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Keywords:

  • motility;
  • post-operative ileus;
  • smartpill;
  • stomach;
  • transit time

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Objective

To determine if general anesthesia with sevoflurane and laparoscopic surgery changed gastric and small bowel propulsive motility or pH in dogs.

Study design

Prospective, controlled trial.

Animals

Twelve, 19–24 months old, female, Treeing Walker Hound dogs, weighing 23–30 kg.

Methods

Dogs were anesthetized for a median of 8.5 hours during another study to determine the minimum alveolar concentration of sevoflurane using a visceral stimulus. Gastric and small bowel motility were determined using a sensor capsule that measures pressure, pH and temperature. Gastric transit time and motility index were calculated. For 8/12 dogs, gastric motility, pH and transit time were measured. In 4/12 dogs, small bowel motility and pH were measured.

Results

Anesthesia decreased gastric and small bowel motility but did not change luminal pH. Mean gastric contraction force decreased from median (range) 11 (8–20) to 3 (1–10) mmHg (< 0.01) and gastric motility index decreased from 0.63 (0–1.58) to 0 (0–0.31; = 0.01). Frequency of contractions did not change, 3.7 (1.6–4.4) versus 2.8 (0.1–5.1) contractions minute−1 (= 0.1). Gastric motility returned to normal 12–15 hours following anesthesia. Gastric emptying was prolonged from 12 (5.3–16) to 49 (9.75–56.25) hours (< 0.01). Mean small bowel contraction force decreased from 34 (24–37) to 3 (0.9–17) mmHg (< 0.02) and motility index decreased from 3.75 (1–4.56) to 0 (0–1.53; = 0.02). Frequency of contractions did not change, 0.5 (0.3–1.4) versus 1.4 (0.3–4.6) contractions minute−1 (= 0.11). Small bowel motility returned within 2 hours after anesthesia. Laparoscopy did not result in changes to gastric or small bowel parameters beyond those produced by general anesthesia.

Conclusions and clinical relevance

The force of gastric and small bowel contractions decreased during sevoflurane anesthesia for laparoscopy. Although gastric motility returned to normal within 12–15 hours the impairment of gastric emptying lasted 30–40 hours, predisposing dogs to postoperative ileus.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Postoperative gastrointestinal complications such as functional ileus, vomiting and constipation have been reported in humans, horses, rats, sheep and dogs (Tinckler 1965; Van der Gaag et al. 1981; Furuta et al. 2002; Behm & Stollman 2003; Trudel et al. 2003; Yanagida et al. 2004; Senior et al. 2006). In client owned dogs, the only report indicates that postoperative ileus (POI) occurred in 8% of 109 ovariohysterectomies evaluated. The dogs showed postoperative clinical signs and radiological features of ileus (Van der Gaag et al. 1981). An additional case report from a dog reports aerophagia with gastric dilation following anesthesia (Savas et al. 2001). It is the authors' experience that while post-operative gastrointestinal (GI) complications are infrequent, they appear to occur with some prevalence in geriatric or severely compromised dogs following abdominal surgery. Direct GI manipulation during surgery is considered one of the leading causes for post-operative GI dysfunction (Tinckler 1965; Graves et al. 1989; Behm & Stollman 2003; Yanagida et al. 2004; Senior et al. 2006). However, similar complications have been observed following anesthesia in the absence of abdominal surgery (Tinckler 1965; Little et al. 2001; Andersen et al. 2006; Senior et al. 2006; Maron & Fry 2008).

Studies in humans, horses and dogs have shown that general anesthesia alone can negatively impact GI motility and induce POI (Tinckler 1965; Schurizek et al. 1989; Lester et al. 1992; Durongphongtorn et al. 2006). The studies suggest that all of the inhaled and injectable anesthetics tested, except nitrous oxide, decreased GI motility (e.g. cyclopropane, ether, halothane, enflurane, isoflurane, xylazine, ketamine, diazepam, thiopental, guaifenesin, opioids). The anesthetics tested decreased the myolectrical activity amplitude and prevented the normal inter-digestive migratory motor complexes from occurring throughout the GI tract. The outcome parameters measured showed a delay in time to first flatus, time to first solid bowel movement, time to start eating and time to hospital discharge (Behm & Stollman 2003).

