 +/- 3.9 mmHg 5 min after administration of nitroglycerin (P < 0.05) but there were no significant effects on pulmonary capillary or wedge pressures. Nitroglycerin at this dose resulted in no significant differences in pulmonary artery, pulmonary capillary, and pulmonary wedge pressure, heart rate, arterial oxygen tension or arterial carbon dioxide tension at 75, 90 and 100% of HRmax. This dose of nitroglycerin does not appear significantly to protect the pulmonary vascular bed from exercise-induced hypertension. These data do not support the use of this dose of oral nitroglycerin in the prevention of EIPH.

Administration, Oral↗
PubMed1999

Effects of extrathoracic airway obstruction on intrathoracic pressure and pulmonary artery pressure in exercising horses.

OBJECTIVE: To determine whether dorsal displacement of the soft palate (DDSP) results in pulmonary artery hypertension and leads to increases in transmural pulmonary artery pressure (TPAP); to determine whether pulmonary hypertension can be prevented by prior administration of furosemide; and to determine whether tracheostomy reduces pulmonary hypertension. ANIMALS: 7 healthy horses. PROCEDURE: Horses were subjected to 3 conditions (control conditions, conditions after induction of DDSP, and conditions after tracheostomy). Horses were evaluated during exercise after being given saline (0.9% NaCl) solution or furosemide. RESULTS: Controlling for drug, horse, and speed of treadmill, DDSP-induced increase in intrathoracic pressure was associated with a significant increase in minimum (36 mm Hg), mean (82 mm Hg), and maximum (141 mm Hg) pulmonary artery pressure, compared with values for control horses (30, 75, and 132 mm Hg, respectively). Increases in pulmonary artery pressure did not induce concomitant increases in TPAP. Tracheostomy led to a significant reduction of minimum (53 mm Hg), and mean (79 mm Hg) TPAP pressure, compared with values for control horses (56 and 83 mm Hg, respectively). When adjusted for horse, speed of treadmill, and type of obstruction, all aspects of the pulmonary artery and TPAP curves were significantly decreased after administration of furosemide, compared with those for horses given saline (0.9% NaCl) solution. CONCLUSIONS: DDSP was associated with increases in pulmonary artery pressure but not with increases in TPAP. CLINICAL RELEVANCE: Expiratory obstructions such as DDSP are likely to result in pulmonary hypertension during strenuous exercise, but may not have a role in the pathogenesis of exercise-induced pulmonary hemorrhage.

Airway Obstruction↗
PubMed1998

Shoulder joint luxation in large animals: 14 cases (1976-1997).

OBJECTIVE: To determine clinical and radiographic findings in and treatment and outcome of large animals with shoulder joint luxations. DESIGN: Retrospective study. ANIMALS: 5 horses, 3 goats, 1 calf, 1 sheep, 1 Himalayan tahr, 1 pot-bellied pig, 1 reindeer, and 1 white-tailed deer. PROCEDURE: Medical records and radiographs were reviewed to determine signalment, history, physical examination findings, type of luxation, treatment, and outcome. Owners and referring veterinarians were contracted for follow-up information. RESULTS: Goats, sexually intact males, and animals < 1 year old were overrepresented, compared with the general hospital population during the study period. Closed reduction was attempted in 3 animals and was successful in 1. Open reduction and internal stabilization was attempted in 4 animals, including 1 in which closed reduction was unsuccessful. Long-term stabilization of the joint was achieved in 3 animals, but overall results were poor because of osteoarthritis and chronic lameness. Three animals were not treated, and 5 were euthanatized because of a poor prognosis. CLINICAL IMPLICATIONS: Large animals with shoulder joint luxation and concurrent fractures had a poorer prognosis than did those with shoulder joint luxation alone.

Animals↗
PubMed1998

Concurrent abomasal displacement and perforating ulceration in cattle: 21 cases (1985-1996).

