gastric_emptying_BIPS

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). J Am Anim Hosp Assoc 2001;37:444–452.

O. Lynne Nelson, DVM, MS, Diplomate ACVIM (Internal Medicine, Cardiology) Albert E. Jergens, DVM, MS, Diplomate ACVIM Kristina G. Miles, DVM, MS, Diplomate ACVR William F. Christensen, PhD

O From the Departments of Veterinary Clinical Sciences (Nelson, Jergens) and Veterinary Radiology (Miles), College of Veterinary Medicine, and the Department of Statistics (Christensen), Iowa State University, Ames, Iowa 50011.

Address all correspondence and reprint requests to Dr. Nelson, Veterinary Teaching Hospital, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164-7010.

This work was supported by a Research Initiation Grant from Iowa State University.

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Introduction Gastric emptying disorders are common problems in veterinary practice.

Causes of delayed gastric emptying can be attributed to structural disease such as mass lesions, pyloric hypertrophy, gastric foreign bodies, or functional disease such as alternations in autonomic nervous system tone, visceral inflammation, metabolic disorders, and electrolyte abnormalities.1-3 Structural lesions of the stomach may be identified with barium sulphate suspension studies, but functional alterations may be missed with this commonly used technique. The current gold standard for diagnosing delayed gastric emptying of solids in humans is nuclear scintigraphy.4 Although scintigraphy is regarded as the technique of choice, it is usually only available through large referral institutions.

Other disadvantages of this method include the cost of radionuclides, the specialized training required, and the hazards of handling these materials. Unfortunately, there is no readily available method to quantitate the gastric emptying of solid particles in clinical veterinary practice.

Recently, radiopaque markers have been used to assess gastric motor function in humans, dogs, and cats.5-9 Early studies in humans indicated that passage of the markers correlated well with passage of a test meal.10 The emptying of the markers was altered with the density and nutritive content of the test meal.10 Other investigations have found that the markers parallel scintigraphic quantitation of the emptying of solids from the stomach.11 Recent studies in dogs have revealed that radiopaque markers leave the stomach at a rate proportional to that of the disappearance of food (dry matter).12 Radiographic studies utilizing these markers are simple to perform, and the cost of the markers is nominal. Preliminary reports in dogs suggest that radiopaque markers may be a useful means to assess gastric emptying of solids in a clinical setting.13,14 JOURNAL of the American Animal Hospital Association

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The purpose of this study was to develop a standardized radiographic method, using barium-impregnated polyethylene spheres (BIPS), for assessing gastric emptying in medium-sized dogs that were fed a standard kibble diet. In the authors’ practice, owners report feeding dry commercial dog foods most commonly. Since the primary influence on the rate of gastric emptying is determined by the formulation and nutritive content of the diet, gastric emptying data that is generated by using one dietary formulation cannot be extrapolated to others.15,16 In addition, the size of the meal and the patient body size are thought to be equally important factors in governing the rate of gastric emptying of solid particles.9,15,16 The authors hypothesized that the 1.5mm diameter marker would pass from the stomach proportional to the rate of solid food in medium-sized dogs, while the 5.0-mm marker would not pass until the onset of the migrating motor complex (MMC) to clear indigestible particles. The authors also suspected that the gastric emptying times for kibble may be different than those reported for canned diets, which may vary considerably in caloric density. The rates of gastric emptying of two sizes of BIPS were determined in medium-sized dogs using a commonly fed kibble ration.

radiographs were obtained immediately before and after feeding of the test meal. Radiographs were then taken hourly until 90% of the total marker number had emptied from the stomach or until 12 hours had lapsed, whichever occurred first. Ventrodorsal and right lateral radiographs were again obtained at 24 hours postconsumption of the test meal to assess if all markers had passed from the stomach.

Gastric emptying was interpreted from the radiographs by allocation of BIPS into two categories: marker in the stomach (MI) or marker out of the stomach (MO). On the uncommon occasion that a marker’s location could not be definitively determined, it was counted as MI. The small markers were allocated separately from the large markers into the categories (MO or MI) during the same test period.

