Gastro-intestinal motor disturbances induced by lysine-acetylsalicylate treatment in sheep

The effects of intravenous (i.v.), intramuscular (i.m.) and oral administration of lysine-acetylsalicylate (Lys-ASA) on gastro-intestinal motility were investigated in sheep using electromyography. A dose of 20 mg/kg Lys-ASA intravenously reduced the frequency of reticular contractions for 86 ± 18 min, produced abomasal hypomotility and caused a disruption of the cyclical pattern of intestinal motility for at least 120 min. The frequency of reticular contractions measured from 20 to 30 min after Lys-ASA administration was negatively correlated (ß= 0.97; PΔ0.01) to the log of the dose used for doses varying from 10 to 40 mg/kg. Similar effects were observed with intramuscular and oral dose rates of 40 and 80 mg/kg, respectively. Previous i.v. administration of phentolamine (0.1 mg/kg) or tolazoline (2 mg/kg) abolished the effects of Lys-ASA (20 mg/kg) administered intravenously on both reticular contractions and abomaso-intestinal motility.
It was concluded that Lys-ASA administered at therapeutic doses in sheep produced gastro-intestinal motor disturbances and that α-and α₂-adrenergic antagonists are able to block them.     

Loperamide: evidence for a centrally mediated opioid effect on rumen motility in conscious goats and sheep

Loperamide inhibited the frequency and amplitude of cyclical contractions of the rumen in conscious goats (100 micrograms/kg, i.v. and sheep (250 micrograms/kg, i.v.). In goats, the inhibitory effect of loperamide could be prevented by pretreatment with the opiate antagonist naltrexone (greater than or equal to 12.5 micrograms/kg, i.v.) but not by pretreatment with the dopaminergic antagonist domperidone (500 micrograms/kg, i.v.). Intracerebroventricular administration of 1 microgram/kg loperamide in goats significantly depressed ruminal contraction frequency, whereas intravenous administration of 10 micrograms/kg loperamide did not affect cyclical motility. Administered via the carotid artery, loperamide (4 micrograms/kg) depressed both frequency and amplitude of cyclical contractions of reticulum and rumen, whereas the same dose was ineffective via the coeliac artery. In vitro, loperamide (10 nM-100 microM) had no influence on spontaneous activity or tone of the reticular longitudinal muscle strips. It is concluded that loperamide inhibits cyclical ruminal contractions through a central opioid pathway.     

Vagal reflex inhibition of motility in the abomasal body of sheep by antral and duodenal tension receptors

Vagally-mediated regulation of motility in the abomasal body by duodenal and abomasal antral motility was demonstrated in acutely prepared anaesthetized sheep. The enteric plexuses between the abomasal body, antrum and duodenum were interrupted by transection. Antral contractions were more effective than duodenal contractions at causing inhibition of the abomasal body, and antral isometric conditions were more effective than antral isotonic conditions. Inhibition of motility in the abomasal body was reduced by unilateral cervical vagotomy, was abolished by bilateral cervical vagotomy, and was reversibly inhibited by cervical vagus cold block. The demonstration of vagal pathways in abomaso-abomasal reflexes confirms a functional homology of the mechanisms in the ruminant and animals with simple forms of stomach.Abbreviations b-t balloon-tipped - EMG electromyography - NANC non-adrenergic, non-cholinergic - o-t open-tipped     

Effect of anticholinergics (atropine, glycopyrrolate) and prokinetics (metoclopramide, cisapride) on gastric motility in beagles and labrador retrievers

