Received: 8 February 2024 | Accepted: 12 June 2024 DOI: 10.1111/eve.14025


R E V I EW A R T I C L E


Use of transrectal transducers in abdominal ultrasonography of horses: A review


Jean- Yin Tan 1 | Hanna Haardt 2


1 Faculty of Veterinary Medicine , University of Calgary , Calgary , Alberta , Canada 2 Department of Large Animal Surgery, Anaesthesia and Orthopaedics , Ghent University , Merelbeke , Belgium


Correspondence: Jean- Yin Tan Email: jeanyin.tan@ucalgary.ca


Funding information University of Calgary Faculty of Veterinary Medicine Internship Research Fund


Summary Abdominal ultrasonography is an important diagnostic tool in the evaluation of colic, yet primary care equine veterinary practitioners are often limited by availability and access to low- frequency (2–5 MHz curvilinear array or sector) abdominal transducers. Use of high- frequency (5–10 MHz linear array) transrectal transducers has not previously been compared with use of abdominal transducers for transcutaneous abdominal ultrasonog- raphy. One recent pilot study established that there was no significant difference in organ detection by the two transducers on the right side of the equine abdomen, but the stom- ach, liver and kidney on the left side were less likely to be detected using the transrectal transducer in healthy horses. A clinical study found that the transrectal transducer can be used successfully using the FLASH protocol in horses presenting with colic, with high- quality images that detected abnormalities of the peritoneal fluid, small intestine and large intestine. The transrectal transducer had decreased visualisation of the stomach and left kidney and was less likely to detect pathology surrounding these organs. This is the first series of studies to evaluate use of transrectal transducers in abdominal ultra- sonography of the horse, a tool that is readily accessible to the field practitioner.


K E YWORDS horse , colic , diagnostic imaging , probe , ultrasound


BACKGROUND


Colic is a common condition in horse, with an incidence of 4.2 events/100 horses per year. It is a leading cause of death among horses, second only to old age (USDA, 2001 ). Abdominal ultraso- nography is an important diagnostic tool during colic evaluation and identifies small intestinal obstruction, determines intestinal motility and has a role in the accurate definitive diagnosis of lesions of the small and large intestine (Beccati et al., 2011 ; Scharner et al., 2015 ). The equine abdomen is traditionally scanned using a 2–5 MHz


curvilinear array or sector transducer, colloquially known as the ‘ab- dominal probe’ (and referred hereinafter as ‘abdominal transducer’) yet few primary care equine veterinary practitioners have access to this transducer. While this may vary based on geographic location,


only 8% of ultrasound machines purchased for use in equine prac- tice in Canada from 2016 to 2021 included an abdominal transducer (Walklate, 2021 ). In addition, the use of a wireless 3.5 MHz curvi- linear probe for the examination of colic cases in the field has re- cently been described (Corrie et al., 2024 ). Meanwhile, practitioners commonly use 5–10 MHz linear array ultrasound transducers for reproductive examinations (colloquially known as the ‘rectal probe’ and referred hereinafter as ‘transrectal


transducer’). Given that


colic accounts for 1/3 of afterhours calls in primary care and only 1/5 of these cases may be hospitalised, of which 81% subsequently undergo abdominal ultrasound, field ultrasonography may assist with rapid decision- making in the field (Bowden et al., 2020 ; Burrell (nee Lightfoot) et al., 2023 ; Proudman et al., 2002 ; Scantlebury et al., 2014 ).


This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2024 The Author(s). Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd.


Equine Vet Educ. 2024;36:603–606. aaep.org/wiley-redirect | 603

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