OBJECTIVE: To evaluate the association of physical examination and clinicopathologic findings with surgical findings in cattle with concurrent abomasal displacement and perforating ulceration, to determine short- and long-term survival rates in these cattle, and to determine whether degree of peritonitis (focal vs diffuse) influences survival rates. DESIGN: Retrospective study. ANIMALS: 21 cattle with concurrent abomasal displacement and perforating ulceration and 42 cattle with uncomplicated abomasal displacement. PROCEDURE: Information on signalment, stage of lactation, physical examination findings, clinicopathologic data, surgical diagnosis, procedure(s) performed, and necropsy findings were retrieved from medical records of all cattle included in this study. Differences between physical examination findings of cattle with concurrent disease and those of cattle with uncomplicated displacements were evaluated, as were differences between survival rates in cattle with focal versus diffuse peritonitis. RESULTS: Cattle with concurrent disease had a greater probability of having pneumoperitoneum and signs of abdominal pain identified on physical examination than did cattle with uncomplicated diseases. There was no relationship between clinicopathologic data and survival time. Short-term survival rate was 38%, and degree of peritonitis significantly influenced survival time in cattle with concurrent abomasal displacement and perforating ulceration. Long-term survival rate in these cattle was 14%. CLINICAL IMPLICATIONS: Cattle with concurrent displaced abomasum and perforating ulceration have a poor chance for survival. In addition to detection of displaced abomasum, physical examination findings that can help lead to a presurgical diagnosis of this syndrome are pneumoperitoneum and signs of abdominal pain.

Abdominal Pain↗
PubMed1997

Pulmonary-locomotory interactions in exercising dogs and horses.

In exercising quadrupeds, limb movement is often coupled with breathing frequency. This finding has lead some investigators to conclude that locomotory forces, associated with foot plant, abdominal visceral displacements or lumbo-sacral flexion, are the primary determinants of airflow generation. Analysis of respiratory muscle electrical activation (EMG) and contraction profiles in chronically instrumented dogs and horses, along with measurements of esophageal pressure (Pes) changes and limb movements, provide evidence that each breath during the exercise hyperpnea is determined by respiratory neuromuscular events. Specifically: (1) Phasic diaphragmatic EMG and tidal shortening are always synchronous with decreases in Pes; (2) decrements in Pes are always associated with inspiratory flow generation; and (3) strict phase coupling between breathing and stride frequency is not obligatory. Thus, although locomotory-associated forces may minimally assist with flow generation, they are not the primary determinants of breathing during exercise.

Animals↗
PubMed1997

Effects of airway obstruction on transmural pulmonary artery pressure in exercising horses.

OBJECTIVE: To determine whether laryngeal hemiplegia would increase transmural pulmonary artery pressure (TPAP). ANIMALS: 6 horses. DESIGN: Horses were studied under 5 conditions: control conditions, after induction of left laryngeal hemiplegia, during obstruction of the left nostril, after placement of an instrumented tracheostomy, and after placement of an open tracheostomy. Horses were evaluated after being given saline solution and after being given furosemide. PROCEDURES: Horses were exercised on a high speed treadmill, using a maximum speed of 13 m/s. During each exercise, airway pressures, airflow, esophageal and pulmonary artery pressures, and blood gas partial pressures were measured. RESULTS: When adjusted for horse, speed, and obstruction condition, mean TPAP (pulmonary artery pressure-esophageal pressure) and minimum TPAP were significantly lower after administration of furosemide than after administration of saline solution. In horses given saline solution, respiratory obstruction that increased intrapleural pressure significantly increased mean TPAP, and respiratory obstruction that decreased intrapleural pressure significantly decreased minimum TPAP. CONCLUSIONS: Changes in intrapleural pressure appear to play an important role in pulmonary artery pressure and TPAP. CLINICAL RELEVANCE: Because induction of laryngeal hemiplegia did not increase TPAP, laryngeal hemiplegia is unlikely to contribute to development of exercise-induced pulmonary hemorrhage.

Airway Obstruction↗
PubMed1996

The effect of exercise on diaphragmatic activation in horses.