In the present study we investigated whether general anesthesia and laparoscopic surgery decreased GI activity or changed GI luminal pH in dogs. Propulsive motility was measured as it represents movement of luminal contents through the GI tract. For example, administration of opioid drugs increases GI myoelectrical activity but decreases GI propulsive motility, delays gastric emptying and induces small and large bowel stasis (Bardon & Ruckebusch 1985; Roger et al. 1994; Wood & Galligan 2004; Boscan et al. 2006).

To measure propulsive motility, a commercially available wireless motility capsule (WMC) was employed (SmartPill® Corporation, NY, USA). The WMC is a minimally-invasive sensor that simultaneously measures intraluminal pressure, pH and temperature. This technique has been validated for the study of GI propulsive activity and transit time in humans (Kuo et al. 2007; Sarosiek & Majewski 2007; Parkman 2009; Rao et al. 2009) and dogs (Boillat et al. 2010a,b).

Material and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Twelve healthy adult female Treeing Walker Hound dogs, median (range) 21 (19–24) months, old, weighing 27.2 kg, (23–30) kg with body condition scores of 5–6/9 (Toll et al. 2010) were utilized for the study. The dogs were anesthetized as part of a separate study to test the minimum alveolar concentration (MAC) of sevoflurane during ovarian ligament stimulation (Boscan et al. 2011a,b). The study was approved by the University animal care and use committee (protocol 10-1935A).

Fourteen days prior the study, the dogs were acclimated and housed in individual runs to accustom them to the environment. The environment consisted of 12 hours light/dark cycle, environmental enrichment and playing time with people and other dogs 2–4 times per day, the room temperatures ranged between 20–22 °C. The dogs were fed twice daily with dry Purina ENa according to their resting energy requirements (30 ×  BW (kg) + 70 kcalday−1; Toll et al. 2010). For the unanesthetized control data, on the study day, dogs were fasted overnight for 12 hours. In the morning, between 07:00–07:30 hours, the dogs were fed their respective calculated morning meal. Following their morning meal, the WMC was administered with 30 mL of water and thereafter the dogs were fed following their regular schedule. The dogs had water available at all times.

At least 7 days were allowed after the WMC exited the body before the dogs were anesthetized for the MAC determination and laparoscopic ovariectomy. The dogs were randomly assigned to either the gastric or the small bowel motility groups. For the dogs in the gastric motility group the WMC was administered between 07:00–07:30 hours on the same day as it was anesthetized. For the dogs in the small bowel motility group, the WMC was administered the day before anesthesia between 13:00 and 16:00 hours. For both groups, dogs were fasted for 12 hours before administration of the WMC. The WMC was administered with 30 mL of water immediately after their morning meal, mimicking the conditions used for the control study. After recovering from anesthesia, all dogs were fed twice a day starting on the evening after anesthesia and offered water ad libitum. When the WMC exited the body, it was the end of the study. The dogs were not fasted for anesthesia to avoid the potential effect of fasting on GI motility and because of the need to administer the WMC with food. Both groups ate their meal approximately 1 hour before induction of anesthesia.

The WMC is a 12 × 26 mm commercially available minimally-invasive, wireless, sensor that measures intraluminal pressure, pH and temperature. The data are collected and stored in a receiving device worn by the dog in a vest. At the end of the study, the data from the receiver were downloaded using the WMC provided software for analysis (MotiliGi version 2.5 from SmartPill Corporation, NY, USA). The analysis was performed manually to avoid computer-induced errors from default settings. The parameters recorded directly from the WMC were: pH, maximum & mean pressure of luminal contractions, frequency of contractions and temperature. The maximum and mean pressure parameters are indicators of the force of GI contractions. In addition, we calculated the motility index, transit time or emptying time. The motility index is the area under the pressure curve generated by all contractions over 10 mmHg, divided by time and provides a more detailed assessment of the luminal pressure. The gastric emptying time (GET) and small bowel transit time are the times required for the WMC to go through either the stomach or small bowel.

