Minimally invasive wireless motility capsule to study canine gastrointestinal motility and pH

Canine Mucosal Artificial Colon: development of a new colonic in vitro model adapted to dog sizes

Differences in dog breed sizes are an important determinant of variations in digestive physiology, mainly related to the large intestine. In vitro gut models are increasingly used as alternatives to animal experiments for technical, cost, societal, and regulatory reasons. Up to now, only one in vitro model of the canine colon incorporates the dynamics of different canine gut regions, yet no adaptations exist to reproduce size-related digestive parameters. To address this limitation, we developed a new model of the canine colon, the CANIne Mucosal ARtificial COLon (CANIM-ARCOL), simulating main physiochemical (pH, transit time, anaerobiosis), nutritional (ileal effluent composition), and microbial (lumen and mucus-associated microbiota) parameters of this ecosystem and adapted to three dog sizes (i.e., small under 10 kg, medium 10-30 kg, and large over 30 kg). To validate the new model regarding microbiota composition and activities, in vitro fermentations were performed in bioreactors inoculated with stools from 13 dogs (4 small, 5 medium, and 4 large). After a stabilization period, microbiota profiles clearly clustered depending on dog size. Bacteroidota and Firmicutes abundances were positively correlated with dog size both in vitro and in vivo, while opposite trends were observed for Actinobacteria and Proteobacteria. As observed in vivo, microbial activity also increased with dog size in vitro, as evidenced from gas production, short-chain fatty acids, ammonia, and bile acid dehydroxylation. In line with the 3R regulation, CANIM-ARCOL could be a relevant platform to assess bilateral interactions between food and pharma compounds and gut microbiota, capturing inter-individual or breed variabilities. KEY POINTS: • CANIM-ARCOL integrates main canine physicochemical and microbial colonic parameters • Gut microbiota associated to different dog sizes is accurately maintained in vitro • The model can help to move toward personalized approach considering dog body weight.

Diagnostic Methods for Evaluation of Gastric Motility-A Mini Review

Gastric motility abnormalities are common in patients with disorders of gut-brain interaction, such as functional dyspepsia and gastroparesis. Accurate assessment of the gastric motility in these common disorders can help understand the underlying pathophysiology and guide effective treatment. A variety of clinically applicable diagnostic methods have been developed to objectively evaluate the presence of gastric dysmotility, including tests of gastric accommodation, antroduodenal motility, gastric emptying, and gastric myoelectrical activity. The aim of this mini review is to summarize the advances in clinically available diagnostic methods for evaluation of gastric motility and describe the advantages and disadvantages of each test.

Wireless Monitoring of Gastrointestinal Transit Time, Intra-luminal pH, Pressure and Temperature in Experimental Pigs: A Pilot Study

BACKGROUND

There is no single gold standard for investigation of gastrointestinal motility function. Wireless motility monitoring involves a novel concept which provides a complex information on gastrointestinal function (gastrointestinal transit time, intra-luminal pH, pressure and temperature). Gastrointestinal motility functions of experimental pigs are very similar to those of humans. That is why porcine studies have already provided suitable experimental models for several preclinical projects.

AIMS

The aim of our study was to adopt methods of non-invasive wireless monitoring of gastrointestinal functions in experimental pigs.

METHODS

Five experimental adult female pigs were enrolled into the study. Wireless motility capsules were delivered into the porcine stomach endoscopically. Gastrointestinal transit and intra-luminal conditions were recorded for five days.

RESULTS

Records of animals provided good (3 pigs) or very good quality files (2 pigs). 31150 variables were evaluated. Mean time of the presence of capsules in the stomach was 926 ± 295 min, transfer of a capsule from the stomach into the duodenum lasted 5-34 min. Mean small intestinal transit time was 251 ± 43 min. Food intake was associated with an increase of gastric luminal temperature and a decrease of intra-gastric pressure. The highest intra-luminal pH was present in the ileum. The highest temperature and the lowest intra-luminal pressure were found in the colon. All data displayed a substantial inter-individual variability.

