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Biomedical subjects

J A Stick

Publications and source records attributed to J A Stick.

At least 73 records · Page 4Linked to original sources
PubMed1988

Effects of flunixin meglumine on jejunal blood flow, motility, and oxygen consumption in ponies.

Using isolated autoperfused intestinal segments, the effects of flunixin meglumine administration on systemic arterial blood pressure, jejunal blood flow, vascular resistance, motility, arteriovenous oxygen difference, and oxygen consumption were determined in 10 anesthetized ponies ventilated with a mixture of halothane and oxygen. Saline solution or flunixin meglumine (1.1 mg/kg of body weight) was infused as a single bolus into the left jugular vein. By 10 minutes, flunixin meglumine increased systemic arterial blood pressure and increased intestinal vascular resistance. The jejunal blood flow, however, was not significantly decreased until 1 hour after flunixin meglumine administration. Intestinal motility, arteriovenous oxygen difference, and oxygen consumption were unchanged. Results indicated that acute administration of flunixin meglumine increases systemic arterial pressure and intestinal vascular resistance, but the resulting intestinal vasoconstriction does not lead to compromise of intestinal viability.

Animals↗
PubMed1987

Effects of xylazine on equine intestinal vascular resistance, motility, compliance, and oxygen consumption.

Isolated jejunal segments were perfused at a constant blood flow rate to determine simultaneously the effects of xylazine on intestinal vascular resistance, motility, compliance, and oxygen consumption in 12 anesthetized ponies. Xylazine was infused into the artery perfusing the intestinal segment (group 1), or into the jugular vein as a single IV bolus (group 2), or 3 times as IV boluses repeated at 10-minute intervals (group 3). Dose-response curves in group 1 indicated a biphasic response to the drug with vasoconstriction, increased motility, and increased oxygen consumption at lower doses followed by a return toward base-line values at higher doses. Intestinal compliance decreased at lower doses, but increased at higher doses. A single IV bolus of xylazine (group 2) induced systemic hypotension for 30 minutes, and increased intestinal vascular resistance for 10 minutes accompanied by increased motility, and repeatedly administered IV boluses of xylazine (group 3) increased and prolonged these effects. The results indicated that xylazine, especially in repeated doses, may decrease bowel viability by simultaneously increasing intestinal vascular resistance, motility, and oxygen consumption.

Animals↗
PubMed1986

Comparison of three feeding techniques after esophageal mucosal resection and anastomosis in the horse.

The effects of 3 feeding techniques on healing of a cervical esophageal mucosal resection and anastomosis were investigated in 16 horses. Horses were fed a moistened pelleted diet 1 of 3 ways: 1) per os (n = 5), 2) by nasogastric (n = 5) or 3) by esophagostomy tube (n = 6) until the 14th postoperative day. The pelleted diet was then fed orally in all horses until euthanasia on the 60th postoperative day. Immediate postoperative feeding per os was unsatisfactory, as only 2 of 5 horses survived in this group. Endoscopic evaluation revealed that mucosal dehiscence of varying degrees occurred, with subsequent stricture formation in all horses. Although the incidence of some complications (fistula, sinus tract and traction diverticulum) was higher in the nasogastric tube-fed horses, 2 of 6 horses in the esophagostomy tube-fed group did not survive to the end of the study. There was more cervical phlegmon in the esophagostomy tube-fed group, and this resulted in increased periesophageal fibrosis on histopathologic examination. Radiographic measurements showed that esophageal lumen diameter increased predominantly between 30 and 45 days postoperatively. The mucosal healing time was significantly faster (p = 0.05) in the esophagostomy tube-fed group.

Animals↗
PubMed1986

Effect of laryngeal hemiplegia and laryngoplasty on airway flow mechanics in exercising horses.