To determine the WMC location within the GI tract, we used the displayed pH values. As previously reported in dogs the WMC is considered to be in the stomach if the pH was <4 and high frequency contractions are observed (Boillat et al. 2010a,b). The WMC is in the small bowel lumen if the pH shows a consistent increase of three or more units from the gastric pH, indicating passage through the pylorus into the duodenum. The physiological small bowel pH is reported to be between 6 and 8 (Boillat et al. 2010a,b). When the WMC passes from the small bowel into the large bowel, the displayed pH decreases by 0.5–1 unit. In addition, the pressure contraction intensity decreases when compared to the small bowel. Large bowel data are not reported in this study because no dog was anesthetized with the WMC located in the large bowel. Previous studies in dogs and humans have shown the capability and repeatability of the WMC technology when measuring GI pressure, pH, temperature, GET and GI transit time (Kuo et al. 2007; Sarosiek & Majewski 2007; Parkman 2009; Rao et al. 2009; Boillat et al. 2010a,b).

All dogs were anesthetized between 08:30 and 08:45 hours using only sevoflurane in oxygen administered via a mask. No premedication or induction agents were used. After induction of anesthesia, the dogs were orotracheally intubated. Instrumentation and monitoring consisted of capnography, end-tidal sevoflurane concentration, ECG for heart rate and rhythm, esophageal temperature and an arterial catheter placed in the dorsal pedal artery to monitor blood pressure. Instrumentation took approximately 30–45 minutes. The end-tidal CO2 was maintained between 40–45 mmHg (5.3–6 kPa) in both groups by using positive pressure ventilation during the anesthesia period. Mean arterial pressure was maintained between 70 and 90 mmHg during anesthesia. When the instrumentation was finished, the dogs were prepared for surgery. Lactated Ringer's solution was administered intravenously at 5 mL kg−1 hour−1 throughout the study. Laparoscopic surgery to perform bilateral ovariectomy started 60–80 minutes after induction. The laparoscopic procedure was performed using two 5 mm and one 10 mm trocar ports through the linea alba to gain intra-abdominal access. The abdomen was insufflated with CO2 with pressures between 6 and 11 cmH2O. The laparoscopic procedure duration was between 30 and 40 minutes in all dogs. However, the dogs then remained under anesthesia to perform the MAC studies. During the MAC studies, the dogs received maropitant 1 and 5 mg kg−1 IV to test its effect on MAC. At the end of anesthesia, all dogs received one dose of ketoprofen 1 mg kg−1 SQ and hydromorphone 0.1 mg kg−1 SQ for postoperative pain. Cephalexin was administered at 22 mg kg−1 IV to prevent infection. The dogs recovered without complications and were continuously observed for pain until normal behavior returned. One hour after waking up from anesthesia all dogs were comfortable, walking and able to play if allowed. At this time, the dogs returned to their respective runs and were assessed for comfort every hour for the following 3 hours and then twice a day for 5 days. No objective pain assessment was performed during the recovery period but subjectively all dogs were comfortable at all times during the recovery period. Pain and stress could predispose to further GI dysfunction (Konturek et al. 2011).

The data are presented as median (range) and were not normally distributed. The individual control values were compared to the anesthetized values using the Mann–Whitney test in the same dog (Prism4; GraphPad software Inc., CA, USA). Then, the anesthetized values were compared to the anesthesia + surgery values using the Mann-Whitney test as well. A < 0.05 was considered significant. Normally distributed data are reported as mean ± SD.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Anesthesia was maintained for a median 8.5 (4.75–9.75) hours for the gastric group and 8.5 (8–10) hours for the small bowel group to perform the MAC study. The mean end-tidal sevoflurane concentration not corrected to sea level during the anesthesia period in both groups was 2.3 ± 0.5%. No complications were observed at any time in any dog during the studies. The study was performed at 1524 m of elevation from sea level (5003 feet).

Gastric study

In eight dogs, anesthesia reduced gastric propulsive motility within 20 minutes of anesthesia induction. The strength of gastric contractions, represented by the maximum and mean pressure amplitudes, decreased from 52 (13–94) and 11 (8–20) mmHg respectively in the awake dogs to 8 (3–55) and 3 (1–10) mmHg in the anesthetized dogs (< 0.01; Table 1; Fig. 1). The calculated motility index decreased during anesthesia from 0.63 (0–1.58) to 0 mmHg (0–0.31; < 0.01).

