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.     

Determination of solid- and liquid-phase gastric emptying half times in cats by use of nuclear scintigraphy

OBJECTIVE: To use nuclear scintigraphy to establish a range of gastric emptying half times (t1/2) following a liquid or solid meal in nonsedated cats. ANIMALS: 12 clinically normal 3-year-old domestic shorthair cats. PROCEDURE: A test meal of 75 g of scrambled eggs labeled with technetium Tc 99m tin colloid was fed to 10 of the cats, and solid-phase gastric emptying t1/2 were determined by use of nuclear scintigraphy. In a separate experiment, 8 of these cats plus an additional 2 cats were fed 18 ml (n = 5) or 36 ml (n = 5) of a nutrient liquid meal labeled with technetium Tc 99m pentetate. Liquid-phase gastric emptying t1/2 then were determined by use of scintigraphy. RESULTS: Solid-phase gastric emptying t1/2 were between 210 and 769 minutes (median, 330 minutes). Median liquid-phase gastric emptying t1/2 after ingestion of 18 or 36 ml of the test meal were 67 minutes (range, 60 to 96 minutes) and 117 minutes (range, 101 to 170 minutes), respectively. The median t1/2 determined for cats receiving 18 ml of the radiolabeled liquid was significantly less than that determined for cats receiving 36 ml of the test meal. CONCLUSIONS AND CLINICAL RELEVANCE: The protocol was tolerated by nonsedated cats. Solid-phase gastric emptying t1/2 were prolonged, compared with liquid-phase t1/2, and a major factor governing the emptying rate of liquids was the volume consumed. Nuclear scintigraphy may prove useful in assessing gastric motility disorders in cats.     

The(13)C-octanoic acid breath test for detection of effects of meal composition on the rate of solid-phase gastric emptying in ponies

The aim of this study was to apply the(13)C-octanoic acid breath test for detection of alterations in the rate of solid-phase gastric emptying, induced by changes in test meal composition, in ponies. After a 14 hour fast the ponies (n = 4) ingested a test meal with 0, 35 or 70 ml soya oil, and labelled with 250 mg(13)C-octanoic acid. Each pony was given each of the three test meals on three separate occasions, in a randomised order. Exhaled breath samples were collected for 12 hours after ingestion of the test meal. Breath samples were analysed by continuous flow isotope ratio mass spectrometry. Three indices of breath(13)C-enrichment were computed, half-dose recovery time (t 1/2), gastric emptying coefficient (GEC) and time to peak breath(13)C-excretion t(max). The(13)C-octanoic acid breath test was a reliable means of assessing the significantly decreased rate of gastric emptying in the pony, associated with addition of soya oil to the test meal.     

Influence of dietary composition on gastric emptying and motility in dogs: potential involvement in acute gastric dilatation

Gastric dilatation-volvulus is a dramatic and life-threatening disease of large-breed dogs. The cause is unknown, but ingestion of dry cereal-based food is frequently incriminated as a predisposing factor. The purpose of this study was to examine the effect of commercial diets on gastric motility and emptying in the dog. Four large-breed dogs were fed 3 different diets (diet A = canned meat-based; B = cereal-based with 77% added water; and C = dry cereal-based) in a randomized block design. Each experiment was done in triplicate. Motility was assessed, using 5 AgAgCl electrodes and 2 strain gauges sutured along the serosa of the stomach and proximal duodenum. Dogs were fed at the same time each day and the time to change from the fed to the fasted pattern of gastrointestinal motility (changeover) was measured. Gastric emptying was assessed by recording gastric radioactivity. After feeding a meal mixed with 99mTc-labeled resin, the log of activity was plotted against time, and the half-time of gastric emptying (t1/2 GE) was calculated. Mean (+/- SEM) times from feeding to changeover for the 3 diets were: diet A, 9.7 +/- 0.9; B, 10.5 +/- 0.4; and C, 11.0 +/- 0.8 hours. Diet had minimal influence on the half time of gastric emptying (diet A, 2.2 +/- 0.3; B, 2.6 +/- 0.4; and C, 2.9 +/- 0.3 hours; P greater than 0.05). The data indicate that gastric motility and emptying in healthy large-breed dogs were not affected by dietary composition. Because most large dogs are fed cereal-based food for reasons of cost and ease of use, these diets may have been wrongly incriminated as a predisposing factor in gastric dilatation-volvulus.     

