EQUINE VETERINARY EDUCATION / AE / JANUARY 2020


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intussusception (Bernard et al. 1989),ceco-colic intussusception (Taintor et al. 2004), pyloric-duodenal intussusception (Buchanan et al. 2006), large colon displacement (Grenager and Durham 2011; Ness et al. 2012), large colon volvulus (Abutarbush 2006), ascarid burden (Nielsen et al. 2016), pedunculated lipomas (Manso-Dıaz et al. 2018), and described in this issue, the visualisation of a small intestine adenomatous polyp causing intestinal obstruction (Younkin et al. 2020). Due to the depth of the adult equine abdomen there are obviously some limitations to the true completeness of the exam. Some of these specific findings are reliably assessed (such as large colon wall thickness and ability to visualise the left kidney). Encountering a specific finding such as an intussusception or the exact cause of a strangulation or luminal obstruction (i.e. lipoma or polyp), while exciting and can obviously support a decision for surgery (or euthanasia), in my experience, is usually rare. The ultimate question, of course, is whether or not an


ultrasound examination can truly help the clinician make a sound decision regarding the need for surgery. As an equine surgeon I can say yes, there have been times that my standard colic work-up is relatively unremarkable (e.g. occasional mild discomfort, no significant findings on rectal exam, no net reflux obtained, bloodwork within reference interval, no fluid yielded on abdominocentesis) and then an abnormal ultrasound examination (e.g. a single loop of thickened, partially distended, amotile small intestine) is what led me to recommend surgery for the patient, which had an early strangulating lesion that was correctable. A review of the literature finds studies that have attempted to answer this question scientifically. Beccati et al. (2011) performed a retrospective analysis of numerous colic cases that received ultrasound exams prior to surgery. They concluded that ultrasonography can help to distinguish between small and large intestinal lesions: finding small intestinal loops that are completely distended (round shape) and lacking motility is highly related to a definitive diagnosis of strangulating obstruction, while finding partially distended small intestinal loops (square shape) with reduced or normal contractility is


related to a large intestinal lesion. Increased peritoneal free fluid, reduced duodenal motility, and a completely distended appearance of the small intestinal loop with absent motility was significantly associated with a small intestinal strangulating lesion. Failure to visualise the left kidney was significantly associated with renosplenic entrapment of the large colon. A thickened appearance (>5 mm) and absent motility of the large intestine were found to be significantly associated with a strangulating volvulus of the large colon while absent motility of the large colon and failure to visualise small intestine was shown to be significantly associated with a non-strangulating volvulus of the large colon. Naylor (2015) and Cribb and Arroyo (2018) each reviewed the literature to report the accuracy of ultrasonography for predicting various gastrointestinal diseases by analysing statistics, including sensitivity, specificity, positive predictive values, and negative predictive values. Their findings were very similar to the retrospective analysis of Beccati et al. (2011). To conclude, I whole-heartedly believe that transabdominal


ultrasound has completely changed the colic work-up over the last few decades. It has made it more complete, allows for quicker recognition of small intestinal distention and wall thickening, can find a pocket of peritoneal fluid for successful


abdominocentesis, and can assess motility of small and large intestine. This information can help expedite the decision for surgical intervention for the benefit of the patient. There are still cases of surgical colic that I do not believe require an ultrasound examination, especially if the horse is so violently painful that it would be dangerous. I also believe that the ’routine field colic’ does not generally require an ultrasound examination, unless there are findings that need further evaluation, in which case it is no longer ‘routine’.In regards to finding a specific diagnosis via ultrasound, I think that it is very interesting and extremely helpful to find a surgical lesion pre-operatively, however other than leading to faster progression to euthanasia in horses without a surgical option, it will not likely change the clinical course in those that do. This does not mean that a clinician should not be on the lookout for such a finding, especially as the literature has continued to be expanded by them, however during the emergency ultrasound evaluation I think that the main focus should be on evaluating the horse for surgical need. If a definitive diagnosis can be quickly found it will help direct the clinical course but I do not think a prolonged amount of time should be spent trying to locate one of these specific findings if the horse has a surgical


option and the colic work-up and/or general ultrasound findings are directing towards that recommendation. I commend the authors of this accompanying case report (Younkin et al. 2020) for discovering a rare lesion ultrasonographically and reporting it for the benefitof expanding the literature.


Author’s declaration of interests No conflicts of interest have been declared.


Ethical animal research Not applicable.


Source of funding None.


References


Abutarbush, S.M. (2006) Use of ultrasonography to diagnose large colon volvulus in horses. J. Am. Vet. Med. Assoc. 228, 409-413.


Beccati, F., Pepe, M., Gialletti, R., Cercone, M., Bazzica, C. and Nannarone, S. (2011) Is there a statistical correlation between ultrasonographic findings and definitive diagnosis in horses with acute abdominal pain?. Equine Vet. J. 48, Suppl. 39, 98-105.


Bernard, W.V., Reef, V.B., Reimer, J.M., Humber, K.A. and Orsini, J.A. (1989) Ultrasonographic diagnosis of small-intestinal intussusception in three foals. J. Am. Vet. Med. Assoc. 194, 395-397.


Buchanan, B.R., Sommardahl, C.S., Moore, R.R. and Donnell, R.L. (2006) What is your diagnosis? Pyloric-duodenal intussusception. J. Am. Vet. Med. Assoc. 228, 1339-1340.


Busoni, V., De Busscher, V., Lopez, D., Verwilghen, D. and Cassart, D. (2006) Evaluation of a protocol for fast localised abdominal sonography of horses (FLASH) admitted for colic. Vet. J. 188, 77-82.


Byars, T.D. and Halley, J. (1986) Uses of ultrasound in equine internal medicine. Vet. Clin. North Am. Equine Pract. 2, 253-258.


Cribb, N.C. and Arroyo, L.G. (2018) Techniques and accuracy of abdominal ultrasound in gastrointestinal diseases of horses and foals. Vet. Clin. North Am. Equine Pract. 34, 25-38.


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