The percentage of each sized marker that had emptied from the stomach was calculated using the formula: MO/(MO+MI) × 100. The calculations of 25% (GET25), 50% (GET50), and 75% (GET75) gastric emptying times were determined for each sized marker. The lag phase of gastric emptying, defined as the initial period during which <5% of the markers left the stomach (GET5), was calculated for each sized marker.

Materials and Methods

Because the evaluation of the percentage of gastric emptying on each subject took place at specific times (i.e., hours 1, 2,…12, and 24), the authors note that their data does not give a precise measure of the time to gastric emptying (GET). For example, if case no. 1 achieved 69% gastric emptying for the 5-mm marker at hour 6 and 75% gastric emptying (GET75) at hour 7, GET75 actually occurred sometime between hour 6 and 7, but hour 7 is recorded as GET75. This type of data is called interval-censored data.

In order to carry out the best possible analysis of such data, the authors utilized methodology for interval-censored data analysis, common in survival analysis and lifetime data. For such data, the authors fit the time-to-GET data to a “failuretime distribution” and then used this distribution to estimate quantiles of interest via the statistical tool of maximum likelihood.

The data’s fit to several commonly used failure-time distributions (e.g., lognormal, Weibull, exponential, and loglogistic) was evaluated. It was determined that for all eight sets of data, including combinations of the four gastric emptying events (GET5, GET25, GET50, and GET75) and the two markers (1.5 mm and 5 mm), the lognormal distribution fit adequately. It was recognized, however, that some of the data is right-censored (e.g., the measurements of GET75 using the 5-mm marker) and that other distributions also fit the data adequately. The authors then evaluated the effect of the marker by using the Lifereg procedure in a statistical analysis software packagee in order to fit the model GET = INTERCEPT + DOG EFFECT + MARKER EFFECT + ERROR by maximum likelihood, where ERROR is lognormally distributed. Next, maximum likelihood estimates of the lognormal distribution parameters were obtained for each of the eight data sets. These estimates were used to

Eight young adult, mixed-breed dogs (four male, four female) were used in this study. The weights ranged from 9.5 to 13.6 kg. Each dog had a standard physical examination that was within normal limits. None of the dogs exhibited signs of gastrointestinal disease. All dogs received routine vaccinations and were dewormed for gastrointestinal parasites with a road spectrum anthelmintic.a The dogs were housed in the Laboratory Animal Resources Center at Iowa State University and were cared for according to the National Institute of Health Guide for the Care and Use of Laboratory Animals. Prior to the study period, the dogs were fed a maintenance rationb and given ad-libitum access to water.

Food was withheld for 24 hours prior to the radiographic study, but access to water was provided. Barium-impregnated polyethylene radiopaque spheresc having 1.5-mm and 5.0-mm outside diameters were mixed with a test meal. The markers had a smooth surface and a density of 1.37 g/mL. The test meal consisted of a commercially prepared maintenance kibble rationb mixed with 30 1.5-mm and 10 5.0-mm diameter BIPS. The caloric density of the test meal was 3,702 kcal/kg. The amount of kibble fed as the test meal was calculated using the formula: 0.5 maintenance energy requirements (MER) [0.5 × 2 (30 wt kg + 70)]. Marker adherence to the test meal was assured by mixing the BIPS with 1.25 ounces of chicken baby food.d The dogs were positioned in a standard manner for the radiographic procedures. Although stress has not been shown to be a significant factor in a previous BIPS study,8 all dogs were “acclimated” to the radiographic procedure by an earlier pilot study using the same radiographic technique. Ventrodorsal and right lateral recumbent abdominal

Statistical Analysis

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construct estimated time-to-GET distribution plots. Numerical summaries of important quantiles, their standard errors, and 95% confidence intervals were calculated. A P value of <0.05 was considered significant.

Results There were significant differences between the gastric emptying of the two markers at GET25 (P=0.0013), GET50 (P=0.0217), and GET75 (P=0.0247). There was no significant difference between the two markers for GET5 (P=0.1362).

The dog effect was significant in the model for each of the four gastric emptying events, indicating dog to dog variability.