CONCLUSIONS

This pilot study has proven that a long-term function monitoring of the gastrointestinal tract by means of wireless motility capsules in experimental pigs is feasible. However, both ketamine-based induction of general anaesthesia as well as long-lasting general anaesthesia (> 6 hours) should be avoided to prevent retention of a capsule in the porcine stomach.

Evaluation of gastrointestinal transit times and pH in healthy cats using a continuous pH monitoring system

OBJECTIVES

The aim of this study was to characterize gastrointestinal (GI) transit times and pH in healthy cats.

METHODS

GI transit times and pH were measured in six healthy, colony-housed, purpose-bred spayed female cats using a continuous, non-invasive pH monitoring system in a sequential order design. For the first period ('pre-feeding'), food was withheld for 20 h, followed by oral administration of a pH capsule. Five hours post-capsule administration, cats were meal-fed by offering them their daily allowance of food for 1 h. For the second period ('post-feeding'), food was withheld for 24 h and cats were fed for 1 h, after which a pH capsule was orally administered. Studies in both periods were repeated three times. GI transit times and pH were compared between the two periods.

RESULTS

The median transit times for the pre- and post-feeding periods, respectively, were: gastric - 94 mins (range 1-4101) and 1068 mins (range 484-5521); intestinal - 1350 mins (range 929-2961) and 1534 mins (range 442-2538); and GI - 1732 mins (range 1105-5451) and 2795 mins (range 926-6563). The median GI pH values for the first and second periods, respectively, were: esophageal - 7.0 (range 3.5-7.8) and 4.5 (range 2.9-6.4); gastric - 2.7 (range 1.7-6.2) and 2.0 (range 1.1-3.3); intestinal - 8.2 (range 7.6-8.7) and 7.8 (range 6.7-8.5); first-hour small intestinal - 8.2 (range 7.4-8.7) and 8.3 (range 7.9-8.6); and last-hour large intestinal - 8.5 (range 7.0-8.9) and 7.8 (range 6.3-8.7). Gastric (P <0.0020) and intestinal pH (P <0.0059) were significantly increased in the pre-feeding period compared with the post-feeding period.

CONCLUSIONS AND RELEVANCE

Gastric and intestinal pH differed significantly when the capsule was administered 5 h prior to feeding compared with 1 h after feeding. Transit times for both periods showed high degrees of intra- and inter-individual variability.

Gastrointestinal transit time is faster in Beagle dogs compared to cats

OBJECTIVE

To characterize gastrointestinal transit times (GITTs) and pH in dogs, and to compare to data recently described for cats.

ANIMALS

7 healthy, colony-housed Beagles.

PROCEDURES

The GITTs and pH were measured using a continuous pH monitoring system. For the first period (prefeeding), food was withheld for 20 hours followed by pH capsule administration. Five hours after capsule administration, dogs were offered 75% of their historical daily caloric intake for 1 hour. For the second period (postfeeding), food was withheld for 24 hours. Dogs were allowed 1 hour to eat, followed by capsule administration. Both periods were repeated 3 times. The GITTs and pH were compared to published feline data.

RESULTS

The mean ± SD transit times in dogs for the pre- and postfeeding periods, respectively, were esophageal, 3 ± 5 minutes and 13 ± 37 minutes; gastric, 31 ± 60 minutes and 829 ± 249 minutes; and intestinal, 795 ± 444 minutes and 830 ± 368 minutes. The mean ± SD gastrointestinal pH in dogs for the pre- and postfeeding periods, respectively, were esophageal, 6.6 ± 0.6 and 5.7 ± 1.0; gastric, 3.0 ± 1.4 and 1.8 ± 0.3; intestinal, 7.9 ± 0.3 and 7.7 ± 0.6; first-hour small intestinal, 7.6 ± 0.5 and 7.1 ± 0.4; and last-hour large intestinal, 7.9 ± 0.6 and 7.7 ± 1.0. The first-hour small intestinal pH and total transit times varied between dogs and cats depending on feed period (P = .002 and P = .04, respectively). Post hoc analysis revealed significantly shorter total transit times in dogs prefeeding (P = .005; mean ± SD for cats, 2,441 ± 1,359 minutes; for dogs, 828 ± 439 minutes) and postfeeding (P = .03; mean ± SD for cats, 3,009 ± 1,220 minutes; for dogs, 1,671 ± 513 minutes). Total transit time for dogs was also shorter pre- versus postfeeding (P = .003).