The effect of atropine, glycopyrrolate, metoclopramide and cisapride on the antral motility was investigated in eight dogs (four Beagles and four Labradors) using passive telemetry. Both anticholinergics induced a pronounced and lasting reduction of the intensity and frequency of the contractions. A definite dose-related inhibition of the antral motility was seen in Beagles, similar for both active substances. Low doses of atropine (0.02 mg/kg BW i.m.) and glycopyrrolate (0.005 mg/kg BW i.m.) completely inhibited the gastric motility for at least 30 min, whereas higher doses (0.04 or 0.01 mg/kg BW) caused a cessation of activity for more than 3 h. In Labradors, the effects of both active substances were not so dose related and the effect of glycopyrrolate lasted at least 6 h, whereas the effect of atropine gradually decreased after 3 h. A distinct breed difference regarding the effect of the two prokinetics on the antral motility was also observed. In Beagles, the prokinetics, at a low dose (metoclopramide 0.3 mg/kg BW, cisapride 0.2 mg/kg BW), resulted in a significant increase in the amplitude integral. Higher doses (metoclopramide 0.6 mg/kg BW, cisapride 0.5 mg/kg BW) also increased the integrals of the pressure profiles, but significantly less than with the lower doses. In Labradors, both medications, mainly at higher doses, resulted in an increase of the contraction amplitudes. The low dose had no (cisapride) or only a transient effect (metoclopramide). The frequency of the antral contractions was not at all influenced by cisapride, and only in Beagles metoclopramide resulted in a dose-related increase. It is not clear if the different results in Labradors and Beagles are because of breed or body weight.     

Depression of reticulo-ruminal motor functions through the stimulation of 012-adrenoceptors

Inhibition of the cyclical contractions of the reticulum and the rumen by detomidine (10-40 micrograms/kg, i.v.), xylazine (20-80 micrograms/kg, i.v.) and clonidine (2.5-10 micrograms/kg, i.v.) were compared in sheep and cattle housed individually in box stalls. Two alpha 2-adrenergic receptor blocking agents, tolazoline and yohimbine, were administered intravenously for prevention (0.1-0.4 mg/kg) or reversal (0.4-1.2 mg/kg) of these effects. Continuous recording of the reticuloruminal contractions and measurement of the volume of ruminal gas eliminated through the upper respiratory tract indicated that the three alpha 2-agonists inhibited the primary ruminal contractions associated with the reticular contractions. The occurrence of secondary ruminal contractions was also blocked in sheep, but only suppressed in cattle. The inhibition of reticulo-ruminal contractions was prevented or reversed competitively by the two alpha 2-blocking agents, suggesting an alpha 2-adrenoceptor mediation of the inhibition of cyclical motor activity of the reticulo-rumen. In contrast with tolazoline, yohimbine was unable to alleviate the accumulation of gas resulting from inhibition of the secondary ruminal contractions.     

Motility of the large intestine and flow of digesta in pigs

The motor function of the large intestine of pigs is incompletely understood. Here the ileo-caecal-colonic motility is investigated by means of chronically implanted extraluminal strain gauge transducers and simultaneous videofluoroscopy in six pigs. Motility parameters were evaluated by computer and manually. The dominant feature of the ileal motility were aborally propagating giant contractions (velocity: 3.9 (0.7) cm sec(-1)) occurring at intervals of 7-12 minutes. They pushed the ileal digesta into the caecum. Despite a fed-state, migrating motor complexes occurred at intervals of 131.5 (8.1) minutes consisting of repetitive peristaltic waves. The motility of the caecum showed clustered contractions representing haustral movements. Transfer of caecal digesta and gas into the colon was caused by peristaltic contractions. The motility of the proximal colon was characterised by long peristaltic waves resulting in a rapid aboral transport of gas and a slow aboral flow of digesta. The propagation velocities along the centripetal and centrifugal loops of the colonic coil were 2.8 (0.6) and 5.7 (0.8) cm sec(-1), respectively. About half of the colonic waves were coordinated with the ileal giant contractions and the caecal peristaltic waves. The contraction parameters showed pronounced differences between the ileum and large intestine. The contraction rise time of the caecal and colonic contractions was about twice that of the ileal contractions (5.1 (0.2) and 4.4 (0.6) seconds versus 2.2 (0.1) seconds). Consequently, the maximal frequencies of the caecal and colonic contractions were about half compared with the ileal contractions (5.3 (0.4) and 6.1 (0.1) contractions min(-1) versus 11.8 (0.3) contractions min(-1)). Results show that the contractile patterns and motor functions of the individual intestinal segments differ markedly.     