Numerical summaries of important quantiles, their standard errors, and 95% confidence intervals are given in Tables 1 through 8. These tables indicate GET in hours based on the proportion of dogs that achieved the result. For each gastric emptying event (GET5, GET25, GET50, and GET75) and for both BIPS sizes, the authors estimated the time at which the event occurred from 0.10 to 0.90 quantiles of the study population. For purposes of discussion and subjective clinical relevance, the authors chose 0.70 to represent the “majority” of the study data points. However, Tables 1 through 8 allow the clinician to evaluate the marker size and the gastric emptying time compared to the quantile of particular personal interest/relevance.

In this study, one of the eight dogs did not achieve GET25 of the 5-mm marker within 24 hours (end of data collection period). Three dogs did not achieve GET50, and four dogs did not achieve GET75 of the 5-mm marker within 24 hours. Because of the abundance of right-censoring in the data for the 5-mm markers, the authors can only recommend use of the quantiles in the following ranges: 5mm markers/GET25, 0.10 to 0.80; 5-mm markers/GET50 and GET75, 0.10 to 0.50.

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Discussion The purpose of this study was to develop a standardized radiographic method using BIPS for assessing gastric emptying in medium-sized dogs fed a standard kibble diet. A common commercial dry kibble dog food was used for this study for two reasons. First, the majority of the authors’ canine patients being evaluated for gastric motility disorders are fed dry dog foods and are accustomed to these preparations. In addition, the time required for kibble to be processed and emptied from the stomach may be different than canned food, which contains a significant portion of liquid. Therefore, to completely assess a patient’s potential gastric motility disturbance, utilization of the data gathered from the actual consumed ration compared to known normal rates of gastric emptying with the same product would likely yield more valuable information. Secondly, most reputable commercial dry dog foods are relatively consistent in caloric density compared to canned diets, which can vary in water and caloric content;17 thus, use of a particular dry food may be found to be a less significant variable. The authors chose to feed 0.5 MER per test meal to their subjects to mimic a typical twice-daily feeding regimen.

The number and the size of the BIPS were administered according to manufacturer’s recommendations. The markers (10 5.0 mm, 30 1.5 mm) were easy to identify and count on the two radiographic views. Occasionally, markers in the transverse colon (ventrodorsal view) and the proximal duodenum (lateral view) overlaid the gastric silhouette, making it difficult to determine if a marker was actually within the stomach. These “problem areas” have been previously described.8 Difficulty in locating a marker was relatively uncommon in this study. Evaluation of radiographs taken 1 hour later usually revealed the marker’s true location. When

Table 1 A Numerical Summary of the Time to GET5* for the 1.5-mm BIPS,† Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET5 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

0.43 0.65 0.89 1.15 1.47 1.88 2.44 3.32 5.08

0.28 0.35 0.41 0.48 0.56 0.69 0.90 1.34 2.47

0.12 0.23 0.36 0.51 0.69 0.92 1.18 1.50 1.96

1.53 1.86 2.19 2.59 3.10 3.84 5.04 7.31 13.16

* GET5=the time at which 5% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres

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Table 2 A Numerical Summary of the Time to GET25* for the 1.5-mm BIPS,† Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET25 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

1.10 1.57 2.03 2.52 3.10 3.80 4.73 6.11 8.71

0.47 0.57 0.65 0.76 0.90 1.11 1.45 2.05 3.43

0.48 0.78 1.08 1.40 1.75 2.14 2.60 3.17 4.02

2.54 3.18 3.82 4.55 5.48 6.74 8.61 11.78 18.87

* GET25=the time at which 25% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres

Table 3 A Numerical Summary of the Time to GET50* for the 1.5-mm BIPS,† Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET50 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

3.34 4.17 4.89 5.60 6.36 7.23 8.29 9.72 12.13

0.83 0.88 0.94 1.03 1.15 1.33 1.62 2.09 3.07

2.05 2.75 3.35 3.91 4.47 5.04 5.65 6.37 7.39

5.43 6.31 7.13 8.02 9.06 10.38 12.15 14.83 19.91

* GET50=the time at which 50% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres

a marker’s location was in question in this study, it was arbitrarily counted as being within the stomach.