Horses chronically-instrumented with costal diaphragmatic electromyographic electrodes were studied during exercise while unencumbered by a breathing mask. Exercise-associated changes in esophageal (Pes), gastric (Pga) and transdiaphragmatic (Pdi) pressures were measured and related to diaphragmatic electromyographic activity (CS EMG) and to left forelimb impact. In all breaths examined, CS EMG always coincided with decrements in Pes. For all exercise trials, linear increases in CS EMG, Pga and Pdi and linear decreases in Pes, as a function of exercise intensity, always occurred. During all gaits, breathing frequency (fR) was entrained with stride frequency (fS) one for one. However, a constant phase-coupling relationship between fR and fS, observed when horses cantered and galloped, was absent when horses walked or trotted. We conclude that biomechanical forces contribute minimally to ventilation in exercising horses, that the diaphragm is always phasically active during each breath and its total electrical activity and mechanical output are proportional to the exercise hyperpnea.

Animals↗
PubMed1996

Stifle injuries in cattle.

Lameness of the hindlimbs originating from the stifle joint may be difficult to diagnose and treat. This article describes anatomic considerations and the diagnostic procedures necessary to accurately evaluate the bovine stifle joint. The emphasis is toward obtaining a diagnosis based on physical examination and simple diagnostic procedures in field situation. Specific treatments and/or management alternatives for cattle with various ligament injuries (cranial cruciate rupture, collateral ligament injuries), or with luxated patella, upward fixation of the patella, septic arthritis, and subchondral bone cysts are described. Current knowledge of the prognosis after various treatments is presented.

Animals↗
PubMed1995

Scintigraphy for diagnosis of avulsions of the origin of the suspensory ligament in horses: 51 cases (1980-1993).

The medical records of 34 horses with a diagnosis of avulsion of the origin of the suspensory ligament that had been admitted to the veterinary medical teaching hospital between 1980 and 1993 were identified. In addition to clinical examination, 21 of 34 horses had scintigraphy and radiography performed during their examination. The usefulness of scintigraphy and radiography were assessed by comparing the initial findings reported in the medical record to those obtained in a retrospective review of the images. Thirty other horses with scintigraphic lesions of the proximal aspect of the third metacarpal/metatarsal bone but with a confirmed diagnosis other than avulsion of the suspensory ligament served as controls for lesion specificity. Scintigraphy (bone phase, n = 21) revealed increased uptake in all horses in both reviews. Only 14 of 21 (67%) horses radiographed, however, had at least 1 lesion during the initial radiographic evaluation that was reported to be suggestive of avulsion. When the radiographs were reviewed retrospectively, the radiologist identified 18 of 21 (86%) horses with lesions consistent with avulsion. The interpretation of scintigraphy appeared to be a more repeatable and sensitive diagnostic method than radiography. However, though scintigraphy was sensitive in identifying inflammation of the proximal aspect of the metacarpal/metatarsal region, no specific diagnosis of avulsion could be made without coincident radiography; the specificity of scintigraphy in diagnosing avulsion of the suspensory ligament was only 41% (21/51).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Measurement of upper airway pressures in exercising horses with dorsal displacement of the soft palate.

To determine whether abnormal airway pressures have a role in development of dorsal displacement of the soft palate (DDSP), measurements of tracheal and pharyngeal pressures were correlated with nasopharyngeal morphology in exercising horses. Exercising videoendoscopy and measurement of tracheal and pharyngeal pressures were used in 14 clinically normal horses and 19 horses with intermittent DDSP. The pressure signals were superimposed on the videoendoscope image, and both images were saved simultaneously on a videocassette for slow motion analysis to determine the instant displacement occurred in the respiratory cycle. Horses were submitted to an escalating 8-minute high-speed test with a maximal speed of 14 m/s. Compared with clinically normal horses, horses with intermittent DDSP did not have excessively negative inspiratory pressures during exercise. Eight horses displaced the soft palate during inspiration, 4 horses displaced it during expiration, and 7 displaced it by swallowing. Some horses displaced the soft palate at the beginning of the exercise trial, before reaching maximal speed, some horses displaced it at the peak speed, and some horses displaced it when slowing down. Epiglottic size in horses with DDSP was within normal limits, ruling out epiglottic hypoplasia as a cause of DDSP during exercise. Airway pressures were significantly (P < 0.002) altered after DDSP. Pharyngeal and tracheal inspiratory pressures were less negative, whereas pharyngeal expiratory pressure became less positive and tracheal expiratory pressure became more positive after displacement, suggesting a decrease in airflow and an increase in expiratory resistance in the upper airway.