Table 1. Median (range) parameters for gastric activity (Eight dogs)
 AwakeAnesthesiap value
  1. Max Ampl Contrac, maximum amplitude of gastric contractions; Mean Ampl Contrac, mean peak amplitude of gastric contractions; Freq of Contrac, frequency of contractions recorded per minute; Motility Index, which is the area under the curve of gastric contractions greater than 10 mmHg divided by time (mmHg); GET, which is the gastric emptying time and is the lag time of the WMC in the stomach.

pH2.05 (0.8–3.1)2.1 (1.2–3.5)0.32
Max Ampl Contrac (mmHg)52 (13–94)8 (3–55)<0.01
Mean Ampl Contrac (mmHg)11 (8–20)3 (1–10)<0.01
Freq of Contrac minute−13.7 (1.6–4.4)2.8 (0.1–5.1)0.1
Motility index (mmHg)0.63 (0–1.58)0 (0–0.31)<0.01
GET (hours)12 (5.3–16)49 (9.75–56.25)<0.01
image

Figure 1. Effect of sevoflurane anesthesia on gastric activity. The top figure shows the WMC recordings while the dog was awake (control). The bottom figure shows the WMC recordings before, during and after anesthesia. Notice the prolonged GET during anesthesia. The black line is pH and the grey lines along the x-axis are intraluminal pressure. The bar underneath ‘Anesthesia Duration’ indicates the anesthesia time from induction until extubation. The bar underneath ‘Lap Sx’ indicates the duration of laparoscopic surgery. GET, gastric emptying time; SB, small bowel transit time; LB, large bowel transit time.

Download figure to PowerPoint

Neither the frequency of gastric contractions nor the pH within the gastric lumen changed with anesthesia (Table 1). The number of gastric contractions when awake was 3.7 (1.6–4.4) and during anesthesia was 2.8 (0.1–5.1) contractions minute−1 (p = 0.1). The average gastric pH in the awake dogs was 2.05 (0.8–3.1) and this remained constant during anesthesia at 2.1 (1.2–3.5; = 0.32).

GET was 12 (5.3–16) hours in the awake dogs and increased to 49 (9.75–56.25) hours when the dogs were anesthetized for 8 hours (< 0.01; Table 1). Gastric motility pressure amplitude and motility index did not return to the awake values until 12–15 hours after the dogs recovered from anesthesia (Fig. 1).

We compared gastric activity during the actual time of laparoscopic surgery to that before surgery while still under anesthesia. No difference was observed regarding force or frequency of luminal contractions, motility index or pH with laparoscopic surgery (data not shown).

Small bowel study

In four dogs, anesthesia decreased small bowel propulsive motility within 20 minutes of anesthesia induction. The maximum and mean pressure amplitudes decreased from 75 (56–215) and 34 (24–37) mmHg in the awake dogs to 13 (3–82) and 3 (0.9–17) mmHg in the anesthetized dogs (= 0.02 and = 0.02; Table 2; Fig. 2). The calculated motility index decreased during anesthesia from 3.75 (1–4.56) to 0 (0–1.53; = 0.02).

Table 2. Median (range) parameter for small bowel activity (four dogs)
 AwakeAnesthesiap value
  1. Max Ampl Contrac, maximum amplitude of small bowel contractions; Mean Ampl Contrac, mean peak amplitude of small bowel contractions; Freq of Contrac, frequency of contractions recorded; Motility Index, which is the calculation of the small bowel contractions amplitude area under the curve divided by time; Transit Time, which is the lag time of the WMC in the small bowel.

pH7.55 (6–7.8)7.15 (6–7.9)0.34
Max Ampl Contrac (mmHg)75 (56–215)13 (3–82)0.02
Mean Ampl Contrac (mmHg)34 (24–37)3 (0.9–17)0.02
Freq of Contrac minute−10.5 (0.3–1.4)1.4 (0.3–4.6)0.11
Motility index3.75 (1–4.56)0 (0–1.53)0.02
Transit Time (hours)2.75 (2–3.75)11.5 (6–14.25)0.03
image