A lag phase of approximately 2.5 to 3.5 hours occurred before the BIPS began to consistently leave the stomach in the majority (70%) of the study subjects. GET5 for the 1.5mm and 5.0-mm markers was 2.44±0.90 hours and 3.44±0.99 hours, respectively. The lag phase was defined as the period during which <5% of the markers had left the stomach.8 The lag phase of gastric emptying represents the

time it takes for solid food to be triturated to particle sizes small enough (<1 to 2 mm) to begin passing from the stomach at a uniform rate.4 This finding was similar to lag phases reported in other investigations using BIPS in dogs fed canned rations.8 Humans with secondary gastric motility disorders, such as diabetes mellitus, often have a prolongation of this phase of gastric emptying. Dyspepsia, nausea, and anorexia are often attributed to this abnormality.

Prokinetic drug therapy is often effective for hastening all

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phases of gastric emptying, including lag phases.4,18 Determination of lag phases would appear to have pertinent clinical and therapeutic applications. It is not known whether dogs suffer from pathological conditions that may prolong this period.

There was no significant difference between the mean lag periods of the large and small markers in the study reported here. The authors hypothesized that the large markers would be treated as indigestible solids and emp-

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tied much later than the small markers in this study. The lack of difference between the emptying of the large and small markers at GET5 is likely due to the large standard error at this time and the small number of large BIPS used (10 5.0-mm spheres). Also, the overall erratic emptying of the 5.0-mm markers may have contributed to this observation. It is also possible that the 5.0-mm markers did not behave as indigestible particles and emptied as solid food.

This explanation is thought to be less likely since the large

Table 4 A Numerical Summary of the Time to GET75* for the 1.5-mm BIPS,† Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET75 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

6.32 7.20 7.92 8.58 9.26 9.98 10.82 11.89 13.56

0.94 0.90 0.90 0.94 1.01 1.15 1.35 1.68 2.30

4.73 5.64 6.34 6.93 7.47 7.97 8.47 9.02 9.73

8.45 9.20 9.90 10.63 11.47 12.50 13.82 15.67 18.89

* GET75=the time at which 75% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres

Table 5 A Numerical Summary of the Time to GET5* for the 5.0-mm BIPS,† Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET5 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

0.88 1.22 1.55 1.91 2.31 2.80 3.44 4.37 6.10

0.36 0.42 0.48 0.55 0.64 0.77 0.99 1.38 2.25

0.40 0.62 0.85 1.09 1.35 1.63 1.96 2.36 2.96

1.94 2.40 2.84 3.35 3.98 4.82 6.05 8.11 12.59

* GET5=the time at which 5% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres

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Table 6 A Numerical Summary of the Time to GET25* for the 5.0-mm BIPS† Relative to Percentile, Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET25 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

1.63 2.62 3.69 4.94 6.49 8.53 11.43 16.09 25.86

0.87 1.18 1.51 1.94 2.53 3.43 4.93 7.74 14.74

0.58 1.08 1.65 2.29 3.03 3.88 4.91 6.27 8.46

4.62 6.34 8.24 10.65 13.93 18.78 26.61 41.30 79.34

* GET25=the time at which 25% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres Note: Because of the abundance of right-censoring in the data for the 5-mm markers, the authors can only recommend the use of the quantiles from the range of 0.10 to 0.80.

Table 7 A Numerical Summary of the Time to GET50* for the 5.0-mm BIPS† Relative to Percentile, Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET50 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

2.82 4.98 7.51 10.67 14.81 20.57 29.21 44.06 77.88

1.83 2.68 3.72 5.21 7.54 11.38 18.13 31.62 68.03

0.79 1.73 2.85 4.10 5.46 6.95 8.66 10.79 14.06

10.04 14.32 19.81 27.78 40.19 60.83 98.58 179.87 431.49

* GET50=the time at which 50% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres Note: Because of the abundance of right-censoring in the data for the 5-mm markers, the authors can only recommend the use of the quantiles from the range of 0.10 to 0.50.