Reference Values and Repeatability of Transabdominal Ultrasonographic Gastrointestinal Tract Thickness and Motility in Healthy Donkeys (Equus asinus)

The present study aimed to provide reference ranges for the wall thickness and motility pattern of the gastrointestinal tract from a sample of donkeys (Equus asinus) population using B-mode ultrasonography. In the present study, 30 clinically healthy donkeys (Equus asinus) (15 males and 15 females), aged 2–20 year old and weighed 100–280 kg were randomly selected for B-mode ultrasonographic scanning of the abdomen. The wall thickness of the stomach, duodenum, jejunum, left colon, right colon, and cecum was assessed. Moreover, the motility pattern of the duodenum, jejunum, left colon, right colon, and cecum was evaluated over a period of 3 minutes. Abdominal ultrasonographic scanning of the gastrointestinal tract of healthy donkeys explored that the stomach, duodenum, jejunum, left colon, right colon, and cecum could be visualized easily. The wall thickness of the stomach, duodenum, jejunum, left colon, right colon, and cecum was 7.0 ± 0.9 mm, 3.3 ± 1.0 mm, 5.4 ± 0.6 mm, 5.1 ± 0.5 mm, 5.4 ± 0.5 mm, and 5.4 ± 0.6 mm, respectively. The thickest part of the gastrointestinal tract is the stomach, whereas the thinnest part is the duodenum. The motility pattern of the duodenum, jejunum, left colon, right colon, and cecum was 7.7 ± 1.3 contractions/3 minutes, 6.9 ± 1.1 contractions/3 minutes, 4.1 ± 1.2 contractions/3 minutes, 5.5 ± 1.3 contractions/3 minutes, and 4.0 ± 0.8 contractions/3 minutes, respectively. Both the duodenum and jejunum contractions were significantly higher than that of the left colon, right colon, and cecum. This is the first study reporting the reference values for both the wall thickness and motility pattern of the gastrointestinal tract in healthy donkeys (Equus asinus) in Egypt. Good knowledge of these standard and reference values of the wall thickness and motility pattern of gastrointestinal tract structures represents a step in the early diagnosis of the gastrointestinal disorders, including colic in such animal species.     

Colonic motor responses in the pony: relevance of colonic stimulation by opiate antagonists

The electrical and mechanical activity of the digestive tract and its response to the administration of opiate agonists and antagonists was assessed from electrodes and strain gauges chronically implanted on the jejunum and the cecocolonic segments in 3 ponies given a diet of hay and concentrates. Before the drugs were given, 10 to 17 migrating myoelectric complexes/day were recorded on the small intestine, and a rhythmic motor activity (base line) was observed on the proximal portion of the colon at the rate of 3.5 to 6.6/hour. Propagated contractions from the proximal to the distal portion of the colon occurred at the rate of 1.5 to 2.3/hour. Each pony was used as its own control and was given morphine (0.5 or 1 mg/kg of body weight, IV) or fentanyl (0.01 or 0.05 mg, IV) at weekly intervals. After an early phase of inhibition of the overall activity that lasted from 0.5 to 3 hours, depending on the dose, the resting muscle tone of the colonic activity was increased for a dose-dependent period. Propagated contractions only reappeared at the end of this 2nd phase. The opiate antagonist naloxone (0.5 mg/kg, IV) elicited a marked propulsive activity on the left replicated colonic segment, characterized by an increase in the number of propagated contractions. The N-methyl-quaternary analog of naloxone (methylnaloxone, which presumably entails selective action at opiate receptors outside the CNS) was also effective, indicating peripheral effects at the dosage level used (0.5 mg/kg, IV). Seemingly, an inhibitory opioid system exists in the control of colonic motor function in ponies and the possible usefulness of opiate antagonists to relieve hypomotility resulting in colonic impaction and constipation.     