Airway Obstruction↗
PubMed1995

Regulation of respiratory muscle activities during chemoreceptor stimulation in adult horses.

We examined the electromyographic activity of the costal portion of the diaphragm and the transverse abdominal and external oblique muscles in 6 chronically instrumented awake adult horses during eupneic breathing, during 2 levels of hypercapnia (fractional concentration of inspired CO2; FICO2 = 0.4 and 0.6), and during 2 levels of hypocapnic hypoxia (FIO2 = 0.15 and 0.12). Using the inert gas technique, we also measured the end-expiratory lung volumes of the 6 horses during eupnea, 6% CO2 challenge, and 12% O2 breathing. During eupneic breathing, phasic electrical activity of these 3 muscles was always present and was preceded by the onset of mechanical flow. At progressive levels of hypercapnia, the magnitude of inspiratory and expiratory electrical activity increased, and for the expiratory muscles, this recruitment coincided with significant (P < 0.05) increases in peak expiratory gastric pressure. However, during hypocapnic hypoxia, differential recruitment patterns of the respiratory muscles were found. The electrical activity of the diaphragm increased in magnitude and occurred sooner relative to the onset of mechanical flow. The magnitude and onset of abdominal expiratory activity failed to increase significantly during these episodes of hyperpnea and this pattern of activity coincided with decrements in peak expiratory gastric pressure. Despite alterations in muscle recruitment patterns during these hyperpneic episodes, end-expiratory lung volume remained unchanged. Thus, we conclude that adult horses respond similarly to awake dogs during peripheral and central chemoreceptor stimulation.

Animals↗
PubMed1994

Measurements of blood flow and xanthine oxidase activity during postischemic reperfusion of the large colon of ponies.

To assess right colic artery blood flow and relevance of xanthine dehydrogenase/xanthine oxidase after experimentally induced strangulation obstruction and reperfusion of the colon, 5 ponies were subjected to 2.5 hours of complete ischemia of the left dorsal and ventral colons, allowed to recover from surgery, and monitored during a 48-hour reperfusion period. Five ponies were subjected to sham surgery and served as controls. All ponies had a Doppler ultrasound blood flow monitor implanted on the right colic artery near the pelvic flexure 10 to 14 days prior to the ischemic period. Colic artery blood flow was monitored prior to, during, and for 4 hours after surgery. Blood samples from the right colic artery and vein distal to the obstruction site were collected during surgery (prior to ischemia, after 1 and 2 hours of ischemia, and after 10 and 60 minutes of reperfusion) for determination of arterial and venous blood gas tensions and electrolytes. Prior to surgery, blood selenium and plasma vitamin E (alpha-tocopherol) concentrations and blood glutathione peroxidase (GPX) activity were determined to assess the status of endogenous antioxidants. Combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone (nanomoles per minute per gram of tissue) were determined, using a dual-spectrophotometric technique. Xanthine dehydrogenase and oxidase activities were determined prior to ischemia, after 1 and 2 hours of ischemia, and at 1 and 48 hours after reperfusion. Median blood flow in the experimental and control groups (156 ml/min and 110 ml/min, respectively) was not statistically different before surgery, and was significantly (P < 0.02) lower in the experimental (4 ml/min) vs the control group (72.5 ml/min) during the ischemic period. Experimental ponies had significantly (P < 0.03) lower right colic artery blood flow during the 4 hours immediately after recovery from anesthesia. Significant difference was not observed in right colonic venous bicarbonate concentration between groups at any time. Median right colonic venous PCO2, pH, and standard base excess were different (P < 0.001) between groups during the ischemic period only. Median venous oxygen saturation and median venous PO2 were significantly (P < 0.001) lower in the experimental ponies at the end of 2 hours of ischemia, but were significantly (P < 0.05) increased during the reperfusion phase. Median venous potassium concentration was significantly (P < 0.01) higher in experimental ponies during the ischemic and reperfusion phases. Vitamin E and GPX values were within normal limits for all ponies.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