The effect of left laryngeal hemiplegia on airway flow mechanics in 5 exercising horses was examined, and the efficacy of surgical repair by prosthetic laryngoplasty was evaluated. Measurements of the upper airway flow mechanics were made with horses on a treadmill (incline 6.38 degrees) while standing (period A); walking at 1.3 m/s (period B); trotting at 2.6 m/s (period C); trotting at 4.3 m/s (period D); and standing after exercise (period E). Experiments were done on healthy horses before any surgical manipulation (control), at 10 days after left recurrent laryngeal neurectomy, and at least 14 days after prosthetic larynogoplasty. Increasing treadmill speed from period A to period D progressively increased heart rate, respiratory frequency, peak inspiratory flow, and peak expiratory flow, but inspiratory resistance and expiratory resistance remained unchanged. Neither left recurrent laryngeal neutrectomy nor prosthetic laryngoplasty affected heart rate, respiratory frequency, peak expiratory flow, or expiratory resistance when compared with those values at the control measurement periods. Left recurrent laryngeal neurectomy resulted in inspiratory flow limitation at peak inspiratory flow of approximately 25 L/s, and increased inspiratory resistance at periods D and E. Subsequent prosthetic laryngoplasty alleviated the flow limitation and reduced inspiratory resistance at measurement periods D and E.

Animals↗
PubMed1985

Airway reactivity in ponies with recurrent airway obstruction (heaves).

We measured lung function and airway reactivity to histamine administered by aerosol in two groups of ponies. Principal ponies had a history of heaves, a disease characterized by recurrent airway obstruction when ponies are housed in a barn and fed hay; control ponies had no history of airway obstruction. Ponies were paired (principal and control) and measurements were made when principal ponies were at pasture and in clinical remission (period A), following barn housing when principal ponies had acute airway obstruction (period B), and after a further 1 and 2 wk at pasture (periods C and D). At periods A, C, and D dynamic compliance (Cdyn), pulmonary resistance (RL), arterial O2 tension (PaO2), and CO2 tension (PaCO2) of principals and controls did not differ. Barn housing (period B) decreased Cdyn and PaO2 and increased RL in principals but not controls. The ED65Cdyn (the dose of histamine to reduce Cdyn to 65% of base line) did not differ in principals and controls at periods A, C, and D. At period B, ED65Cdyn decreased by 2.5-log doses of histamine in principals while ED65Cdyn was not affected in controls. There was no correlation between changes in airway reactivity and changes in RL and Cdyn. We conclude that ponies in clinical remission from heaves are not hyperreactive to histamine aerosol. This model of lung disease is similar to some forms of industrial asthma in which hyperreactivity occurs only during acute airway obstruction. The lack of correlation between ED65Cdyn and the degree of airway obstruction suggests that the hyperreactivity of principal ponies to histamine aerosol cannot be explained solely by alterations in baseline airway caliber.

Animals↗
PubMed1984

Medical management of esophageal stricture in seven horses.

Esophageal strictures developed in 7 horses that were treated for esophageal obstruction. A soft diet was fed to all horses, with intermittent nasogastric tube feeding in one, and medication included nonsteroidal anti-inflammatory drugs. Maximal reduction in esophageal lumen diameter was evident by 30 days following circumferential esophageal ulceration, after which lumen diameter increased rapidly. Five horses were clinically normal by 60 days after the esophageal injury. Two horses were euthanatized at the owner's request, 16 and 17 days after the original insult.

Airway Obstruction↗
PubMed1983

Esophagotomy in the pony: comparison of surgical techniques and form of feed.

Esophageal healing was studied in 12 ponies after cervical esophagotomy. The esophagus was sutured, feed and water were withheld for 48 hours, and then all ponies were permitted to eat. In group I (n = 6), a longitudinal esophagotomy was made. In group II (n = 6), a rotational esophagotomy was made with the mucosal incision 180 degrees away from the incision in the esophageal muscle. Three ponies in each group were fed a soft diet ad libitum for 9 days, and then were allowed access to hay and grain. The remaining ponies were fed hay and grain. The esophagotomies of all hay-fed ponies dehisced and healed by second intention, whereas esophagotomies healed by first intention in the ponies given a soft diet. Endoscopic and radiographic examinations indicated that the progression of healing in the present study was a function of diet (form of food), rather than surgical technique. The cross-sectional width of the muscularis externa at the incision site was 39.6% greater in mash-fed ponies than in hay-fed ponies. Based on density-dependent image analysis, average elastin content and reticulin fiber of the submucosa and muscularis externa at the incision were not influenced by the form of feed or surgical technique, although elastin fiber regeneration did not occur at the site of the incision.