CLINICAL RELEVANCE

GITT is faster in Beagles compared to cats, but gastrointestinal pH are similar when fed the same diet.

From Chihuahua to Saint-Bernard: how did digestion and microbiota evolve with dog sizes

Health and well-being of dogs are of paramount importance to their owners. Digestion plays a key role in dog health, involving physicochemical, mechanical and microbial actors. However, decades of breeding selection led to various dog sizes associated with different digestive physiology and disease sensitivity. Developing new products requires the consideration of all the multi-faceted aspects of canine digestion, the evaluation of food digestibility, drug release and absorption in the gut. This review paper provides an exhaustive literature survey on canine digestive physiology, focusing on size effect on anatomy and digestive parameters, with graphical representation of data classified as "small", "medium" and "large" dogs. Despite the huge variability between protocols and animals, interesting size effects on gastrointestinal physiology were highlighted, mainly related to the colonic compartment. Colonic measurements, transit time permeability, fibre degradation, faecal short-chain fatty acid concentration and faecal water content increase while faecal bile acid concentration decreases with body size. A negative correlation between body weight and Proteobacteria relative abundance was observed suggesting an effect of dog body size on faecal microbiota. This paper gathers helpful in vivo data for academics and industrials and supports the development of new food and pharma products to move towards canine personalized nutrition and health.

Effects of housing environment on oral absorption of acetaminophen in healthy Beagles

OBJECTIVE

To evaluate the effects of housing environment on oral absorption of acetaminophen in dogs.

ANIMALS

6 healthy Beagles.

PROCEDURES

Acetaminophen (325 mg, PO; mean dose, 31.1 mg/kg) was administered in a crossover study design with dogs housed in their normal environment or in a cage in an unfamiliar environment. There was a 7-day washout period between phases. Blood samples were collected for 24 hours following acetaminophen administration, and plasma acetaminophen concentrations were determined with high-pressure liquid chromatography.

RESULTS

A 2-compartment model with lag time was the best fit for both phases of the study. None of the primary or secondary pharmacokinetic parameters were significantly different between the 2 housing environments.

CLINICAL RELEVANCE

Findings suggested that in dogs, housing environment (normal environment vs a cage in an unfamiliar environment) did not significantly affect oral absorption and, by extension, gastric emptying of acetaminophen.

Ex vivo comparison of hand-sutured versus circular stapled anastomosis in canine large intestine

OBJECTIVE

To compare leakage pressures of colonic anastomoses performed with circular staplers to conventional hand-sewn techniques in dogs.

STUDY DESIGN

Ex-vivo study.

ANIMALS

Colon from 11 canine cadavers.

METHODS

Thirty-two colonic anastomoses were performed. Four segments from each colon were randomly assigned to one of four techniques: hand-sewn colonic anastomoses performed with 4-0 glycomer 631 (G) and 4-0 barbed glycomer 631 (BG), and circular stapled colonic anastomoses using 4.8 mm End-to-End Anastomosis (EEA C4.8mm) and 3.5 mm End-to-End Anastomosis (EEA C3.5mm), 21 mm diameter circular staples in cadaveric canine colon. Leakage pressure was defined as the pressure at which dye-containing solution was first observed to leak from the anastomosis site.

RESULTS

Leakage pressures were 49.5 mmHg (range:16-72) in group G, 45.5 mmHg (range:19-80) in group BG, 5.3 mmHg (range:0-31) in group C3.5mm, and 29.5 mmHg (range:23-50.3) in group C4.8mm. Anastomoses leaked at lower pressures when stapled rather than hand-sewn (C4.8mm-G p = .0313, C4.8mm-BG p = .0131, C3.5mm-G p = .0469, C3.5mm-BG p = .0313). Two of the C3.5mm constructs leaked immediately after saline infusion with 4/6 leaking at <5.3 mmHg.