Figure 2. Effect of sevoflurane anesthesia on small bowel activity. The top figure shows the WMC recordings while the dog was awake (control). The bottom figure shows the WMC recordings before, during and after anesthesia. Notice the prolonged SB during anesthesia. The black line depicts pH and the grey lines along the x-axis are intraluminal pressure. The bar underneath ‘Anesthesia Duration’ indicates the anesthesia time from induction until waking up. The bar underneath ‘Lap Sx’ indicates the duration of laparoscopic surgery for ovariectomy. GET, gastric emptying time; SB, small bowel transit time; LB, large bowel transit time.

Download figure to PowerPoint

Similar to the gastric data, the small bowel frequency of contractions and pH did not change with anesthesia. The frequency of small bowel contractions was 0.5 (0.3–1.4) in the awake dogs, which did not change during anesthesia 1.4 (0.3–4.6) contractions minute−1 (= 0.11; Table 2). The small bowel intraluminal pH was 7.55 (6–7.8) in the awake dogs and 7.15 (6–7.9) in the anesthetized dogs (= 0.34; Table 2).

In contrast to gastric motility, small bowel motility returned to the awake values within 2 hours following recovery from anesthesia (Fig. 2). We compared the small bowel activity during the actual time of laparoscopic surgery and before surgery while under anesthesia. No difference was observed regarding force or frequency of luminal contractions, motility index or pH with laparoscopic surgery (data not shown).

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

In the present study, we showed that prolonged general anesthesia with sevoflurane for laparoscopy surgery decreased both gastric and small bowel propulsive motility in dogs. Anesthesia with laparoscopy decreased the force of contractions and induced a 30–40 hour delay in GET.

The GI contraction forces during anesthesia decreased to 20–30% of that seen in control awake dogs, thereby impairing the propulsive motility of both the stomach and small bowel. The frequency of contractions in the stomach and small bowel did not change with anesthesia. The stress of anesthesia, surgery and the increase in inflammatory mediators during surgery may be some of the mechanisms involved in decreasing the force of contractions as previously reviewed (Carroll & Alavi 2009). A disadvantage of the technique used in this study is that the WMC technology cannot determine whether the normal peristaltic or segmental contractions were affected, or if the inter-digestive migratory motor complexes were diminished during anesthesia and surgery. Previous studies examining the GI tract myoelectrical activity during anesthesia showed a decrease in amplitude and duration for slow waves, phasic contractions and interdigestive motor complexes, suggesting a general disruption of the neurocrine system and potentially the interstitial cells of Cajal (Schurizek et al. 1989; Lester et al. 1992; Yanagida et al. 2004). An additional disadvantage of the technique is the cost (one WMC costs around $600). Thus monitoring GI propulsive motility routinely during anesthesia using the WMC is expensive.

The results of this study are similar to human studies with other inhaled anesthetics, such as enflurane and halothane. These inhaled anesthetic agents decreased the force of contractions and delayed gastric emptying without changing the frequency of contractions (Schurizek et al. 1989).

Previous studies in humans suggest that the choice of anesthetic technique had little impact on the incidence of GI dysfunction, post-anesthetic GI complications or the time to hospital discharge (Schurizek et al. 1989; Jensen et al. 1992; Freye et al. 1998; Scrivani et al. 1998; Lee et al. 1999; Liao et al. 2003). Two earlier studies suggest that pentobarbital and thiopental had little influence on the dog's GI tract due to a potential parasympathetic effect (Bueno et al. 1978; Healy et al. 1981). In addition, one study showed that analgesic or anesthetic ketamine doses did not influence GI motility in dogs (Fass et al. 1995). However, morphine, meperidine, atropine, thiopental, ether and halothane decrease GI activity in dogs (Tinckler 1965; Healy et al. 1981). For these reasons, we are inclined to believe that most inhaled or injectable anesthetics except nitrous oxide, some barbiturates and ketamine may have similar effects on the GI tract. Further studies are necessary to identify and compare different anesthetic techniques and drugs.

