THE USE OF A BARIUM MEAL TO EVALUATE TOTAL GASTRIC EMPTYING TIME IN THE DOG

Functional and anatomical gastric regions and their relations to motility control

The common occurrence of gastric disorders, the accelerating emphasis on the role of the gut-brain axis, and development of realistic, predictive models of gastric function, all place emphasis on increasing understanding of the stomach and its control. However, the ways that regions of the stomach have been described anatomically, physiologically, and histologically do not align well. Mammalian single compartment stomachs can be considered as having four anatomical regions fundus, corpus, antrum, and pyloric sphincter. Functional regions are the proximal stomach, primarily concerned with adjusting gastric volume, the distal stomach, primarily involved in churning and propelling the content, and the pyloric sphincter that regulates passage of chyme into the duodenum. The proximal stomach extends from the dome of the fundus to a circumferential band where propulsive waves commence (slow waves of the pacemaker region), and the distal stomach consists of the pacemaker region and the more distal regions that are traversed by waves of excitation, that travel as far as the pyloric sphincter. Thus, the proximal stomach includes the fundus and different extents of the corpus, whereas the distal stomach consists of the remainder of the corpus and the antrum. The distributions of aglandular regions and of specialized glands, such as oxyntic glands, differ vastly between species and, across species, have little or no relation to anatomical or functional regions. It is hoped that this review helps to clarify nomenclature that defines gastric regions that will provide an improved basis for drawing conclusions for different investigations of the stomach.

Validation of Ultrasonography for Assessment of Gastric Emptying Time in Healthy Cats by Radionuclide Scintigraphy

Background

The prevalence of gastric emptying (GE) disorders in cats is unknown due to lack of clinically applicable diagnostic tests.

Objectives

The principal aim of this study was to assess correlation between scintigraphic and ultrasonographic measurements of GE time (GET) in healthy cats. Additionally, variability of ultrasonographic GET, and correlation between scintigraphy and ultrasonographic parameters of gastric motility were evaluated.

Animals

Eight healthy domestic shorthair cats.

Methods

Prospective study. Scintigraphic GET was determined using a solid test meal containing 4 mCi ^99mTc‐mebrofenin. Each cat had 3 separate ultrasonographic assessments of GE, performed independent of scintigraphic assessment, after solid test meal consumption. The motility index (MI) of antral contractions was plotted against time and time for each fraction of the area under the MI curve determined. Ultrasonographic GET and MI were correlated to scintigraphic GET.

Results

Scintigraphic GET (mean ± SD) for 25, 50, and 75% GE was 103 ± 32 minutes, 196 ± 45 minutes, and 288 ± 62 minutes, whereas sonographic GET for 25, 50, and 75% GE was 106 ± 13 minutes, 203 ± 19 minutes, and 305 ± 27 minutes. There was good correlation between scintigraphic and sonographic GET (r = 0.72–0.82) at 45–90% fractional GE and between scintigraphic GET and time of corresponding MI curve fraction (r = 0.78–0.86) at 40–90% fraction of the MI curve. There was moderate intraindividual variability for sonographic GET and MI curve fraction times as well as significant variation among individuals.

Conclusions and clinical importance

Ultrasonography is a valid alternative to scintigraphy for assessment of solid‐phase GE and allows assessment of postprandial gastric motility in healthy cats.

Evaluation of computed tomographic enterography with an orally administered lactulose solution in clinically normal dogs

OBJECTIVE

To determine optimal techniques for CT enterography in clinically normal dogs and to evaluate luminal distention after oral administration of lactulose solution as a contrast agent.

ANIMALS

15 healthy dogs.

PROCEDURES

CT was performed in a control group (2 dogs that underwent CT to evaluate metastasis and 5 other dogs). In a bolus administration group (5 dogs from the control group), lactulose solution (1.34 g/mL) was administered (60 mL/kg) rapidly via gastric tube to anesthetized dogs, and CT was performed every 10 minutes for 1 hour. In a continuous administration group of 8 other dogs, lactulose solution (60 mL/kg) was administered slowly via nasoesophageal tube over a period of 45 minutes. Then, 15 minutes after anesthetic induction, CT was performed every 10 minutes for 1 hour. Luminal distention of the small intestines was evaluated qualitatively by use of a 3-point scale.

RESULTS

All small intestinal segments had poor luminal distention in the control group. The terminal ileum had poor luminal distention for the bolus administration group. Nearly all segments had good luminal distention for the continuous administration group with mild adverse effects. Luminal distention scores from 0 to 20 minutes after lactulose administration were significantly higher than scores from 30 to 60 minutes. Interobserver reproducibility was high for all intestinal segments.

