Sonographic Evaluation of the Adult Abdomen

Approach to Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) in the horse encompasses a group of infiltrative gastrointestinal disorders resulting in malabsorption, maldigestion, weight loss, colic, and sometimes diarrhea. The type of IBD can be classified as granulomatous, lymphocytic-plasmacytic, or eosinophilic enterocolitis. The diagnosis of IBD in equids is based on consistent clinical signs and clinicopathologic findings in conjunction with confirmatory histopathology from a gastrointestinal biopsy. Treatment usually consists of a combination of immunosuppressive medications, anthelmintics, and dietary modifications. The prognosis of IBD in horses is variable and dependent on the horse's response to treatment; however, horses can show improvement or resolution of clinical signs.

[Ultrasonographic findings of the stomach in warmblood horses at different filling states]

SUBJECT AND AIM

The aim of the study was to clarify to what extent the sonographic representation of the stomach changes depending on its filling state.

MATERIAL AND METHODS

In a prospective controlled study, warmblood horses presented for gastroscopy were assessed sonographically. The examinations took place when the horses were fed normally (measurement 1), after 12 hours of food deprivation (measurement 2), after insufflation of air during gastroscopy (measurement 3) and after removal of air from the stomach at the end of the gastroscopy (measurement 4). The following objective parameters were recorded: Number of intercostal spaces (craniocaudal extension) and determination in which intercostal spaces the stomach could be visualized sonographically, maximum dorsal extension of the stomach, distance between skin and stomach wall.

RESULTS

The median number of intercostal spaces in which the stomach could be visualized sonographically was 7.5 (IQR 3.75), 1.0 (IQR 1.0), 7.0 (IQR 2.0) and 2.0 (IQR 1.0) for measurements 1, 2, 3 (n=32) and 4 (n=15), respectively. The differences were significant between measurements 1 and 2 and between measurements 2 and 3. There was no significant difference between measurements 1 and 3. After 12 hours of food deprivation, the stomach size measured by the number of intercostal spaces visualizing the stomach was reduced by 75%. The maximum dorsal expansion of the stomach for measurements 1, 2, 3 (n=32) and 4 (n=15) was a median of 38 cm (IQR 15.25), 13 cm (IQR 6.75), 43 cm (IQR 7.00) and 21 cm (IQR 8.00), respectively. The differences were significant between measurements 1 and 2 and between 2 and 3. Concerning the distance between skin and stomach wall, the following medians were determined for measurements 1, 2, 3 (n=32) and 4 (n=15): 5.8 cm (IQR 2.27), 4.05 cm (IQR 3.05), 4.8 cm (IQR 1.48) and 5.9 cm (IQR 2.90). The only statistically significant difference was observed between measurements 1 and 3.

CONCLUSIONS AND CLINICAL RELEVANCE

The sonographic appearance of the stomach changes according to the state of filling. Parameters that are readily determined sonographically are the craniocaudal and maximum dorsal extension as well as the distance between the skin and the stomach wall.

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.

Ultrasonographic visualisation of the mesenteric vasculature in horses with large colon colic

BACKGROUND

Ultrasonographic visualisation of the mesenteric vasculature of the large colon (LC) from the right side of the abdomen in cases of displacement and volvulus has been described. However, the LC can move freely within the abdomen and its mesentery can potentially contact both sides of the abdominal wall.

METHODS

Thirty-four horses presented with LC-related colic that had visible LC mesenteric vasculature visible on abdominal ultrasound were included. A control group was made including horses with confirmed small intestinal-related colic. The objective of this study was to evaluate the visibility of LC mesenteric vasculature with transabdominal ultrasonography in horses with LC-related colic and to determine its diagnostic value.

RESULTS

The LC mesenteric vasculature was identified on the right side of the abdomen in 16/34 horses with right dorsal displacement of the LC (RDDLC), 180° LC volvulus (LCV), 540° LCV or LC impaction. On the left side of the abdomen, LC mesenteric vessels were identified in 17/34 horses with left dorsal displacement of the LC (LDDLC), 180° LCV or RDDLC. Vessels were visualised on both sides in one horse with a 180° LCV. Presence of LC mesenteric vasculature in the dorsal aspect on the left side of the abdomen was significantly associated with LDDLC.

CONCLUSION

LC mesenteric vasculature can be visualised on transabdominal ultrasound from either side of the abdomen in horses with different forms of LC-related colic.

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.

Right dorsal colon ultrasonography in normal adult ponies and miniature horses

The aim of this study was to determine the normal location, wall thickness and motility of the right dorsal colon in adult ponies and miniature horses. The abdominal ultrasonography examination was performed in a study group consisting of 23 ponies and miniature horses and in a control group comprising ten Thoroughbred horses. The procedure was performed in unsedated standing animals. The location and the thickness of the right dorsal colonic wall was examined on the right side of the abdomen between the 10^th and the 14^th intercostal space. The contractility was recorded in the 12^th intercostal space. A comparative analysis between the study group and control group was carried out using the Student’s t-test. Pearson’s linear correlation coefficient was used to calculate the correlation between the thickness of the colonic wall as well as the number of peristaltic movements and age, wither height and body mass of the animals. The right dorsal colon was identified in all the horses in the 12^th intercostal space. In all the intercostal spaces the mean ± standard deviation (SD) wall thickness of the right dorsal colon was 0.27 ± 0.03 cm in the horses from the study group and 0.37 ± 0.03 cm in the control horses. The mean number of peristaltic contractions was 4.05 ± 1.07 per minute in the animals from the study group and 1.7 ± 0.46 contractions per minute in the control group. The values of the ultrasonographic wall thickness and peristaltic motility in small breed horses in the present study were different from the values obtained for large breed horses. The study also found that the right dorsal colon in small breed horses is physiologically located in the 12^th intercostal space. This suggests that different reference values should be used in small horse breeds when performing an ultrasound examination.