Ultrasonographic assessment of the rate of solid-phase gastric emptying in dogs

Twelve healthy dogs were used in an ultrasonographic assessment of the effect of the composition of a solid meal on the rate of gastric emptying. The dogs were fasted for nine hours before they were fed either a standard or a high energy density test meal, in a cross-over study design. The gastric antrum was visualised with a 6.5 MHz microconvex transducer, and the area inside the elliptical shape defined by the craniocaudal and ventrodorsal diameters of the stomach was measured. Antral images were acquired at regular intervals for six hours after the ingestion of the test meal. Three indices to describe the rate of gastric emptying were computed: the gastric half-emptying time (t1/2), the time to 50 per cent maximal antral area (t50%), and the time of maximal antral area (tmax). The values of t50% and t1/2 calculated for the high energy density meals were significantly longer than for the standard meals, but there was no significant difference between the tmax values.     

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.     

Gastric emptying of liquids in the dog: effect of volume

Effect of liquid test meal volume on gastric emptying was investigated in healthy nonoperated dogs fed meal sizes of 6.6 to 110 ml/kg of body weight. For meals less than or equal to 66 ml/kg, the amount of test meal emptied from the stomach in 30 minutes vs meal size could be described as following a linear, exponential, or square root pattern. Deviation from these patterns was seen with test meals of 77, 88, and 110 ml/kg. A mean +/- SEM maximum of 0.99 +/- 0.06 ml/kg/min of liquid test meal was emptied from the stomach of dogs fed test meals of 77, 88, and 110 ml/kg. Massive gastric distension induced in dogs during this study did not alter gastric emptying of the liquid test meal.     

Retention of acetaminophen in an in vitro model of solid-phase gastric emptying of animals

OBJECTIVE: To apply an in vitro model for assessment of the solid-phase binding capacity of acetaminophen and thus assess the reliability of this marker for evaluation of solid-phase gastric emptying in vivo in animals. SAMPLE POPULATION: 4 test meals. PROCEDURES: A spectrophotometric method for detection of acetaminophen was validated and applied for assessment of the percentage retention of acetaminophen in the solid phase of 4 test meals. The gastric milieu was simulated by incubating each meal in artificial gastric juice for 2 hours in a shaking water bath maintained at 37 degrees C. Solid-phase retention was then assessed 3 times by measuring the amount of acetaminophen that had leached into the liquid phase. RESULTS: Acetaminophen was poorly retained in the solid phase of all the test meals examined in the study. There was also a large degree of variability in the percentage retention for each meal when the experiment was repeated 3 times. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of the results of this in vitro study confirmed that acetaminophen may not be an appropriate marker of solid-phase gastric emptying. The acetaminophen gastric emptying test should be applied only for the assessment of liquid-phase emptying in animals.     

Assessment of the rate of solid-phase gastric emptying in ponies by means of the 13C-octanoic acid breath test: a preliminary study

The aim of this study was to assess the feasibility of applying the 13C-octanoic acid breath test for assessment of gastric emptying in ponies by investigating the pattern of 13C enrichment in breath following the administration of a test meal +/- 13C-octanoic acid. After a 14 h fast, the ponies received either no meal (Test I) or a standardised test meal labelled with 0 mg (Test II), 125 mg (Test III), 250 mg (Test IV) or 500 mg (Test V) 13C-octanoic acid. For each test (I-V), exhaled breath samples were collected in duplicate at 1 h and immediately before ingestion of the test meal and at frequent intervals thereafter for 12 h. Breath samples were analysed by continuous flow isotope ratio mass spectrometry. Three indices of breath 13C-enrichment were computed; half dose recovery time (t1/2), gastric emptying coefficient (GEC) and time to peak breath 13C-enrichment t(max). For Tests I and II, the ratio of 13CO2:12CO2 remained stable for the duration of the sampling period. For Tests III, IV and V, an increase in the ratio of 13CO2:12CO2 was detected. The test was reproducible within individuals, and intersubject variation was low. Further validation studies of this noninvasive technique are justified.     

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.     

GASTRIC EMPTYING IN THE NORMAL DOG A Contrast Radiographic Technique

A total of 22 radiographic studies was made to determine comparative gastric emptying times of two different solid test meals (intact kibble food and ground kibble food mixed with barium sulfate suspension) in four mature (15-26 months) normal Beagle dogs under controlled conditions. Complete gastric emptying times of the intact kibble and ground kibble meals of a given dose (8 g/kg of dog food plus 5-7 ml/kg of the contrast agent) ranged from five to ten hours (7.6 ± 1.98 hours with intact kibble meal and 7.0 ± 1.86 hours with ground kibble meal). Feeding a halfdose of ground kibble meal (4 g/kg of dog food plus 3.5 ml/kg of the contrast agent) resulted in complete gastric emptying times of four to six hours (4.7 ± 0.67 hours). Individual dogs had repeatable gastric emptying times although the times varied among different dogs.     