The clinical relevance of the study is that long periods of anesthesia and surgery may cause a significant delay in gastric emptying and predispose to post-anesthetic GI complications such POI, gastro-esophageal reflux, gastric stasis, vomiting or gastric dilatation and volvulus. Studies in humans showed that small bowel motility returns within hours after waking up from general anesthesia, while the stomach may take 1–2 days to return to normal activity (Behm & Stollman 2003). In this particular study, we did not address large bowel motility, but, in humans large intestinal motility returns to normal activity 2–3 days after recovery from anesthesia (Behm & Stollman 2003). In addition to anesthesia, fluid therapy using higher fluid rates in anesthetized humans during abdominal surgical procedures predisposed to GI propulsive motility delays (Lobo et al. 2002; Nisanevich et al. 2005; McArdle et al. 2009). In the current study, all dogs received 5 mL kg−1 hour−1 of lactated Ringer's solution throughout the study and we do not know how this fluid rate impacted the GI disturbance observed.

In the study there were a number of variables that could have influenced our results in terms of clinical relevance. The dogs in the study were not fasted before anesthesia. The impact of fasting on GI motility in anesthetized dogs is unknown. The dogs in the study were anesthetized for long periods of time (5–10 hours) because the anesthesia protocol was within the design of a MAC study performed simultaneously (Boscan et al. 2011a,b). However, anesthetizing dogs for 2.5–3 hours with pentobarbital showed similar decreased GI tract motility that lasted 13 hours, which is equivalent to what we found in the gastric group (Furuta et al. 2002). However, it is unknown if shorter anesthesia periods will have different effects on the GI tract. In this study, sevoflurane and maropitant were the only drugs used during anesthesia but hydromorphone and cephalexin were administered at the end of anesthesia. Hydromorphone is an opioid and decreases GI propulsive motility. Hydromorphone likely played an important role on the results obtained during the recovery period. Maropitant is an antiemetic approved for dogs and a preliminary study showed that maropitant had no effect on GI propulsive motility in the stomach, small or large bowel of dogs (McCord et al. 2009). However, we do not know how maropitant could have impacted the results in the study. The dogs in our study were all young, healthy females, therefore conclusions cannot be drawn regarding the effect of anesthesia on GI motility on geriatric or compromised dogs or even different breeds. In the present study a laparoscopic ovariectomy was performed, but because general anesthesia alone severely diminished the force of gastric and small bowel contractions, surgery was not found to suppress the force of contractions any further. Previous studies have shown that laparoscopic surgery has fewer effects on GI activity in dogs when compared to laparotomy (Bohm et al. 1995; Davies et al. 1997). In the present study, both gastric and small bowel motility were significantly suppressed after anesthesia induction. For this reason, we were not able to evaluate the effect of laparoscopy surgery on gastric and small bowel motility. However, this does not imply that laparoscopy surgery does not have further deleterious effects.

The technique used to assess GI motility is a novel technique in veterinary medicine. It is validated in dogs but larger studies are necessary to better understand the data obtained and potential drawbacks of the technology. For example, the WMC is a large, indigestible object that may have problems moving through the GI tract, especially through the pyloric sphincter. A direct comparison between WMC and scintigraphy in dogs showed comparable results and similar variability between techniques (Boillat et al. 2010a,b).