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marker emptying differed significantly from the small marker emptying at GET25, GET50, and GET 75.

In contrast to previous reports in the dog, the authors found that the 1.5-mm and the 5.0-mm BIPS emptied at different rates as evidenced by GET25, GET50, and GET75.8 The small markers appeared to empty quickly and consistently after the initial lag phase, consistent with the steady state of gastric emptying of solid particles. The larger markers, however, emptied more slowly and erratically. The GET25 of small markers in the majority (70%) of the subjects was 4.73±1.44 hours, while the GET50 and GET75 were 8.29±1.62 hours and 10.82±1.35 hours, respectively.

These times were similar to previous reports of 4.85±2.15 hours (GET25), 6.05±2.99 hours (GET50), and 8.32±2.72 hours (GET75), utilizing similar clinical techniques.8 The authors felt the smaller markers were emptying as solid particles based on the characteristic consistent rate of marker disappearance and the similar results that were obtained when making comparisons to other investigations.8 Also, recent evidence suggests that the rate of emptying of the small markers correlates well with the rate of emptying of dry matter from the stomach.12 The differences between the GETs of these two studies could be related to variation in the quantity and caloric density of the test meal, as well as differences in patient sizes or individual animal variation.

The 5.0-mm BIPS emptied from the stomach in a slower, more erratic manner than the 1.5-mm BIPS. In this study, four of the eight dogs did not achieve GET75 of the 5.0mm markers by 24 hours. This observation could be in support of the authors’ hypothesis that the larger markers would be handled as indigestible particles and eliminated

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by the MMC. Groups of the larger markers tended to shift into the pyloric antral area and be retained in that location before being expelled from the stomach as a bolus (Figures 1, 2). This “pyloric sifting” of large markers was thought to represent movement of particles into the antrum so that peristaltic contractions could mix and triturate the particles until they were broken down (as digestible particles) or swept into the duodenum by a MMC (as indigestible particles). The underlying cause for the difference in emptying of the large BIPS over the previously reported study is undetermined.8 It is possible that the size of the subjects in this study (average 11.8 kg compared to 20.6 kg8) was a factor in retention of the larger markers, if the size of particle treated as indigestible is dependent upon the size of the patient. The differences in the quantity (0.50 MER versus 0.25 MER8) and type of test meal (kibble versus canned8) may have caused the larger markers to be handled differently. Because of the unpredictable behavior of the large markers and the abundance of right-censoring, the clinical information when utilizing the 5.0-mm markers should be interpreted cautiously. Further investigation on the use of BIPS in a larger number of small canine patients is warranted.

The small number of dogs and the lack of comparison to a standard measure of gastric emptying, such as nuclear scintigraphy, are potential limitations to this study. A recent preliminary investigation yielded controversial information regarding gastric emptying of BIPS.19 The authors did feel, however, it was likely that the smaller BIPS were emptying from the stomach proportional to food, based on the characteristic consistent rate of marker

Table 8 A Numerical Summary of the Time to GET75* for the 5.0-mm BIPS† Relative to Percentile, Standard Errors, and 95% Confidence Intervals Proportion of Dogs

Time to GET75 (hrs)

Standard Error±

Lower Confidence Interval

Upper Confidence Interval

0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90

4.27 7.40 11.02 15.47 21.25 29.18 40.98 60.97 105.79

2.71 3.86 5.38 7.75 11.57 17.78 28.85 50.43 107.40

1.23 2.67 4.23 5.80 7.31 8.79 10.31 12.05 14.46

14.79 20.55 28.68 41.29 61.79 96.94 162.84 308.43 773.78

* GET75=the time at which 75% of the marker/test meal combination has passed from the stomach † BIPS=barium-impregnated polyethylene spheres Note: Because of the abundance of right-censoring in the data for the 5-mm markers, the authors can only recommend the use of the quantiles from the range of 0.10 to 0.50.

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1A

Figures 1A, 1B—Ventrodorsal (1A) and right lateral (1B) radiographs of case no. 4 of the study, 9 hours postingestion of the test meal with barium-impregnated polyethylene spheres (BIPS). Note that all of the 1.5-mm markers have left the stomach, but all of the 5.0-mm markers are retained and appear to have “sifted” into the pyloric region.