Validation of the 13C-octanoic acid breath test for measurement of equine gastric emptying rate of solids using radioscintigraphy

REASONS FOR PERFORMING STUDY: Disordered gastric motility may be a significant factor in the pathogenesis of many equine conditions. Although tests for liquid phase emptying rate have been validated in the horse, there are no effective tests for solid phase emptying measurement that can be performed routinely in the field. OBJECTIVES: The objective of this study was the assessment of a novel stable isotope technique, the 13C-octane acid breath test (13C-OABT), for the measurement of gastric emptying of solid ingesta, by direct comparison with the optimum method of gastric scintigraphy. METHODS: To facilitate dual measurement of gastric emptying, a test meal was used containing baked egg yolk labelled with both 13C-octanoic acid and 99mtechnetium sulphur colloid. Simultaneous, serial lateral gastric scintigraphs and expiratory breath samples were obtained in 12 healthy horses after voluntary ingestion of the test meal. Analysis of breath 13CO2:12CO2 ratio was performed by continuous flow isotope ratio mass spectrometry. Power regression was used to determine the gastric emptying coefficient, the gastric half-emptying time (t 1/2) and duration of the lag phase (tlag). RESULTS: Significant correlations (P < 0.001) were found between the 2 techniques for measurement of both t 1/2 and tlag. In addition, scintigraphic left t 1/2 was correlated significantly to breath test gastric emptying coefficient (P < 0.001). CONCLUSIONS: It was concluded that the 13C-octanoic acid breath test is a reliable diagnostic procedure to measure gastric emptying rate of solids in the horse. POTENTIAL RELEVANCE: Being safe, noninvasive and easy to perform, this test has potential value as both sensitive diagnostic modality and humane research tool for motility studies.     

Gastric emptying as assessed by barium-impregnated polyethylene spheres in healthy dogs consuming a commercial kibble ration

Barium-impregnated polyethylene spheres (BIPS) were used to assess gastric emptying in medium-sized dogs consuming a commercial kibble ration. Two sizes of spheres were used: 1.5 mm and 5.0 mm in diameter. Ventrodorsal and right lateral recumbent radiographs were taken immediately before and after consumption of the test meal, and then hourly. The lag phase and the time to 25% (GET25), 50% (GET50), and 75% (GET75) gastric emptying of each sized marker were calculated. There was no significant difference between the lag phases of the small and large BIPS. There was a significant difference between the 1.5 and 5.0 markers at GET25, GET50, and GET75 in these medium-sized dogs. In a majority (70%) of the dogs in this study, GET25 of the 1.5-mm marker occurred at 4.73+/-1.44 hours; GET50 (1.5 mm) occurred at 8.29+/-1.62 hours, and GET75 (1.5 mm) occurred at 10.82+/-1.35 hours. The 5.0-mm markers tended to empty erratically and slowly. Four of the eight dogs retained some of the large markers in their stomachs at the end of the study period (24 hours).     

Use of 13C-acetate breath test for assessment of gastric emptying in horses

This study aimed to establish and standardize a breath test that uses 13C-acetate in a liquid diet for evaluation of gastric emptying in horses. Seven adult healthy thoroughbreds were used in this study. They were given 13C-acetate (125 mg, 250 mg, or 500 mg) in a test meal (2000 ml liquid diet) via an intranasal catheter. 13C concentrations in the exhaled CO2 were measured in samples taken before and after test meal administration using an infrared absorption spectroscope. In the 500 mg 13C-acetate group, Delta13CO2 showed a steep gradient immediately after meal administration compared to the 125 mg and 250 mg groups. Therefore, t(max) in the 500 mg group was easier to determine than in the 125 mg and 250 mg groups. In the 500 mg group, GEC, half-empty time (t1/2), calculated t(max) (t(lag)), and t(max) were 1.95 +/- 0.28 (mean +/- SD), 229.2 +/- 57.0 (min), 139.2 +/- 22.2 (min), and 124.0 +/- 28.4, respectively. Differences in CV observed in the 500 mg group were lower than those in the 125 mg and 250 mg groups. This study demonstrates that the 13C-acetate breath test is useful for evaluating gastric emptying in horses since it is non-invasive and does not require set up of special facilities or equipment. Optimum evaluation of gastric emptying in horses can be achieved with 500 mg of 13C-acetate given in a liquid diet.     