CONCLUSIONS AND CLINICAL RELEVANCE

CT performed between 0 and 20 minutes after continuous administration of lactulose solution (60 mL/kg) may reveal adequate luminal distention for examination of small intestinal segments in dogs.

Gastrointestinal dysmotility disorders in critically ill dogs and cats

OBJECTIVE

To review the human and veterinary literature regarding gastrointestinal (GI) dysmotility disorders in respect to pathogenesis, patient risk factors, and treatment options in critically ill dogs and cats.

ETIOLOGY

GI dysmotility is a common sequela of critical illness in people and small animals. The most common GI motility disorders in critically ill people and small animals include esophageal dysmotility, delayed gastric emptying, functional intestinal obstruction (ie, ileus), and colonic motility abnormalities. Medical conditions associated with the highest risk of GI dysmotility include mechanical ventilation, sepsis, shock, trauma, systemic inflammatory response syndrome, and multiple organ failure. The incidence and pathophysiology of GI dysmotility in critically ill small animals is incompletely understood.

DIAGNOSIS

A presumptive diagnosis of GI dysmotility is often made in high-risk patient populations following detection of persistent regurgitation, vomiting, lack of tolerance of enteral nutrition, abdominal pain, and constipation. Definitive diagnosis is established via radioscintigraphy; however, this diagnostic tool is not readily available and is difficult to perform on small animals. Other diagnostic modalities that have been evaluated include abdominal ultrasonography, radiographic contrast, and tracer studies.

THERAPY

Therapy is centered at optimizing GI perfusion, enhancement of GI motility, and early enteral nutrition. Pharmacological interventions are instituted to promote gastric emptying and effective intestinal motility and prevention of complications. Promotility agents, including ranitidine/nizatidine, metoclopramide, erythromycin, and cisapride are the mainstays of therapy in small animals.

PROGNOSIS

The development of complications related to GI dysmotility (eg, gastroesophageal reflux and aspiration) have been associated with increased mortality risk. Institution of prophylaxic therapy is recommended in high-risk patients, however, no consensus exists regarding optimal timing of initiating prophylaxic measures, preference of treatment, or duration of therapy. The prognosis for affected small animal patients remains unknown.

Associations between meal size, gastric emptying and post-prandial plasma glucose, insulin and lactate concentrations in meal-fed cats

Plasma glucose and insulin concentrations are increased for 12-24 h in healthy cats following moderate- to high-carbohydrate meals. This study investigated associations between gastric emptying time and post-prandial plasma glucose, insulin and lactate concentrations in cats fed an extruded dry, high-carbohydrate, moderate-fat, low-protein diet (51, 28, 21% metabolizable energy, respectively) once daily by varying meal volume. Eleven healthy, non-obese, neutered adult cats were enrolled in a prospective study and fed to maintain body weight. Ultrasound examinations were performed for up to 26 h, and blood collections over 24 h after eating meals containing approximately 100% and 50% of the cats' daily caloric intake (209 and 105 kJ/kg BW, respectively). Gastric emptying time was increased after a meal of 209 kJ/kg BW compared with 105 kJ/kg BW (median gastric emptying times 24 and 14 h, respectively; p = 0.03). Time for glucose to return to fasting was longer after the 209 kJ/kg BW meal (median 20 h; 25th and 75th percentiles 15 and 23 h, respectively) than the 105 kJ/kg BW meal (13, 12 and 14 h; p < 0.01); however, peak glucose was not higher after the 209 kJ/kg BW meal compared with the 105 kJ/kg BW meal [(mean ± SD) 6.6 ± 0.6 and 7.8 ± 1.2 mmol/l, respectively, p = 0.07]. Times for insulin to return to fasting were not significantly longer after the 209 kJ/kg BW meal than the 105 kJ/kg BW meal (p = 0.29). d- and l-lactate concentrations were not associated with gastric emptying time or post-prandial blood glucose and insulin. Based on results obtained, prolonged gastric emptying contributes to prolonged post-prandial hyperglycemia in cats meal fed a high-carbohydrate, low-protein, dry diet and fasting times for cats' meal-fed diets of similar composition should be 14-26 h, depending on meal size.

Imaging diagnosis-pulmonary-tracheobronchial prolapse in a new Caledonian giant gecko (Rhacodactylus leachianus)

A 3-year-old male New Caledonian giant gecko, or Leach's gecko (Rhacodactylus leachianus) presented with acute lethargy and coelomic distention. Findings from survey radiographs and an upper gastrointestinal tract contrast study were consistent with severe aerophagia, a collapsed left lung, and hyperinflation of the right lung due to suspected bronchial obstruction. The gecko was treated with conservative medical management, but was found dead 5 days after presentation. Necropsy findings showed intussusception of the proximal left lung into the left mainstem bronchus and trachea.