Central and local actions of opioids upon reticulo-ruminal motility in sheep

The effects of opioids and naloxone on cyclical forestomach motility were determined in anaesthetized and conscious sheep. To assess central or peripheral opioid actions, differential routes of administration were used. Possible dynamic effects along the innervating vagovagal reflex arc were investigated electrophysiologically at the cervical level of the vagus nerve. Further, direct influences on the smooth muscle were evaluated in vitro on isolated longitudinal reticular strips. Additionally, the effects of some spasmogenic agents were studied for comparative purposes. In anaesthetized sheep, opioids depressed in an identical manner both the amplitude of spontaneous cyclical contractions and contractions evoked by electrical stimulation of the distal end of the cut cervical vagus. In conscious sheep, low doses of normorphine and loperamide inhibited frequency and amplitude centrally (20 micrograms/kg and 4 micrograms/kg via carotid artery respectively), whereas locally higher dose levels (200 micrograms/kg and 10 micrograms/kg via coeliac artery respectively) affected only the amplitude of cyclical contractions. Furthermore the opioid peptides Leu-, Met-enkephalin and [D-Ala2-Met5]-enkephalinamide preferentially depressed the amplitude of cyclical motility most efficiently if administrated via the coeliac artery. These results indicate the presence both of a central opioid action depressing frequency and amplitude and of a local opioid action depressing only the amplitude of cyclical reticulo-ruminal motility. Opioids did not alter the resting discharge of afferent tension units and similarly failed to modulate tone of reticular strips in vitro, suggesting that the opioids act locally on the intramural neuronal plexus, possibly by diminishing the output of excitatory transmitter. Whether substance P could play a role as a vagal excitatory transmitter besides the classically implicated acetylcholine has been discussed. The central opioid mechanism is probably not situated within the gastric centres but elsewhere in the brain. Naloxone (greater than or equal to 100 micrograms/kg, jugular vein) stimulated the frequency of cyclical ruminal motility only in well-defined experimental conditions, probably via a central mechanism.     

Ultrasonography of the reticulum in 30 healthy Saanen goats

Background

The reticulum plays a crucial role in the ruminant digestive tract because the primary cycle of rumen motility always starts with a reticular contraction. In contrast to cattle, there are only few results on the ultrasonographic examination of the reticulum in goats. Therefore, it was the goal of the present study, to describe the results of ultrasonography of the reticulum of 30 healthy Saanen goats.

Methods

Ultrasonography was carried out on standing, non-sedated animals using a 5.0 MHz linear transducer. The shape, contour and motility of the reticulum were investigated. A nine-minute video recording of the reticulum was made for each goat and the frequency, duration and amplitude of reticular contractions were calculated as described for cattle.

Results

The reticulum appeared as a crescent-shaped structure with a smooth contour located immediately adjacent to the diaphragm. 0.8 to 2.1 (1.41 ± 0.31) reticular contractions were seen per minute. In all goats, biphasic reticular contractions were observed. 90% of the goats also had monophasic reticular contractions, and two had triphasic contractions. During the nine-minute observation periods, there were 0 to 6 monophasic reticular contractions and 6 to 15 biphasic contractions per goat. The duration of the biphasic contractions was 6.56 ± 0.74 s, which was significantly longer than the monophasic contractions at 4.31 ± 0.81 s. The average interval between two reticular contractions was 45.06 ± 12.57 s.

Conclusion

Ultrasonography of the reticulum in goats is a valuable tool to characterise the appearance and motility of this organ. In addition to the biphasic motility pattern seen in cattle the reticular motility of goats is characterized by monophasic reticular contractions. The results of the present study are an important contribution for better understanding of the reticular motility in goats.     

Nonsteroidal anti-inflammatory drugs induce hypermotilinemia and disturbance of interdigestive migrating contractions in instrumented dogs

Nonsteroidal anti-inflammatory drugs (NSAIDs) induce gastric ulcers due to inhibition of prostaglandin production. Prostaglandins have an influence on physiological gastrointestinal motility, but the relationships between NSAID-induced gastric ulcer, gastrointestinal motility and motilin are unknown. Fifteen dogs were allocated randomly to three groups in which either gelatin, meloxicam or indomethacin was administered. Fecal occult blood and gastrointestinal motility were monitored continuously for 6 days. In addition, analyses of the plasma motilin concentration, gastrointestinal endoscopy and gastric emptying, and detection of motilin cells were performed. Gastrointestinal motility was disturbed in the indomethacin group, presenting as disappearance of interdigestive migrating contractions (IMCs) 3 days before gastric ulcers were detected. Delayed gastric emptying and hypermotilinemia were observed significantly more often in the indomethacin group compared with the other groups. Motilin cell-crypt/villi ratio in the indomethacin group significantly decreased in the duodenum and jejunum, compared with the other groups. No significant changes in any tests were observed in the meloxicam group, when compared with the gelatin group. These findings suggest that the disturbance of IMCs caused by hypermotilinemia, with changes in motilin cell distribution, and delayed gastric emptying induced by indomethacin may contribute to the development of gastric ulcers.     