In conclusion, prolonged general anesthesia with sevoflurane for laparoscopy reduces both gastric and small intestinal propulsive motility in dogs. Gastric motility is more severely affected and does not recover until 12–15 hours following anesthesia. This effect on gastric propulsive motility translates into a 30–40 hour gastric emptying delay or POI. The effect of prolonged anesthesia on GI motility may predispose to further GI complications that should be carefully monitored during the recovery period.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Thanks to Dr. K. Mama for editing the manuscript.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  • Andersen MS, Clark L, Dyson SJ et al. (2006) Risk factors for colic in horses after general anaesthesia for MRI or nonabdominal surgery: absence of evidence of effect from perianaesthetic morphine. Equine Vet J 38, 368374.
  • Bardon T, Ruckebusch Y (1985) Comparative effects of opiate agonists on proximal and distal colonic motility in dogs. Eur J Pharmacol 110, 329334.
  • Behm B, Stollman N (2003) Postoperative ileus: etiologies and interventions. Clin Gastroenterol Hepatol 1, 7180.
  • Bohm B, Milsom JW, Fazio VW (1995) Postoperative intestinal motility following conventional and laparoscopic intestinal surgery. Arch Surg 130, 415419.
  • Boillat CS, Gaschen FP, Gaschen L et al. (2010a) Variability associated with repeated measurements of gastrointestinal tract motility in dogs obtained by use of a wireless motility capsule system and scintigraphy. Am J Vet Res 71, 903908.
  • Boillat CS, Gaschen FP, Hosgood GL (2010b) Assessment of the relationship between body weight and gastrointestinal transit times measured by use of a wireless motility capsule system in dogs. Am J Vet Res 71, 898902.
  • Boscan P, van Hoogmoed LM, Farver TB et al. (2006) Evaluation of the effects of the opioid agonist morphine on gastrointestinal tract function in horses. Am J Vet Res 67, 992997.
  • Boscan P, Monnet E, Mama K et al. (2011a) A dog model to study ovary, ovarian ligament and visceral pain. Vet Anaesth Analg 38, 260266.
  • Boscan P, Monnet E, Mama K et al. (2011b) Effect of maropitant, a neurokinin-1 receptor antagonist, on anesthetic anesthetic requirements during noxious visceral stimulation of the ovary in dogs. Am J Vet Res 72, 15761579.
  • Bueno L, Fioramonti J, Ruckebusch Y (1978) Postoperative intestinal motility in dogs and sheep. Am J Dig Dis 23, 682689.
  • Carroll J, Alavi K (2009) Pathogenesis and management of postoperative ileus. Clin Colon Rectal Surg 22, 4750.
  • Davies W, Kollmorgen CF, Tu QM et al. (1997) Laparoscopic colectomy shortens postoperative ileus in a canine model. Surgery 121, 550555.
  • Durongphongtorn S, McDonell WN, Kerr CL et al. (2006) Comparison of hemodynamic, clinicopathologic, and gastrointestinal motility effects and recovery characteristics of anesthesia with isoflurane and halothane in horses undergoing arthroscopic surgery. Am J Vet Res 67, 3242.
  • Fass J, Bares R, Hermsdorf V et al. (1995) Effects of intravenous ketamine on gastrointestinal motility in the dog. Intensive Care Med 21, 584589.
  • Freye E, Sundermann S, Wilder-Smith OH (1998) No inhibition of gastro-intestinal propulsion after propofol- or propofol/ketamine-N2O/O2 anaesthesia. A comparison of gastro-caecal transit after isoflurane anaesthesia. Acta Anaesthesiol Scand 42, 664669.
  • Furuta Y, Takeda M, Nakayama Y et al. (2002) Effects of SK-896, a new human motilin analogue ([Leu13]motilin-Hse), on postoperative ileus in dogs after laparotomy. Biol Pharm Bull 25, 10631071.
  • Graves GM, Becht JL, Rawlings CA (1989) Metoclopramide reversal of decreased gastrointestinal myoelectric and contractile activity in a model of canine postoperative ileus. Vet Surg 18, 2733.
  • Healy TEJ, Foster GE, Evans DF et al. (1981) Effect of some IV anaesthetic agents on canine gastrointestinal motility. Br J Anaesth 53, 229233.
  • Jensen AG, Kalman SH, Nystrom PO et al. (1992) Anaesthetic technique does not influence postoperative bowel function: a comparison of propofol, nitrous oxide and isoflurane. Can J Anaesth 39, 938943.