Assessment of the variation associated with repeated measurement of gastrointestinal transit times and assessment of the effect of oral ranitidine on gastrointestinal transit times using a wireless motility capsule system in dogs

This study aimed to evaluate the variation associated with repeated measurement of gastrointestinal (GI) transit times and the effect of oral ranitidine on GI transit times in healthy dogs using a wireless motility capsule (WMC) system. Eight privately owned healthy adult dogs were enrolled, and one developed diarrhea and was removed from the study. For the first 3 repetitions, each dog was fed a standard meal followed by oral administration of a WMC. For the 4th repetition, each dog was given ranitidine hydrochloride (75 mg PO every 12 hours) prior to and during assessment of GI transit times. Mean between-subject coefficients of variation for gastric emptying time (GET), small and large bowel transit time (SLBTT), and total transit time (TTT) were 26.9%, 32.3%, and 19.6%, respectively. Mean within-subject coefficients of variation for GET, SLBTT, and TTT were 9.3%, 19.6%, and 15.9%, respectively. Median GET, SLBTT, and TTT without ranitidine were 719, 1,636, and 2,735 minutes, respectively. Median GET, SLBTT, and TTT with ranitidine were 757, 1,227, and 2,083 minutes, respectively. No significant differences in GI transit times were found between any of the 4 repetitions. Under these experimental conditions, no significant effects of oral ranitidine on GI transit times were observed.

Assessment of the relationship between body weight and gastrointestinal transit times measured by use of a wireless motility capsule system in dogs

OBJECTIVE

To assess the relationship between body weight and gastrointestinal transit times measured by use of a wireless motility capsule (WMC) system in healthy dogs.

ANIMALS

31 healthy adult dogs that weighed between 19.6 and 81.2 kg.

PROCEDURES

Food was withheld overnight. The following morning, a WMC was orally administered to each dog, and each dog was then fed a test meal that provided a fourth of the daily energy requirements. A vest was fitted on each dog to hold a receiver that collected and stored data from the WMC. Measurements were obtained with each dog in its home environment. Regression analysis was used to assess the relationship between body weight and gastrointestinal transit times.

RESULTS

Gastric emptying time (GET) ranged from 405 to 897 minutes, small bowel transit time (SBTT) ranged from 96 to 224 minutes, large bowel transit time (LBTT) ranged from 427 to 2,573 minutes, and total transit time (TTT) ranged from 1,294 to 3,443 minutes. There was no positive relationship between body weight and gastrointestinal transit times. A nonlinear inverse relationship between body weight and GET and between body weight and SBTT best fit the data. The LBTT could not be explained by this model and likely influenced the poor fit for the TTT.

CONCLUSIONS AND CLINICAL RELEVANCE

A positive relationship did not exist between body weight and gastrointestinal transit times. Dogs with the lowest body weight of the cohort appeared to have longer gastric and small intestinal transit times than did large- and giant-breed dogs.

Variability associated with repeated measurements of gastrointestinal tract motility in dogs obtained by use of a wireless motility capsule system and scintigraphy

OBJECTIVE

To compare repeatability of measurements of gastrointestinal tract motility in healthy dogs obtained by use of a wireless motility capsule (WMC) and scintigraphy.

ANIMALS

6 healthy adult dogs (mean +/- SD body weight, 21.5 +/- 1.8 kg).

PROCEDURES

A radiolabeled test meal was offered immediately after oral administration of a WMC. Serial static scintigraphic abdominal images were acquired for 270 minutes. A dedicated remote receiver was used for data collection from the WMC until the WMC was expelled in the feces. Each dog was evaluated 3 times at intervals of 1 to 2 weeks.

RESULTS

Mean gastric emptying half-time measured by use of scintigraphy (T(1/2)-GES) for each dog ranged from 99.9 to 181.2 minutes. Mean gastric emptying time (GET) measured by use of the WMC (GET-WMC) in each dog ranged from 385.3 to 669.7 minutes. Mean coefficient of variation was 11.8% for T(1/2)-GES and 7.8% for GET-WMC. The intraclass correlation coefficient was 69% for T(1/2)-GES and 71% for GET-WMC. Results for a nested analysis of covariance suggested that both methods were comparable for the evaluation of gastric emptying.