Role of nitrergic nerves in the regulation of motility of the omasum and abomasum in healthy sheep <Emphasis Type="Italic">(Ovis aries)</Emphasis>

We examined the physiological role of nitrergic nerves in the regulation of omasal and abomasal motility in conscious healthy sheep and omasal muscle specimens. Nitric oxide (NO)-donor, S-nitroso-acethyl-dl-penicillamine (SNAP, 3-30 nmol/kg per min, i.v.) significantly inhibited omasal electromyographic (EMG) activity, whereas it did not alter EMG activity in the abomasal antrum. However, NO synthase inhibitor, Nomega-nitro-l-arginine-methyl ester (L-NAME, 0.3-3.0 micromol/kg per min, i.v.) did not alter EMG activity of the omasum and abomasum. In the in vitro experiments, SNAP application (6-200 micromol/l) significantly inhibited bethanechol (10 micromol/l)-induced contraction of longitudinal and circular muscles of the omasum. L-NAME application (0.03-3.0 mmol/l) enhanced electric field stimulation-induced contractions of the circular muscles. The results suggest that the omasal muscles are responsive to exogenous NO and that nitrergic nerves innervate the circular muscle layer of the omasum, however, nitrergic nerves are not or scarcely involved the physiological regulation of omasal and possibly abomasal motility in healthy sheep.     

Effect of romifidine on gastrointestinal motility, assessed by transrectal ultrasonography.

A technique of transrectal ultrasonography was developed to investigate the effects of romifidine 80 and 120 microg/kg bwt on intestinal motility in the horse. Motility of the small intestine, caecum and left ventral colon were assessed following injection of romifidine and a saline control, using a blinded, cross-over study design in 6 horses. Measurements were taken at 15, 30, 60, 120, 180 and 240 min after drug administration. There was a slight nonsignificant decrease in motility in the control group over the 4 h study period. Both doses of romifidine produced a marked decrease in gastrointestinal motility and were associated with the presence of reduced (nonpropulsive) contractions. Transrectal ultrasonography proved suitable for monitoring changes in the type and frequency of intestinal motility in the horse.     

Gallbladder motility in sheep: effects of cholecystokinin and related peptides

Gallbladder motility was recorded as tonic and small amplitude (rhythmic) contractions in conscious sheep fitted with miniaturized strain-gauge force transducers located in the corpus and fundus. Nichrome wire electrodes were chronically implanted in the gastroduodenal area. Both tonic and superimposed rhythmic gallbladder contractions were increased during feeding. They decreased during the periodic phases of antroduodenal quiescence. The excitatory effects on gallbladder and antroduodenal motility were mimicked by pilocarpine and blocked by atropine. Cholecystokinin (CCK-OP) and caerulein elicited motor responses of the gallbladder in a dose-related manner without antroduodenal stimulation. In contrast, pentagastrin induced gallbladder motor responses with concomitant stimulation of the antroduodenal area. The results suggest that feeding may act to trigger gallbladder motor activity through a mechanism related to the increased antroduodenal activity. Direct effects of CCK-OP and caerulein confirm that gallbladder motor function is also mediated through specific receptor sites.     

Motility of the rumen and abomasum during hypocalcaemia.