Medical and surgical management of an intra-abdominal abscess of hepatic origin in a horse

CASE DESCRIPTION

A 4-year-old Arabian-cross mare was examined because of a 48-hour history of pyrexia, lethargy, and signs of abdominal discomfort.

CLINICAL FINDINGS

On initial evaluation, the horse was in good body condition, but febrile, tachycardic, tachypneic, and icteric and had signs of colic. Findings on CBC and serum biochemical analysis indicated marked systemic inflammation and hepatocellular damage. Serial abdominal ultrasonographic examinations revealed progressive, localized hepatic parenchymal abnormalities in the left ventral aspect of the abdomen in proximity to the left liver lobes, and eventual identification of an irregularly marginated, hyperechoic walled region of heterogenous echogenicity consistent with an encapsulated hepatic abscess.

TREATMENT AND OUTCOME

Medical treatment was initiated with administration of doxycycline and flunixin meglumine. After 7 days, the horse's clinical signs and hematologic values improved. After 14 days, the horse was discharged from the hospital and prescribed continuation of doxycycline treatment for 14 days. One week following hospital discharge, the horse was reevaluated for recurrent signs of colic and pyrexia. The horse was sedated, and the region overlying the caudal aspect of the seventh rib was desensitized with an inverted L nerve block by local infiltration with 2% lidocaine. While the horse was standing and sedated, drainage of an encapsulated intra-abdominal abscess was followed by rib resection and removal of a portion of necrotic left lateral liver lobe. The development of a pneumothorax following rib resection represented the only major surgical complication. Twelve months later, the horse was clinically normal and had returned to its previous level of performance.

CLINICAL RELEVANCE

Rib resection in standing sedated horses, together with appropriate medical management, should be considered an option for removal of well-encapsulated cranially located intra-abdominal abscesses that are adherent to the ventrolateral aspect of the body wall in horses.

Peritoneal reactivity evaluation in horses subjected to experimental small colon enterotomy and treated with subcutaneous heparin

Heparin is routinely administered in postoperative abdominal surgery aiming to prevent adhesions formation; however, there is no consensus indicating its effectiveness. This study evaluated the effect of heparin on peritoneal reactivity after abdominal surgery, through the association between peritoneal fluid features and ultrasonographic and laparoscopic examination. Ten adult horses were used: control group (CG) and treated group (TG). Both groups underwent laparotomy and small colon enterotomy. TG received subcutaneous heparin at 150 IU/kg every 12 hours for 5 days. The animals underwent ultrasonography and peritoneal fluid examination prior to enterotomy (M0) 12 hours (M1), 1 day (M2), 2 days (M3), 4 days (M4), 6 days (M5), 10 days (M6), and 14 days after enterotomy (M7) with laparoscopic examination being performed on the fifth postoperative day. Peritoneal inflammatory response was observed in both groups. The peritoneal fluid of TG animals showed higher echogenicity during heparin therapy. No inflammatory difference was observed between groups through peritoneal fluid features, except for the higher D-dimer concentration in CG. On laparoscopy, slightly diffuse peritoneal reactivity for both groups was observed, being higher for TG. Laparoscopy and ultrasonography association allowed detailed access to the abdominal cavity. Ultrasonography assessed the diffuse peritoneal inflammation, and laparoscopy allowed the detailed analysis of the segments. No gross beneficial reactions resulting from the use of heparin on peritoneal reactivity were observed; however, it was observed by D-dimer evaluation that the TG had less fibrin deposition, which is directly related to a lower rate of abdominal adhesions formation.

The importance of ultrasonographic pneumatosis intestinalis in equine neonatal gastrointestinal disease

REASONS FOR PERFORMING STUDY

Recognising the presence of a necrotising component of the gastrointestinal disease may be clinically useful in ill equine neonates.

OBJECTIVES

To study the importance of abdominal sonograms in neonatal foals suffering from gastrointestinal conditions and to describe the clinical features of necrotising gastrointestinal disease.

HYPOTHESIS

There is a subgroup of neonates with sonographically detectable pneumatosis intestinalis (PI), reflecting a necrotising disease.

METHODS

Records of foals aged < or = 7 days hospitalised from 2005 to 2009 with signs of gastrointestinal disease were evaluated (n = 89). The association of sonographic, clinical and clinicopathological signs with necrotising gastrointestinal disease and outcome was determined.

RESULTS

PI was imaged in 19 foals. Twenty-seven foals were classified as having necrotising gastrointestinal disease based on the presence of gastrointestinal signs (colic, diarrhoea, gastric reflux or abdominal distension) and sonographic PI (n = 19), surgical (n = 2) or pathological (n = 6) evidence of gastrointestinal necrosis. There was a difference between survival rate in foals with and without necrotising disease (33.3 and 69.4%, respectively, P = 0.005) or foals with and without PI detected sonographically (36.8 and 72.1%, respectively, P = 0.023). PI was the only sonographic finding associated with outcome. Prematurity, the presence of blood in the faeces, gastric reflux, abdominal distension, abnormal echogenicity of the colon and the lowest white blood cell count during hospitalisation were associated with necrotising gastrointestinal disease (P < 0.05).

CONCLUSIONS AND POTENTIAL RELEVANCE

Abdominal sonograms have prognostic value in neonatal gastrointestinal disease. PI and the presence of necrotising gastrointestinal disease were common and associated with a poor prognosis.