CONCLUSIONS AND CLINICAL RELEVANCE

Scintigraphy and a WMC system had similar variation for assessment of gastric emptying. Moderate intraindividual variability was detected for both methods and must be considered when interpreting test results for individual dogs. Repeatability of measurements obtained by use of the WMC was equivalent to that obtained by use of scintigraphy. The WMC system offers a nonradioactive, user-friendly method for assessment of gastric emptying in dogs.

Long-term Measurement of Gastric Motility using Passive Telemetry and Effect of Guar and Cellulose as Food Additives in Dogs

The suitability of passive telemetry for long-term measurements of gastric motility in two groups of dogs with different body weights, four Beagles and four Labrador Retrievers, was investigated. An intra-abdominal measuring device, with a pressure sensor and electrodes within the gastric wall, allowed the continuous recording of the intensity and frequency of contractions simultaneously with an electromyogram (EMG). In fasting dogs a typical inter-digestive motility cycle was reproducible. Within 15 min of feeding the integral of the pressure curve increased significantly, reaching its maximum 30-45 min post-prandially. The peak frequency also significantly increased immediately after feeding, reaching the maximum of 22 contractions per 5 min. The post-prandial motility patterns of the groups were significantly different. The pressure amplitudes of the Labradors were significantly higher and the peak frequencies significantly lower than the Beagles. The addition of guar to the food (2.5% or 5%) leads to a significant reduction of the intensity of the antral contractions, whereas the frequency was hardly affected. In comparison, the effect of cellulose, as a food additive (2.5% or 5%), was rather modest. The intensity of the post-prandial contractions, influenced by cellulose, was significantly increased in Beagles, but was decreased in Labradors. Passive telemetry has been proven to be a suitable method for the long-term investigation of the physiological gastric motility and the effect of food additives. The measuring device was still functional after removal 8 weeks later.

Comparison of the effect of laparoscopic and conventional pyloric surgery on gastric emptying in dogs

The effect of a laparoscopic approach and pyloric surgery on canine gastrointestinal activity, particularly gastric emptying time, is not well understood. The purpose of this study was to compare the effect of laparoscopic and conventional pyloric surgery, in Ramstedt pyloromyotomy and Heineke-Mikulicz pyloroplasty, on complete gastric emptying time in 20 clinically normal dogs. Dogs were divided into four groups of five animals: dogs with laparoscopic Ramstedt pyloromyotomy, conventional Ramstedt pyloromyotomy, or laparoscopic Heineke-Mikulicz pyloroplasty, and the conventional Heineke-Mikulicz pyloroplasty group. Gastric emptying time using barium sulfate mixed with dry kibble dog food was measured fluoroscopically before and 1 month after surgery. Gastric emptying of solids was significantly enhanced in the pyloroplasty groups in the postoperative period compared with preoperative emptying. Just as after conventional pyloromyotomy, gastric emptying time after laparoscopic pyloromyotomy was not statistically different as compared with preoperative values. This study indicates that the fluoroscopic test meal is a valuable tool for defining complete gastric emptying time in normal dogs. We conclude that pyloromyotomy was less effective in decreasing complete gastric emptying time than Heineke-Mikulicz pyloroplasty in normal dogs. The possibility of decreasing complete gastric emptying time by laparoscopic surgery suggests a potential clinical application for this technique in small animals.

Effect of body size on gastric emptying using the 13C-octanoic acid breath test

The 13C-octanoic acid breath test (OABT) may be a useful non-invasive method for assessing the rate of gastric emptying in dogs. The aim of this study was to determine whether an association exists between body size and rate of gastric emptying in dogs. Fifty-five dogs ranging from 6 to 39 kg were recruited and rate of gastric emptying was assessed using the OABT. The time to peak 13CO2 excretion (tmax) and half-dose recovery time (t1/2) were calculated. The OABT was simple to perform and well tolerated by the dogs. Mean (sd) tmax was 2.67 hours (0.6) and mean t1/2 was 3.38 hours (0.79). Inter-individual variation in the rate of gastric emptying was 23.3 per cent for t1/2 and 22.5 per cent for tmax. No association was detected between the rate of gastric emptying and body surface area, mass, age, sex or test operator. The OABT may be a useful non-invasive and non-radioactive test for assessment of the rate of gastric emptying in dogs in clinical practice.