  • Konturek PC, Brzozowski T, Konturek SJ (2011) Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options. J Physiol Pharmacol 62, 591599.
  • Kuo B, McCallum RW, Koch K et al. (2007) SmartPill®, A Novel Ambulatory Diagnostic Test For Measuring Gastric Emptying In Health and Disease. The SmartPill® Corporation, Buffalo, NY.
  • Lee TL, Ang SB, Dambisya YM et al. (1999) The effect of propofol on human gastric and colonic muscle contractions. Anesth Analg 89, 12461249.
  • Lester GD, Bolton JR, Cullen LK et al. (1992) Effects of general anesthesia on myoelectric activity of the intestine in horses. Am J Vet Res 53, 15531557.
  • Liao Q, Wang MA, Ouyang W (2003) Effect of different anesthesias on gastrointestinal motility after laparoscopic cholecystectomy. Hunan Yi Ke Da Xue Xue Bao 28, 7375.
  • Little D, Redding WR, Blikslager AT (2001) Risk factors for reduced postoperative fecal output in horses: 37 cases (1997-1998). J Am Vet Med Assoc 218, 414420.
  • Lobo DN, Bostock KA, Neal KR et al. (2002) Effect of salt and water balance on recovery of gastrointestinal function after elective colonic resection: a randomized controlled trial. Lancet 359, 18121818.
  • Maron DJ, Fry RD (2008) New therapies in the treatment of postoperative ileus after gastrointestinal surgery. Am J Ther 15, 5965.
  • McArdle GT, McAuley DF, McKinley A et al. (2009) Preliminary results of a prospective randomized trial of restrictive versus standard fluid regime in elective open abdominal aortic aneurysm repair. Ann Surg 250, 2834.
  • McCord KW, Boscan P, Dowers K et al. (2009) Comparison of gastrointestinal motility in dogs treated with metoclopramide, cisapride, erythromycin or maropitant using the Smartpill. J Vet Intern Med 23, 735.
  • Nisanevich V, Felsenstein I, Almogy G et al. (2005) Effect of intraoperative fluid management on outcome after intraabdominal surgery. Anesthesiology 103, 2532.
  • Parkman HP (2009) Assessment of gastric emptying and small-bowel motility: scintigraphy, breath tests, manometry, and SmartPill. Gastrointest Endosc Clin N Am 19, 4955.
  • Rao SS, Kuo B, McCallum RW et al. (2009) Investigation of colonic and whole-gut transit with wireless motility capsule and radiopaque markers in constipation. Clin Gastroenterol Hepatol 7, 537544.
  • Roger T, Bardon T, Ruckebusch Y (1994) Comparative effects of mu and kappa opiate agonists on the cecocolic motility in the pony. Can J Vet Res 58, 163166.
  • Sarosiek I, Majewski M (2007) Non-Digestible Capsule (Smartpill®) As A Novel Diagnostic Tool For Detecting Motility Impairment Within The Gut. The SmartPill® Corporation, Buffalo, NY.
  • Savas I, Plevraki K, Raptopoulos D (2001) Aerophagia and gastric dilation following tiletamine/zolazepam anaesthesia in a dog. Vet Rec 149, 2021.
  • Schurizek BA, Willacy LH, Kraglund K et al. (1989) Effects of general anaesthesia with halothane on antroduodenal motility, pH and gastric emptying rate in man. Br J Anaesth 62, 129137.
  • Scrivani PV, Bednarski RM, Myer CW (1998) Effects of acepromazine and butorphanol on positive-contrast upper gastrointestinal tract examination in dogs. Am J Vet Res 59, 12271233.
  • Senior JM, Pinchbeck GL, Allister R et al. (2006) Post anaesthetic colic in horses: a preventable complication? Equine Vet J 38, 479484.
  • Tinckler LF (1965) Surgery and intestinal motility. Surgical Res 52, 140145.
  • Toll PW, Yamka RM, Schoenherr WD et al. (2010) Obesity. In: Small Animal Clinical Nutrition (5th edn). Hand MS, Thatcher CD, Remillard RL, et al. (eds). Mark Morris Institute, Topeka, KS, USA. pp. 501535.
  • Trudel L, Bouin M, Tomasetto C et al. (2003) Two new peptides to improve post-operative gastric ileus in dog. Peptides 24, 531534.
  • Van der Gaag I, Happe RP, Okkens AC et al. (1981) Enterological complications following ovariohysterectomy in dogs. Tijdschr Diergeneeskd 106, 11991207.
  • Wood JD, Galligan JJ (2004) Function of opioids in the enteric nervous system. Neurogastroenterol Motil 16, 1728.
  • Yanagida H, Yanase H, Sanders KM et al. (2004) Intestinal surgical resection disrupts electrical rhythmicity, neural responses, and interstitial cell networks. Gastroenterology 127, 17481759.