Incidence of superficial abdominal organ identification is similar using high-frequency linear (transrectal) and low-frequency curvilinear (abdominal) transducers in clinically healthy horses: A pilot study

Abdominal organ displacement is a potentially life-threatening condition in horses. Primary care veterinarians commonly make referral decisions based on a combination of clinical and ultrasonographic findings. However, published studies describing the effects of transducer on identifying abdominal organ locations in horses are currently lacking. The objective of this prospective, methods comparison, pilot study was to compare organ identification using a high-frequency linear (transrectal) transducer and a low-frequency curvilinear (abdominal) transducer for transcutaneous abdominal ultrasonography of healthy horses. Twelve clinically normal adult horses owned by the University of Calgary were enrolled in the study. Abdominal ultrasonography was performed by four practitioners, each randomly assigned to an alternating rotation of transrectal or abdominal transducer and left or right side of a horse. Using a Chi square test or Fisher's exact test, the frequency of identification for each organ was compared between both transducers. There was no significant difference in organ identification on the right side of the abdomen. On the left side, the stomach, liver, and kidney were less likely to be detected with the transrectal transducer. Compared with a low-frequency abdominal transducer, a high-frequency linear transrectal transducer delivers images that allow for organ identification in transcutaneous ultrasonography of the equine abdomen except for the left kidney, left liver, and stomach.