CONCLUSION

End-to-end colonic anastomoses closed with circular stapler leaked at lower pressures than hand-sutured anastomoses. Use of the EEA stapler with a staple height of 3.5 mm did not result in safe colonic anastomoses.

CLINICAL SIGNIFICANCE

These results provide evidence to support hand-suturing colonic anatomoses with G and BG in dogs. The 4.8 mm staples may be considered in anatomical locations difficult to reach.

Feasibility, complications, and quality of visualization using video capsule endoscopy in 40 dogs with overt or questionable gastrointestinal bleeding

Background

Prospective studies describing video capsule endoscopy (VCE), its feasibility, and complications in dogs are limited.

Objective

To assess VCE, quality of visualization, complications, and risk factors for incomplete studies in dogs with overt or questionable gastrointestinal bleeding (GIB).

Animals

Forty dogs with overt or questionable GIB.

Methods

Prospective, multicenter, interventional study. From August 2017 to March 2020, dogs were examined by VCE (ALICAM) because of overt or questionable GIB. Reported outcomes included diagnostic results of VCE study, quality of visualization, and complications. Risk factors for incomplete studies were evaluated using logistic regression.

Results

In total, 40 dogs (13 overt, 27 questionable GIB) were included. The capsules were administered PO in 29 and endoscopically in 11 dogs (6 duodenum, 5 stomach). One capsule was not retrieved. In 24 of 39 recordings, bleeding lesions were identified (10 overt GIB, 14 questionable GIB). Overall, the quality of visualization was poor to limited in the stomach and colon, and adequate to good in the small intestine. The most common complication was an incomplete study in 15/39 studies, particularly after oral administration (13/28). Risk factors for incomplete study after oral administration included administration of simethicone or opioids, chronic enteropathy, and capsule gastric transit time >6 hours.

Conclusions and Clinical Importance

Video capsule endoscopy can be used to diagnose a variety of lesions causing bleeding in the gastrointestinal tract of dogs with questionable GIB. Incomplete studies are the most common complications in dogs after oral administration of capsules.

Comparison of Canine and Human Physiological Factors: Understanding Interspecies Differences that Impact Drug Pharmacokinetics

This review is a summary of factors affecting the drug pharmacokinetics (PK) of dogs versus humans. Identifying these interspecies differences can facilitate canine-human PK extrapolations while providing mechanistic insights into species-specific drug in vivo behavior. Such a cross-cutting perspective can be particularly useful when developing therapeutics targeting diseases shared between the two species such as cancer, diabetes, cognitive dysfunction, and inflammatory bowel disease. Furthermore, recognizing these differences also supports a reverse PK extrapolations from humans to dogs. To appreciate the canine-human differences that can affect drug absorption, distribution, metabolism, and elimination, this review provides a comparison of the physiology, drug transporter/enzyme location, abundance, activity, and specificity between dogs and humans. Supplemental material provides an in-depth discussion of certain topics, offering additional critical points to consider. Based upon an assessment of available state-of-the-art information, data gaps were identified. The hope is that this manuscript will encourage the research needed to support an understanding of similarities and differences in human versus canine drug PK.

Evaluation of gastric motility in nine dogs before and after prophylactic laparoscopic gastropexy: a pilot study

BACKGROUND

The purpose of this study was to evaluate the effect of a prophylactic laparoscopic gastropexy on gastric motility in healthy large-breed dogs.

METHODS

This was a prospective pilot study with nine healthy client-owned dogs. Each dog was its own control. Gastric motility was evaluated before and after laparoscopic gastropexy. Dogs were fed a standard diet three weeks before and after surgery. Gastric motility was measured before and 3 weeks after surgery. A wireless motility capsule (WMC) was used to measure gastric pH, intragastric pressure, temperature, frequency of contractions, motility index (MI) and transit time. Non-parametric statistical analysis was used to compare the paired data. Clients were contacted for follow-up information 2 years postoperatively.