The relationship between plasma calcium level and rumen motility in cows and sheep and abomasal motility in cows was investigated by inducing hypocalcaemia in seven cows and five sheep by the infusion of Na2 EDTA over a period of approximately two hours. Rates and amplitudes of rumen and abomasal contractions were markedly reduced by the reduction of plasma calcium level to approximately 50% of normal. There were significant positive linear relationships (P less than 0.05) between rate and amplitude of rumen contractions in both sheep and cows over a plasma calcium range of 1-3 mmol/L. There was also a significant linear relationship (P less than 0.05) between plasma calcium and abomasal rate of contraction over the same range in cows, but the relationship with amplitude of abomasal contraction was not quite significant (P less than 0.1 greater than 0.05).     

Central and peripheral β-adrenergic influences on reticulo-rumen and upper-gut myoelectrical activity in sheep

The effects of intravenous (i.v.) and intracerebroventricular (i.c.v.) administration of beta-adrenoceptor agonists were evaluated on the reticulo-rumen and upper-gut myoelectrical activity in six ewes chronically fitted with intraparietal electrodes and a cannula in a lateral ventricle of the brain. Intravenous infusion of the beta 1 agonist dobutamine (30 micrograms/kg/min for 15 min) reduced the frequency of reticulo-ruminal and abomasal contractions and stimulated duodeno-jejunal motility, inducing a Phase III on the jejunum. These effects were reproduced by i.c.v. dobutamine at a dose of 10 micrograms/kg. Intravenous infusion of the beta 2 agonist ritodrine (15 micrograms/kg/min for 15 min) selectively inhibited antral and duodenal motility. Ritodrine i.c.v. (15 micrograms/kg) did not affect forestomach or gastrointestinal motility. The mixed beta 1, beta 2 agonist isoprenaline infused i.v. (0.6 micrograms/kg/min for 15 min) reproduced the effects of i.v. dobutamine, except at the antro-duodenal level which was strongly inhibited. The effects of i.v. dobutamine were antagonized by i.v. or i.c.v. acebutolol, a specific beta 1 antagonist. The effects of i.v. ritodrine were blocked by i.v. but not i.c.v. administration of propranolol, a mixed beta 1, beta 2 antagonist. These data indicate that the stimulation of central beta 1 adrenoceptors inhibits forestomach and antral motility and stimulates duodeno-jejunal motility. Stimulation of peripheral beta 2 adrenoceptors selectively inhibits duodeno-jejunal motility.     

Ultrasonographic evaluation of reticular motility in cows after administration of atropine,scopolamine and xylazine

The goal of this study was to evaluate the effect of various dosages and routes of administration of atropine, scopolamine and xylazine on reticular motility in cows. Groups of five cows received atropine, scopolamine or xylazine at dosages varying from 0.01 to 0.20 mg/kg. The drugs were administered intramuscularly and intravenously; atropine was also given subcutaneously. A total of 17 trials, each using five cows, were carried out. Reticular motility was assessed for 3 min immediately prior to the administration of a drug and for 21 min after administration, and the latter period was divided into seven 3-min intervals. The motility was further assessed during 3-min periods every 10 min starting 28 min and ending 141 min after administration of a drug. During each 3-min interval, the number of reticular contractions or the occurrence of reticular atony was determined. Onset and duration of reticular atony were assessed. All three drugs inhibited reticular motility but onset varied with route of administration and dosage. As expected, the onset of reticular atony occurred most rapidly after intravenous administration of each drug, followed by intramuscular and subcutaneous administration. Reticular atony occurred 0-3.0 min after the intravenous administration of each drug and at all dosages except the lowest dosage of atropine. Atony lasted for 3-111 min. Reticular atony occurred 3-18 min and 9-15 min after intramuscular and subcutaneous administration, respectively. It lasted 32-108 min and 39-122 min for the intramuscular and subcutaneous routes, respectively. For each drug, higher dosages resulted in a more rapid onset and longer duration of reticular atony than did lower dosages. This study demonstrated that administration of atropine, scopolamine and xylazine results in reticular atony. Whether this has clinical relevance requires further investigation.     