Animal Feed↗
PubMed1983

Equine esophageal pressure profile.

Esophageal motility was studied in 5 healthy adult horses, using a 4 side-hole catheter assembly continuously perfused with distilled water. Resting pressure and maximal pressures generated during swallowing were measured over the whole length of the esophagus (mean +/- S means = 132.7 +/- 2.31 cm). Four functionally distinct regions of the esophagus were demonstrated: cranial esophageal sphincter, caudal esophageal sphincter, and "fast" and "slow" regions in the body of the esophagus. The resting pressure of the cranial and caudal esophageal sphincters were 171.1 +/- 20.45 (x +/- S means) and 10.5 +/- 0.61 (x +/- S means) mm of Hg, respectively. The maximal pressure of the "fast" and the "slow" esophageal regions and caudal esophageal sphincter were 63.1 +/- 3.75 (x +/- S means), 71.9 +/- 3.65 (x +/- S means), and 63.1 +/- 2.60 (x +/- S means) mm of Hg, respectively. The length of each region and duration of pressure events were quantitated, establishing an equine esophageal pressure profile.

Animals↗
PubMed1982

Pedal bone rotation as a prognostic sign in laminitis of horses.

We reviewed 91 cases of laminitis in horses admitted to the Michigan State University Veterinary Clinical Center between Jan 1, 1973 and Dec. 30, 1978. From information in the case records and from the results of a telephone questionnaire, cases were classified into 4 categories on the basis of return to athletic function. The degree of pedal bone rotation was inversely correlated with return to athletic performance. Horses with less than 5.5 degrees rotation returned to former athletic function, whereas horses with more than 11.5 degrees rotation lost their use as performance animals. Ponies had significantly more pedal bone rotation, when compared with horses.

Animals↗
PubMed1982

Quantitative ultrastructural anatomy of esophagus in different regions in the horse: effects of alternate methods of tissue processing.

A qualitative and quantitative study was made of 2 adult horses to determine the effect of specimen preparation and the influence of anatomically separate regions on the microscopic structure of the esophagus. The effects of 3 fixative solutions (formalin, Bouin's fixative and Karnovsky's fixative) and 4 histologic staining procedures (hematoxylin and eosin, Gomori's trichrome, Laidlow's reticulum, and orcein-elastin) were compared. Density-dependent image analysis was used to compare the relative contributions of elastic and reticular fibers in esophageal connective tissue for each region. Cross-sectional dimensions of the tissue layers which comprise the esophageal wall were obtained by light microscopic measurement and were compared for each region. The mucosal surface structure was examined by scanning electron microscopy. Our results indicate that specimen preparation has significant effects on the structural integrity of esophageal tissues. Bouin's fixative was inferior to the other fixatives in this regard. Furthermore, there are extensive regional differences in esophageal microstructure. Formalin-fixed tissues stained with either hematoxylin and eosin or Gomori's trichrome appear the most suitable for routine quantitative morphologic studies of the equine esophagus.

Acetates↗
PubMed1981

Equine cervical esophagostomy: complications associated with duration and location of feeding tubes.

Cervical esophagostomy for tube feeding was evaluated in 11 ponies. Minor complications responded to supportive therapy in 8 ponies. Two died of complications, and 1 pony had a permanent fistula because of persistent infection. There was a positive correlation between the duration of tube feeding and the event of closure of the esophageal stoma after the tube was removed. There was no difference in the frequency of complications related to duration of tube feeding. When the distal end of the feeding tube was located in the thoracic portion of the esophagus, instead of in the stomach, tubes were more readily dislodged. Reinsertion of some tubes was difficult or impossible to do and resulted in false passage of the tube into the mediastinal space, dissecting infections into the thorax, or both. Reflux of food around the tube occurred in ponies with the distal end of the feeding tube located in the stomach, but this was not associated with other complications.