RESULTS

Median frequency of gastric contractions was 1.3 (range, 0.6-1.9 contractions/min) before gastropexy and 1.0 (range, 0.3-2.6 contractions/min) after gastropexy (P = 0.820). Median MI was 49.2 (range, 23.7-96.6) before gastropexy and 28.1 (range, 12.2-148.9) after gastropexy (P = 0.652). Median gastric emptying time was 1140 (range, 486-1230 min) before gastropexy and 1110 (range, 306-2610 min) after gastropexy (P = 0.570). During the hour before the WMC passed through the pylorus, median MI was 72.2 (range, 48.2-549.3) before gastropexy and 52.9 (range, 15.20-322.8) after gastropexy (P = 0.734), and frequency of contractions was 1.1 (range, 0.9-4.1 contractions/min) before gastropexy and 1.2 (range, 0.5-3.0 contractions/min) after gastropexy (P = 0.652).

CONCLUSION

Motility in the stomach did not change in healthy dogs after prophylactic laparoscopic gastropexy. We conclude that preventive laparoscopic gastropexy does not induce gastroparesis.

Utility of animal gastrointestinal motility and transit models in functional gastrointestinal disorders

Alteration in the gastrointestinal (GI) motility and transit comprises an important component of the functional gastrointestinal disorders (FGID). Available animal GI motility and transit models are to study symptoms (delayed gastric emptying, constipation, diarrhea) rather than biological markers to develop an effective treatment that targets the underlying mechanism of altered GI motility in patients. Animal data generated from commonly used methods in human like scintigraphy, breath test and wireless motility capsule may directly translate to the clinic. However, species differences in the control mechanism or pharmacological responses of GI motility may compromise the predictive and translational value of the preclinical data to human. In this review we aim to provide a summary on animal models used to mimic GI motility alteration in FGID, and the impact of the species differences in the physiological and pharmacological responses on the translation of animal GI motility and transit data to human.

Close association between abnormal expressed enzymes of energy metabolism and diarrhea-predominant irritable bowel syndrome

Background:

Irritable bowel syndrome (IBS) is one of the most common functional intestinal diseases, but its pathogenesis is still unknown. The present study aimed to screen the differentially expressed proteins in the mucosa of colon between IBS with diarrhea (IBS-D) patients and the healthy controls.

Methods:

Forty-two IBS-D patients meeting the Rome III diagnostic criteria and 40 control subjects from July 2007 to June 2009 in Chinese PLA General Hospital were enrolled in the present study. We examined the protein expression profiles in mucosa of colon corresponding to IBS-D patients (n = 5) and controls (n = 5) using 2-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS). Secondly, Western blot and immunohistochemical analysis were carried out to validate the screened proteins in 27 IBS-D patients and 27 controls. Thirdly, high-performance liquid chromatography (HPLC) was further carried out to determine ATP concentration in the mucosa of colon between 10 IBS-D patients and 8 controls. Comparisons between 2 groups were performed by Student's t-test or Mann-Whitney U-test.

Results:

Twelve differentially expressed proteins were screened out. The α-enolase (ENOA) in the sigmoid colon (0.917 ± 0.007 vs. 1.310 ± 0.100, t = 2.643, P = 0.017) and caecum (0.765 ± 0.060 vs. 1.212 ± 0.122, t = 2.225, P = 0.023), Isobutyryl-CoA dehydrogenase (ACAD8) in the sigmoid colon (1.127 ± 0.201 vs. 1.497 ± 0.392, t = 7.093, P = 0.008) of the IBS-D group were significantly lower while acetyl-CoA acetyltransferase (CT) in the caecum (2.453 ± 0.422 vs. 0.931 ± 0.652, t = 8.363, P = 0.015) and ATP synthase subunit d (ATP5H) in the sigmoid (0.843 ± 0.042 vs. 0.631 ± 0.042, t = 8.613,P = 0.007) of the IBS-D group was significantly higher, compared with the controls. The ATP concentration in the mucosa of the sigmoid colon in IBS-D group was significantly lower than that of control group (0.470 [0.180, 1.360] vs. 5.350 [2.230, 7.900], U = 55, P < 0.001).

Conclusions:

Many proteins related to energy metabolism presented differential expression patterns in the mucosa of colon of the IBS-D patients. The abnormalities in energy metabolism may be involved in the pathogenesis of IBS which deserves more studies to elucidate.