SCINTIGRAPHIC EVALUATION OF SOLID-PHASE GASTRIC EMPTYING IN THE DOG

A technique for scintigraphically quantitating solid-phase gastric emptying in the dog was developed in a Beagle model. The test meal was determined to empty in a linear fashion, indicating a solid-phase label. The evaluation was performed on a group of dogs presented for gastrointestinal signs that were judged to have normal liquid barium sulfate fluoroscopic and radiographic studies. The results of this study indicate that this technique is valuable for identifying those patients with surgically correctable pyloric obstruction that exhibit normal gastric emptying of liquid barium.     

Role of cholecystokinin in the gastric motor response to a meal in horses

OBJECTIVE: To measure plasma cholecystokinin (CCK) activity and the effect of a CCK-1 receptor antagonist on accommodation of the proximal portion of the stomach, and subsequent gastric emptying, in horses after ingestion of high-fat or high-carbohydrate meals. ANIMALS: 6 healthy adult horses with gastric cannulas. PROCEDURES: In the first study, horses were offered a high-fat (8% fat) or a high-carbohydrate (3% fat) pelleted meal of identical volume, caloric density, and protein content. Related plasma CCK-like activity was measured by radioimmunoassay (RIA). In a separate experiment, a horse was fed a grain meal with corn oil and phenylalanine, and plasma CCK activity was assessed by bioassay. A second study evaluated the effect of a CCK-1 receptor antagonist, devazepide (0.1 mg/kg, IV), on gastric accommodation and emptying following a meal of grain supplemented with either corn oil (12.3% fat) or an isocaloric amount of glucose (2.9% fat). Gastric tone was measured by a barostat and emptying by the (13)C-octanoic acid breath test. RESULTS: No plasma CCK-like activity was detected by RIA or bioassay before or after ingestion of meals. Preprandial devazepide did not alter the gastric accommodation response but did significantly shorten the gastric half-emptying time and time to peak breath (13)CO(2) content with the glucose-enriched meal. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, CCK participates in regulating the gastric motor response to a meal. Compared with other species, horses may be more responsive to carbohydrate than fat. A vagovagal reflex most likely mediates this regulation, with CCK as a paracrine intermediary at the intestinal level.     

Gastric emptying of glucose in the dog

The 30-minute gastric emptying of test meals consisting of 2.5%, 4%, 7%, 15%, or 25% glucose was evaluated in healthy, nonoperated dogs, using an orogastric intubation technique. An inversely proportional exponential relationship was found between test meal glucose concentration and amount of test meal emptied from the stomach in 30 minutes. For the 7%, 15%, and 25% glucose test meals, a mean (+/- SEM) of 1.11 +/- 0.03 kcal/min emptied into the duodenum, which represented 0.054 +/- 0.004 kcal/min/kg of body weight. Test meals of 2.5% and 4% glucose supplied significantly fewer kcal per minute to the duodenum than did the other 3 meals, indicating that control of gastric emptying of hypotonic glucose meals may be different than that of isotonic or hypertonic test meals in the dog.     

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

Total gastric emptying time was determined in nine mongrel dogs using a barium meal contrast procedure. Within the group, total gastric emptying time ranged from 7.0–15.0 hours. Comparison of the population mean showed a statistical difference (p − 0.01) from previously published values. Individual dogs showed consistent total gastric emptying time over three trials. The technique can be used to test the effect of a procedure on total gastric emptying time when a normal value has been established for the dog. Due to the wide range of normal values observed, evaluation of clinical patients could be difficult unless there is a gross abnormality in function.     

Gastric emptying of a radionuclide-labeled test meal after surgical correction of gastric dilatation-volvulus in dogs

Gastric emptying of a radionuclide-labeled test meal was studied in 10 dogs that had been treated surgically for gastric dilatation-volvulus and in 10 clinically normal (control) dogs. There were no significant differences between the gastric emptying rates and patterns in treated and in control dogs. Thus, there are no indications that gastric emptying is delayed in dogs that have recovered from gastric dilatation-volvulus, and there is no reason for pyloric surgery in dogs with this condition.