Animals↗
PubMed1981

Acid-base and electrolyte alterations associated with salivary loss in the pony.

Esophageal fistulas were made in 6 ponies to evaluate whole blood acid-base values and serum and salivary electrolyte alterations associated with salivary depletion. Acid-base and electrolyte values remained within normal ranges for 15 days in 3 control ponies fed a pelleted diet through nasogastric tubes. In 6 ponies with esophageal fistulas that were fed the same diet through esophagostomy tubes, hypochloremia and hyponatremia developed during the same period. Serum K concentrations were only marginally depleted, probably because of dietary replacement. Salivary depletion resulted in transient metabolic acidosis from bicarbonate lost in saliva followed by progressive metabolic alkalosis. The alkalosis probably resulted from renal compensation of electrolyte imbalances. Salivary electrolytes were in high concentrations, probably because of increased salivary flow rates. Initial saliva was rich in Na, Cl, and K, but progressive reduction in salivary Na and Cl concentrations occurred during the 5-day collection period. These electrolyte savings could be explained by dietary influences and hormonal control of electrolyte transport in salivary ducts. Therapy for correction of acid-base and electrolyte alterations was also discussed.

Acid-Base Imbalance↗
PubMed1981

Esophageal healing in the pony: comparison of sutured vs nonsutured esophagotomy.

Esophageal healing was evaluated in 10 ponies after sutured and nonsutured cervical esophagotomy techniques. Mucosal healing occurred significantly (P less than 0.005) faster after sutured esophagotomies (x = 7.5 days after surgery) than after nonsutured esophagotomies (x = 25.6 days after surgery), based on endoscopic and clinical evaluations. Although endoscopy was an accurate assessment of the return of normal passage of a food bolus through the esophagus, 4 of 10 ponies had radiographic evidence of a sinus tract after the mucosa was considered healed, based on endoscopic and clinical examinations. The surgical skin wound also healed significantly sooner after sutured esophagotomies (x = 10 days) than after nonsutured esophagotomies (x = 33.4 days). A traction diverticulum developed in all ponies with nonsutured esophagotomies, but occurred in only 1 pony with sutured esophagotomy. Minor complications were seen more frequently with sutured esophagotomy than with a nonsutured esophagotomy, but were resolved with local therapy. Saliva appeared to inhibit wound healing. All ponies were fed through esophagostomy tubes until the mucosa at the esophagotomy site was considered healed. Except for 1 sutured esophagotomy that dehisced, sutured esophagotomy was superior to nonsutured esophagotomy, because earlier establishment of a mucosal seal resulted in more rapid healing and reduced nursing care.

Animals↗
PubMed1981

Technique for reversible vagal blockade in the standing conscious pony.

A surgical technique is described for preparation of chronic cervical vagal loops in ponies. Vagal blockade was induced by circulating methanol (-2 C) through coils which enclosed the loops. Vagal blockade increased tidal volume, heart rate, and systemic blood pressure and decreased respiratory rate. Atropine, given at a dose of 0.04 mg/kg IV, increased heart rate and systemic pressure but did not alter respiratory variables, indicating that vagal cooling caused both afferent and efferent blockade. The effects of vagal blockade were rapidly reversed when refrigerated coils were removed.

Animals↗
PubMed1980

Subepiglottic cyst in three foals.

Three foals with chronic cough, bilateral nasal discharge, and pneumonia were found to have a subepiglottic cyst as the inciting cause. Consistent findings were dysphagia and aspiration pneumonia, in addition to the abnormal respiratory noise usually found in the adult horse with a subepiglottic cyst. Histologic examination of the cysts suggested their origin was traumatic rather than embryonic.

Animals↗