A review of methods for assessment of the rate of gastric emptying in the dog and cat: 1898-2002

Gastric emptying is the process by which food is delivered to the small intestine at a rate and in a form that optimizes intestinal absorption of nutrients. The rate of gastric emptying is subject to alteration by physiological, pharmacological, and pathological conditions. Gastric emptying of solids is of greater clinical significance because disordered gastric emptying rarely is detectable in the liquid phase. Imaging techniques have the disadvantage of requiring restraint of the animal and access to expensive equipment. Radiographic methods require administration of test meals that are not similar to food. Scintigraphy is the gold standard method for assessment of gastric emptying but requires administration of a radioisotope. Magnetic resonance imaging has not yet been applied for assessment of gastric emptying in small animals. Ultrasonography is a potentially useful, but subjective, method for assessment of gastric emptying in dogs. Gastric tracer methods require insertion of gastric or intestinal cannulae and are rarely applied outside of the research laboratory. The paracetamol absorption test has been applied for assessment of liquid phase gastric emptying in the dog, but requires IV cannulation. The gastric emptying breath test is a noninvasive method for assessment of gastric emptying that has been applied in dogs and cats. This method can be carried out away from the veterinary hospital, but the effects of physiological and pathological abnormalities on the test are not known. Advances in technology will facilitate the development of reliable methods for assessment of gastric emptying in small animals.

Evaluation of canine gastric motility with ultrasonography

For the evaluation of canine gastric motility with ultrasonography, contraction number of pyloric antrum and gastric emptying time (GET) by area and volume method developed by Bolondi et al.'s method were studied in 14 dogs. All experimental dogs were administered with saline and soup solution (10 ml/kg, B.W.). The mean values of contraction number of pyloric antrum in saline and soup group were 4.19 +/- 1.30/min and 4.82 +/- 0.65/min before feeding, and overall mean values were 4.66 +/- 1.37/min and 5.13 +/- 1.71/min, respectively. The mean values of the GET by area and volume method were 36.73 +/- 11.27, 40.00 +/- 8.87 min in saline group and 61.35 +/- 17.58, 59.11 +/- 14.46 min in soup group. In the GET in saline and soup groups, there was no significant difference between the area and volume method (p>0.05). Therefore, Bolondi et al.'s method by ultrasound can be used to evaluate the antropyloric motility and gastric emptying time with area and volume methods. The area method is easier to determine the GET than the volume method, but the latter is more accurate.

Use of the 13C-octanoic acid breath test for assessment of solid-phase gastric emptying in dogs

OBJECTIVE

To assess the 13C-octanoic acid breath test for determining gastric emptying in dogs.

ANIMALS

6 healthy adult dogs.

PROCEDURE

Food was withheld for 12 hours before each test. Expired air was collected 30 minutes and immediately before each test and at frequent intervals thereafter for 6 hours. Concentration of 13CO2 in expired air was determined by use of continuous-flow isotope-ratio mass spectrometry. Basal concentration of 13CO2 was measured in dogs that were not fed a test meal. Effects of the standard unlabeled test meal on basal concentration of 13CO2 were then assessed. The optimum dose of substrate was determined by measuring 13CO2 concentration after ingestion of the standard test meal containing 50 or 100 mg of 13C-octanoic acid, whereas effect of energy density of the test meal on gastric emptying was determined after ingestion of the standard or high-energy labeled test meal. Gastric emptying coefficient (GEC), time to peak 13CO2 concentration (tmax), and half-dose recovery time (t(1/2)) were calculated.

RESULTS

Basal concentration of 13CO2 in expired air was not significantly affected by ingestion of the unlabeled test meal. However, 13CO2 concentration significantly increased in a dose-dependent manner after ingestion of the labeled meal. Gastric emptying coefficient, and were significantly different between dogs fed the standard and high-energy test meals, indicating that ingestion of a high-energy meal delays gastric emptying.

CONCLUSIONS AND CLINICAL RELEVANCE

The 13C-octanoic acid breath test may be a useful noninvasive and nonradioactive method for assessment of gastric emptying in dogs.

Assessment of barium impregnated polyethylene spheres (BIPS) as a measure of solid-phase gastric emptying in normal dogs--comparison to scintigraphy

Barium impregnated polyethylene spheres (BIPS) are radiopaque markers used for investigation of a variety of gastrointestinal disorders. One proposed use of the small (1.5 mm) marker is quantitative assessment of solid-phase gastric emptying, which may offer a simple, inexpensive alternative to nuclear medicine studies. In this study the rate and pattern of gastric emptying of a radiolabeled meal containing 30 small BIPS was evaluated in normal dogs by simultaneous comparison of the radiopaque marker method and a scintigraphic method. Serial scintigraphic images and radiographs were obtained for 8 hours or until 95% of the markers had left the stomach. Emptying curves were constructed and statistical analyses performed. There were significant differences in gastric emptying times and lag phase characteristics between the BIPS and scintigraphic studies. These results indicate that in normal dogs there are differences in both the rate and the pattern of solid-phase gastric emptying of a radiolabeled meal as assessed by scintigraphy and the gastric emptying of small BIPS.