DUODENAL ULTRASONOGRAPHY IN THE NORMAL ADULT HORSE

Ultrasonographic Assessment of Small Intestinal Motility Following Hyoscine Butylbromide Administration in Horses: A Pilot Study

Horses commonly receive hyoscine butylbromide (HB) prior to hospital admission for colic. This could alter the appearance of the small intestine (SI) on ultrasound scan and affect clinical decision making. The aim of this study was to assess the impact of HB on ultrasonographically assessed SI motility and heart rate. Six horses hospitalised for medical colic with no significant abnormalities on baseline abdominal ultrasound examination were included. Ultrasound was performed in three locations (right inguinal, left inguinal and hepatoduodenal window) before and at 1, 5, 15, 30, 45, 60, 90, and 120 minutes after intravenous injection of 0.3 mg/kg HB. Three blinded reviewers assessed SI motility using a subjective grading scale from 1 to 4, one being normal motility and four being no motility. Moderate interindividual and interobserver variability was observed, but none of the included horses developed dilated turgid loops of SI. Hyoscine butylbromide did not significantly reduce SI motility grade in any location (P = .60 left inguinal, P = .16 right inguinal, P = .09 duodenum). Heart rate (mean ± SD) was 33 ± 3 prior to HB injection and peaked at 71.3 ± 9 one-minute postinjection. Heart rate was significantly increased until 45 minutes (48 ± 9) after HB administration (P = .04). The appearance of dilated turgid SI loops common with strangulating intestinal lesions did not appear to develop following HB administration. Hyoscine butylbromide administered shortly before abdominal ultrasound examination would not be expected to affect clinical decision making in horses without small intestinal disease.

Ex vivo ultrasonographic and histological morphometry of small intestinal wall layers in horses

Ultrasonographic morphometry of wall layers is commonly used in veterinary patients with suspected small intestinal disease, however published studies comparing this method with histopathology in horses are limited. This prospective, methods comparison study compared the qualitative and quantitative characteristics of small intestinal wall layers using ex vivo high‐frequency ultrasound versus histopathology in a sample of 16 horses. Transverse section images of duodenum, distal jejunum, and ileum were acquired with a high‐frequency linear transducer (7–15 MHz). Transverse histological cryosections were obtained at the same level. Appearance and measurements of the intestinal wall layers were assessed on the ultrasonographic and histological images. High‐frequency scanning with the probe in close contact with the serosal surface of the equine intestinal wall allowed a clear and detailed definition of wall layers. A hyperechoic line was consistently detected within the tunica muscularis in all the intestinal tracts, corresponding histologically to the interface between its longitudinal and circular muscle layers. The overall trend of the values for wall layers thickness was comparable between ex vivo ultrasonography and histology. However, a poor agreement was found between the two methods for all layers. The ultrasonographic measurements were thicker compared to histological measurements, with the exception of the total wall and the muscular layer thicknesses. These layers were thinner on ultrasonography in the duodenum and in all the intestinal segments, respectively. Findings from the current study can be used as background for future ultrasonographic investigations of small intestinal diseases in horses.

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.

Gastrointestinal effects of general anaesthesia in horses undergoing non abdominal surgery: focus on the clinical parameters and ultrasonographic images

The ultrasonographic images of the gastrointestinal tract in horses can be influenced by fasting and sedation but the proper effect of general anaesthesia (GA) on them has not been determined yet. This study aimed to evaluate the effects of GA on ultrasonographic images of the gastrointestinal tract in horses and to compare these effects with a clinical evaluation. Twenty horses undergoing non-abdominal surgeries were evaluated by ultrasonography before and 4 times within 24 h after GA. Each ultrasonographic exam focused on the stomach, the duodenum and on 5 locations on the jejunum. The four-quadrant auscultation and the postoperative faecal output were also recorded. Pre and post anaesthetic values were compared using linear mixed effects models. None of the horses presented colic signs or reduced faecal output. During the first 2 post anaesthetic evaluations, the gut sounds were significantly decreased and, when taking all jejunal locations together, the jejunal diameter and visualisation frequency significantly increased. No intestinal loop appeared thickened and most of their diameters remained within the normal range. Our results suggest that the effects of GA on the ultrasonographic images of the small intestine are mild and of short duration and can therefore be differentiated from a pathological process.

Techniques and Accuracy of Abdominal Ultrasound in Gastrointestinal Diseases of Horses and Foals

Diagnostic ultrasonography has been used as a test to determine the presence or absence of gastrointestinal disease in horses and foals. General techniques and anatomic landmarks are reviewed. Many clinical reports that have included diagnostic ultrasound as part of their diagnostic process and accuracy studies are necessary to determine the usefulness of diagnostic ultrasound in clinical practice.

Correlation between capillary oxygen saturation and small intestinal wall thickness in the equine colic patient

The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4 mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness.

Ultrasound of the equine acute abdomen

Abdominal ultrasound is an invaluable aid in the evaluation of the colic patient but can be heavily influenced by patient preparation, individual horse-to-horse variation, availability of ultrasound transducers, technique, experience level of the examiner, and complexity of the abdominal disorder. This article describes ultrasonographic anatomy of the normal equine abdomen and technique for examination of the equine colic patient. Common abnormalities of the stomach, small intestine, large intestine, and peritoneal cavity are described along with other abnormalities that may be discovered with abdominal ultrasonography of the colic patient, such as masses, urolithiasis, cholelithiasis, and thoracic or cardiac lesions.

Comparison of glycopyrrolate and atropine in ameliorating the adverse effects of imidocarb dipropionate in horses

REASONS FOR PERFORMING STUDY

Imidocarb, an effective treatment for piroplasmosis, may cause colic and diarrhoea in horses. Atropine and glycopyrrolate are anticholinergics that could reduce the adverse effects of imidocarb. However, atropine and glycopyrrolate inhibit gastrointestinal motility, potentially causing ileus and colic.

OBJECTIVES

To compare glycopyrrolate and atropine in ameliorating the adverse effects of imidocarb dipropionate in horses and to determine the effect of combinations of these drugs on the gastrointestinal tract.

METHODS

A blinded, randomised, crossover study was performed in 8 healthy horses. Each horse received 0.9% saline i.m and i.v. (CON), and imidocarb 2.4 mg/kg bwt i.m. with one of 3 treatments i.v.: 0.9% saline (IMI), atropine 0.02 mg/kg bwt (IMATROP) and glycopyrrolate 0.0025 mg/kg bwt (IMGLYCO). Clinical data, gastrointestinal motility via borborygmi and frequency of contractions in the duodenum, caecum and right dorsal colon assessed with transabdominal ultrasound, and faecal data were measured.

RESULTS

After imidocarb/saline treatment colic and diarrhoea were noted in 3 and 4 horses, respectively, faecal production and defaecation were increased for 3 h and faecal water percentage for 6 h. Colic was noted after atropine treatment in 4 horses, borborygmi and frequency of right dorsal colon contractions were significantly decreased for 2 h 15 min, and faecal production was not significantly different from CON. After glycopyrrolate treatment, colic was seen in one horse, frequency of intestinal contractions and faecal data were not significantly different from CON, and borborygmi was significantly decreased from CON at 1 h 15 min.

CONCLUSIONS

Results of this study suggest that glycopyrrolate is superior to atropine in ameliorating the adverse effects of imidocarb.

POTENTIAL RELEVANCE

Glycopyrrolate could be administered with imidocarb in horses with piroplasmosis to reduce the adverse effects of imidocarb.