1B

disappearance preceded by a lag period. In addition, the authors felt the smaller markers could be emptying as solid particles based on the similar results of gastric emptying that were obtained when comparisons were made to other investigations.8 The larger markers’ unpredictable disappearance from the stomach may have been influenced by the quantity

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2A

Figures 2A, 2B—Ventrodorsal (2A) and right lateral (2B) radiographs of case no. 4 of the study, 10 hours postingestion of the test meal with BIPS. Note that five of the 10 5.0mm markers have been expelled from the stomach within the past hour. The remaining five markers are still located in the pyloric antral area.

2B

and density of the test meal, or the markers may have been treated as indigestible particles in these medium-sized dogs.

The usefulness in evaluating the passage of the large BIPS has yet to be determined. A potential situation where large markers may be of value is in the assessment of obstructive lesions, such as pyloric hypertrophy.

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Conclusion The authors have described the use of BIPS to assess gastric emptying in healthy, medium-sized dogs that have been fed a maintenance kibble ration. The authors felt that the information gathered using the small (1.5 mm) markers was most useful. The authors found the technique to be simple to perform, and the cost of the markers is nominal. Further investigation into the value of utilizing this technique in clinical patients is warranted. a Panacur (Fenbendazole); Hoechst Roussel Vet, San Antonio, TX b Canine Maintenance dry ration; Hill’s Pet Nutrition, Inc., Topeka, KS c Barium-impregnated polyethylene spheres; Chemstock Animal Health Ltd, Christchurch, New Zealand d Chicken baby food; Gerber Products Company, Fremont, MI e SAS statistical software; Cary, NC

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12. Hall JA, Twedt DC, Burrows CF. Gastric motility in dogs. Part 2. Disorders of gastric motility. Comp Cont Ed 1989;11:1373-1390.

13. Guilford WG, Strombeck DR. Chronic gastric diseases. In: Guilford WG, ed. Strombeck’s small animal gastroenterology. 3rd ed. Philadelphia: WB Saunders, 1996:275-302.

14. Maurer AH. Scintigraphic evaluation. In: Gore RM, ed. Textbook of gastrointestinal radiology. Philadelphia: WB Saunders, 1994:316-332.

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Gastroenterol 1984;87:895-902.

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September/October 2001, Vol. 37 18. Allan FJ, Guliford WG, Robertson ID, Jones BR. Gastric emptying of solid radiopaque markers in healthy dogs. Vet Radiol & Ultrasound 1996;37:336-344.

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11. Vantrappen G. Methods to study gastric emptying. Dig Dis Sci 1994;39:91S-94S. 12. Guilford WG, Lawoko CRO, Allan FJ. Accuracy of localizing radiopaque markers by abdominal radiography and correlation between their gastric emptying rate and that of a canned food in dogs.

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15. Guilford WG, Strombeck DR. Gastric structure and function. In: Guilford WG, ed. Strombeck’s small animal gastroenterology. 3rd ed.

Philadelphia: WB Saunders, 1996:239-255.

16. Minami H, McCallum RW. The physiology and pathophysiology of gastric emptying in humans. Gastroenterol 1984;86:1592-1610.

17. Hornoff WJ, Koblik PD, Strombeck DR, Morgan JP, Hansen G. Scintigraphic evaluation of solid-phase gastric emptying in the dog.

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18. Caballero-Plasencia AM, Muros-Navarro MC, Martin-Ruiz JL, et al.

Gastroparesis of digestible and indigestible solids in patients with insulin-dependent diabetes mellitus or functional dyspepsia. Dig Dis Sci 1994;39:1409-1415.

19. Lester NV, Roberts GD, Newell SM, et al. Assessment of bariumimpregnated spheres (BIPS) as a measure of solid phase emptying in normal dogs—comparison to scintigraphy. Proceedings of the American College of Veterinary Radiology, Chicago, IL, December 1997.

Vet Radiol Ultrasound 1998;39:262.