Effect of orally administered cimetidine and ranitidine on abomasal luminal pH in clinically normal milk-fed calves

OBJECTIVE: To characterize the change of pH in the abomasal lumen throughout a 24-hour period, to determine whether pH of the abomasal body differs from pH of the pyloric antrum, and to determine whether oral administration of cimetidine and ranitidine alters pH of the abomasal lumen in milk-fed calves. ANIMALS: 5 male dairy calves (4 Holsteins-Friesian, 1 Ayrshire), 5 to 15 days old. PROCEDURE: Cannulas were surgically positioned in the abomasal body and pyloric antrum of each calf. Calves received the following treatments in a randomized crossover design: milk replacer (60 ml/kg of body weight, q 12 h [untreated control calves]), milk replacer and cimetidine (50 or 100 mg/kg, q 8 h), or milk replacer and ranitidine (10 or 50 mg/kg, q 8 h). The pH of the abomasal body and pyloric antrum was measured for 24 hours, using miniature glass pH electrodes. RESULTS: Suckling of milk replacer immediately increased abomasal luminal pH from 1.4 to 6.0, followed by a gradual decrease to preprandial values by 6 hours. Preprandial and postprandial pH values were not significantly different between the abomasal body and pyloric antrum, indicating lack of pH compartmentalization in the abomasum of milk-fed calves. Administration of cimetidine and ranitidine caused a significant dose-dependent increase in mean 24-hour abomasal luminal pH. CONCLUSIONS AND CLINICAL RELEVANCE: Abomasal acid secretion in milk-fed calves is mediated in part by histamine type-2 receptors. Cimetidine and ranitidine may be efficacious in the treatment of abomasal ulcers in milk-fed calves.     

Effects of experimental duodenal occlusion on electrical activity of the proximal duodenum in cattle

An electromyographic study of the proximal duodenum in cattle is presented. Changes of motility patterns were studied after induced mechanical obstruction of the descending duodenum in five healthy cows. Special attention was paid to the ratio of antegrade and retrograde motility. Induced duodenal obstruction of which the duration was at most 48 hours, resulted in abrupt disorganisation of the migrating myoelectric complexes; the phases of regular spiking activity disappeared completely or reappeared in a disorganised pattern, and the phases of irregular spiking activity consisted of repetitive groups of spike bursts with prolonged duration and increased propagation velocity. Retrograde peristaltic contractions in the proximal duodenum were observed. Relief of obstruction resulted in a rapid reorganisation of the cyclic pattern of the migrating myoelectric complexes, which indicates normalisation of intestinal activity.     

Assessment of the effects of erythromycin, neostigmine, and metoclopramide on abomasal motility and emptying rate in calves

OBJECTIVE: To determine and compare the effects of erythromycin, neostigmine, and metoclopramide on abomasal motility and emptying rate in suckling calves. ANIMALS: 6 male Holstein calves (15 to 40 days of age). PROCEDURE: Calves were monitored for 1 hour before being fed milk replacer (60 mL/kg; time, 0 minutes) and then were monitored for another 3 hours. Calves received 6 treatments in randomized order: erythromycin (8.8 mg/kg, IM) at -30 minutes; low-dose erythromycin (0.88 mg/kg, IM) at -30 minutes; erythromycin (8.8 mg/kg, IM) at -30 minutes and neostigmine (0.02 mg/kg, SC) at -30 and 90 minutes; neostigmine (0.02 mg/kg, SC) at -30 and 90 minutes; metoclopramide (0.1 mg/kg, IM) at-30 and 90 minutes; and placebo (2 mL of saline [0.9% NaCl] solution, SC) at -30 minutes. Abomasal volume was calculated from ultrasonographic measurements of abomasal width, length, and height. Abomasal motility and emptying rate were assessed by measuring luminal pressure and change in abomasal volume over time. RESULTS: Administration of erythromycin (8.8 mg/kg) increased the frequency of abomasal luminal pressure waves and the mean abomasal luminal pressure and decreased the half-time of abomasal emptying by 37%. Administration of metoclopramide, neostigmine, and low-dose erythromycin (0.88 mg/kg) did not alter abomasal motility, mean luminal pressure, or emptying rate. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that administration of erythromycin at the labeled antimicrobial dose (8.8 mg/kg, IM) exerted an immediate, marked prokinetic effect in healthy suckling calves, whereas administration of metoclopramide or neostigmine did not alter abomasal motility or emptying rate.